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2008-08-24 by Mu
Hullo again, I recently received an MS-10 in poor condition - it has been cannibalized, and is missing - 10 K (A and B), 100 K (A and B) and 2M pots - several keys - knobs, both large and small - A replacement powersupply could be in order, too. I hate to see a classic machine in such a state, and will put it back in shape - as quickly and original as budget allows. Any and all hints appreciated - yours, Mu.
2008-08-24 by Philip
I just got a broken Memorymoog. It's really clean, near mint in fact, but not working. Half the reason I bought it is because I like a challenge :o) ..I haven't even opened it up yet so I thought I'd post up the problems to see if anyone has an idea. It boots up ok, but makes very little sound the most you get out of it is a thump or slight squeak when you hit a key, the same pitch wherever you hit. The digital side seem to be mostly working. If you hit autotune it comes back with '0 tuned' so it can't tune any of the oscillators probably because it cant 'hear' them so to speak. First thoughts are some kind of DAC problem. 2: All the LED's on the left hand side don't work at all but the buttons do. A few are just stuck on all the time, again the buttons work. 3: one digit on the alpha/numeric display is barely visible. 4: this is a slightly weird one which is hard to describe, when you move the pots the numbers in the alpha display move up and down which is correct., however say you turn one pot and move to another, well the first pots status doesn't clear from the display, it's stuck there, you can see it flicker as you move the other pot but it's stuck there unless you go back and zero the original pot. Only a few pots seem to cause this problem. Any ideas would be helpful. Obviously the first thing im going to check is the PSU when I open it up later. Thanks, Phil. Send instant messages to your online friends http://uk.messenger.yahoo.com
2008-08-25 by eggwheatis
Well ive now got sound out of it :o) this is going to be fun though...yet again someones been in this before me that looks like they weren't on the ball. All the IC are in sockets...but most of them have been replaced sometimes with the wrong variant. No sound was indeed caused by the PSU....an electrolytic capacitor in the +15 circuit on the DMUX board was put in backwards. Repairer error #1. I thought I'd start by fixing the LED's on the left hand control(LHC) board and the missing digit in the alpha display so I could see what was going on better... The dead/stuck on LED's were caused by one of the legs of the ls378 at U8 on the LHC board being bent under itself in the socket. Repairer error #2. The dead digit in the alpha display was caused by a dead output on the LS273 at U1 on the LHC board. Anyway so now I can see and hear whats going on I have a whole host of new problems :o) I have no Oscillator 3 at all across the board, Osc 1 and 2 also dont work on one voice. None of the oscillators will auto-tune, i get the '0 tuned message'. The filter self oscillates but wont track the keyboard. The switch matrix is hopeless on the LHC board, buttons activate wrong functions basically, the appegiator doesnt work nor does the hold function... Things I can see right off the bat but need to get spares to fix are: All the 74ls138's on the digital board have been replaced with HC Cmos variants...not a good idea, these are not compatible with TTL in most cases, so i would think they are causing a lot of problems (fingers crossed). You need LS in there or HCT at least.. Repairer Error #3 Also there is a TL071 missing out of a socket on the DMUX board..this is connected to the auto tune circuit..buffers one of the outputs I think. Repairer Error #4 All in all a lot of fun! Phil. --- In vintagesynthrepair@yahoogroups.com, Philip <eggwheatis@...> wrote: > > I just got a broken Memorymoog. It's really clean, near mint in fact, but not working. Half the reason I bought it is because I like a challenge :o) ..I haven't even opened it up yet so I thought I'd post up the problems to see if anyone has an idea. >  > It boots up ok, but makes very little sound the most you get out of it is a thump or slight squeak when you hit a key, the same pitch wherever you hit. The digital side seem to be mostly working. >  > If you hit autotune it comes back with '0 tuned' so it can't tune any of the oscillators probably because it cant 'hear' them so to speak. >  > First thoughts are some kind of DAC problem. >  > 2: All the LED's on the left hand side don't work at all but the buttons do. A few are just stuck on all the time, again the buttons work. >  > 3: one digit on the alpha/numeric display is barely visible. >  > 4: this is a slightly weird one which is hard to describe, when you move the pots the numbers in the alpha display move up and down which is correct., however say you turn one pot and move to another, well the first pots status doesn't clear from the display, it's stuck there, you can see it flicker as you move the other pot but it's stuck there unless you go back and zero the original pot. Only a few pots seem to cause this problem. >  > Any ideas would be helpful. Obviously the first thing im going to check is the PSU when I open it up later. >  > Thanks, Phil. >  > > Send instant messages to your online friends http://uk.messenger.yahoo.com >
2008-08-26 by eggwheatis
Fixed the hopeless switch matrix :o) there was a ribbon cable plugged in the wrong way round into the common analogue board! Large repairer error #5..... So now all the button functions work properly and I have Oscillator 3 back!... although only 4 voices working. I also changed 4 of the hc138's to LS138's and the filter has now started tracking the keyboard properly...I discovered two HC377's on the digital board too..they should be LS variants again... So basically im left with OSC 1,2 and 3 not working on the same voice card(3 dead cem3340's on the same card surely not? I hope) OSC 3 dead on one other card. Hopeless autotune '0 tuned' all out of tune with each other even on the same cards... Oh and the weird pot problem: when you move the pots the numbers in the alpha display move up and down which is correct, however say you turn one pot and move to another, well the first pots status doesn't clear from the display, it's stuck there, you can see it flicker as you move the other pot but it's stuck there unless you go back and zero the original pot. Only a few pots seem to cause this problem. I reckon swapping out those wrong HC ic's will cure that..maybe.. Im sure I'll find more problems too. It's amazing how 'previous repairer error' can completely disable a synth that probably only had a couple of faults to start with. Getting there... --- In vintagesynthrepair@yahoogroups.com, "eggwheatis" <eggwheatis@...> wrote: > > Well ive now got sound out of it :o) this is going to be fun > though...yet again someones been in this before me that looks like > they weren't on the ball. All the IC are in sockets...but most of > them have been replaced sometimes with the wrong variant. > > No sound was indeed caused by the PSU....an electrolytic capacitor in > the +15 circuit on the DMUX board was put in backwards. Repairer > error #1. > > I thought I'd start by fixing the LED's on the left hand control (LHC) > board and the missing digit in the alpha display so I could see what > was going on better... > > The dead/stuck on LED's were caused by one of the legs of the ls378 > at U8 on the LHC board being bent under itself in the socket. > Repairer error #2. > > The dead digit in the alpha display was caused by a dead output on > the LS273 at U1 on the LHC board. > > Anyway so now I can see and hear whats going on I have a whole host > of new problems :o) > > I have no Oscillator 3 at all across the board, Osc 1 and 2 also dont > work on one voice. None of the oscillators will auto-tune, i get > the '0 tuned message'. The filter self oscillates but wont track the > keyboard. > > The switch matrix is hopeless on the LHC board, buttons activate > wrong functions basically, the appegiator doesnt work nor does the > hold function... > > Things I can see right off the bat but need to get spares to fix are: > All the 74ls138's on the digital board have been replaced with HC > Cmos variants...not a good idea, these are not compatible with TTL in > most cases, so i would think they are causing a lot of problems > (fingers crossed). You need LS in there or HCT at least.. Repairer > Error #3 > > Also there is a TL071 missing out of a socket on the DMUX board..this > is connected to the auto tune circuit..buffers one of the outputs I > think. Repairer Error #4 > > All in all a lot of fun! > > Phil. > > > > > --- In vintagesynthrepair@yahoogroups.com, Philip <eggwheatis@> > wrote: > > > > I just got a broken Memorymoog. It's really clean, near mint in > fact, but not working. Half the reason I bought it is because I like > a challenge :o) ..I haven't even opened it up yet so I thought I'd > post up the problems to see if anyone has an idea. > >  > > It boots up ok, but makes very little sound the most you get out of > it is a thump or slight squeak when you hit a key, the same pitch > wherever you hit. The digital side seem to be mostly working. > >  > > If you hit autotune it comes back with '0 tuned' so it can't tune > any of the oscillators probably because it cant 'hear' them so to > speak. > >  > > First thoughts are some kind of DAC problem. > >  > > 2: All the LED's on the left hand side don't work at all but the > buttons do. A few are just stuck on all the time, again the buttons > work. > >  > > 3: one digit on the alpha/numeric display is barely visible. > >  > > 4: this is a slightly weird one which is hard to describe, when you > move the pots the numbers in the alpha display move up and down which > is correct., however say you turn one pot and move to another, > well the first pots status doesn't clear from the display, it's > stuck there, you can see it flicker as you move the other pot but > it's stuck there unless you go back and zero the original pot. Only
> a few pots seem to cause this problem. > >  > > Any ideas would be helpful. Obviously the first thing im going to > check is the PSU when I open it up later. > >  > > Thanks, Phil. > >  > > > > Send instant messages to your online friends > http://uk.messenger.yahoo.com > > >
2008-08-27 by duncan
phil- following your journey with interest & some sympathy. I have fallen foul of "someone's been in here before me" syndrome too, although (thank bob) not in the case of my memorymoog, which is a LAMM in any case. you could do a lot worse than take y'rself over to the rather quiet mini/memorymoog list & cross-post there. also, I believe rudi linhard (mr LAMM) has a colleague in the US who may be able/willing to offer some pointers. if you can afford it & are willing to step away from the project yourself, the LAMM upgrade is the best gift you can give to this mighty synth. presumably you have the schemos? one last thing- get some caig on the connectors, & check that they all seat properly. I had a "5-tuned" scenario a year or so ago, where osc-3 on one voice wouldn't track. that was a loose connector. good luck! duncan/r.m.i./LAMM#1290
2008-08-27 by Philip
Thanks a lot! I could no way afford the LAMM upgrade..It's so expensive, plus the risk and expense of shipping. Also there are a couple of reasons I think I dont need it even if I did have the cash and were willing to take the risk. First off my friend has owned a memorymoog for 15 years without a single problem I have spoke to other owners and they have said similar or have had minimal problems. I believe as long as you maintain them and dont move them around too much they are fine. I never trust what I read on the net Im sure these things get hyped up out of all preportion. I can obviously see how this thing would be prone to failure though with all those molex connectors, ribbons, curtis chips, heat etc. Secondly I dont need MIDI, a big part of the LAMM upgrade is the excellent MIDI upgrade. I personally hate MIDI and never use it. My experience is that a Memorymoog plus is also worse than a non-plus, LAMM themselves rip it out and throw the upgrade away. Having the sequencer and MIDI does nothing but put more strain on that poor Z80. Not that the net would have you believe that. If you dont need the MIDI option, there is so much you can do yourself to vastly improve this machine., upgrade the PSU, upgrade the OS, perform the Autotune upgrade, perform all the mods MOOG themselves put out in bulletins and much more. I will get it fixed first, then perform all the upgrades I can think of or find. I'll live with it for a while and see what happens...see how often it breaks down! I have fixed a lot more...I'll post it up later :o) Thanks, Phil. --- On Wed, 27/8/08, duncan <ferrograph@...> wrote:
From: duncan <ferrograph@...> Subject: [vintagesynthrepair] Re: Memorymoog repair To: vintagesynthrepair@yahoogroups.com Date: Wednesday, 27 August, 2008, 12:47 PM phil- following your journey with interest & some sympathy. I have fallen foul of "someone's been in here before me" syndrome too, although (thank bob) not in the case of my memorymoog, which is a LAMM in any case. you could do a lot worse than take y'rself over to the rather quiet mini/memorymoog list & cross-post there. also, I believe rudi linhard (mr LAMM) has a colleague in the US who may be able/willing to offer some pointers. if you can afford it & are willing to step away from the project yourself, the LAMM upgrade is the best gift you can give to this mighty synth. presumably you have the schemos? one last thing- get some caig on the connectors, & check that they all seat properly. I had a "5-tuned" scenario a year or so ago, where osc-3 on one voice wouldn't track. that was a loose connector. good luck! duncan/r.m.i. /LAMM#1290 Send instant messages to your online friends http://uk.messenger.yahoo.com
2008-08-27 by eggwheatis
A bit more fixed..:o) well actually diagnosed.. The reason all the voices were dead on one card was because a CEM3340 VCO chip was shorted, this pulled down the 7905 regulator that sits on the edge of each voice card killing the supply to the other CEM's. I found that a CEM3360 VCA chip was also dead on the same card. So after swapping a few CEM's around I know have just one Oscillator 3 down. After that I noticed the VCF adsr wasnt working on one voice. A quick look at the schems revealed it is generated by a CEM3310 on the contour generator board. Sure enough I found the 3310 was dead. So that, on the face of it, appears to be the voices sorted out. Im sure I'll find more problems. The synth is still totally out of tune, so it will need full calibration. I'm not going to try that until I have located all the CEM chips I need. I also swapped all the HC ic's out for the correct LS versions and anything that isnt specified in the parts list. For instance a lot of the op amps are 1458's, the schematics and parts list specify 4558. The manual also has an addition saying you should swap any found to 4558. The 4558 is apparently superior. I still have the problem with the displayed pot values, I talked about in an earlier post(below). It drove me mad..I checked out the whole of the POTPOS circuit, the MUX circuit..the display circuits....eventually after forgetting theory, schematics and just randomly testing things, I found CR1 to be open on the DMUX board! It's a 6.2 Zener..I avent changed it yet as I was going out..but after checking the schems I reckon I might have solved it..it's not mentioned in the service manual, and it's right on the edge of the schems.. Thats it for now..Phil. --- In vintagesynthrepair@yahoogroups.com, "eggwheatis" <eggwheatis@...> wrote: > > Fixed the hopeless switch matrix :o) there was a ribbon cable plugged > in the wrong way round into the common analogue board! Large repairer > error #5..... > > So now all the button functions work properly and I have Oscillator 3 > back!... although only 4 voices working. > > I also changed 4 of the hc138's to LS138's and the filter has now > started tracking the keyboard properly...I discovered two HC377's on > the digital board too..they should be LS variants again... > > So basically im left with OSC 1,2 and 3 not working on the same voice > card(3 dead cem3340's on the same card surely not? I hope) OSC 3 dead > on one other card. Hopeless autotune '0 tuned' all out of tune with > each other even on the same cards... > > Oh and the weird pot problem: when you > move the pots the numbers in the alpha display move up and down which > is correct, however say you turn one pot and move to another, > well the first pots status doesn't clear from the display, it's > stuck there, you can see it flicker as you move the other pot but > it's stuck there unless you go back and zero the original pot. Only > a few pots seem to cause this problem. > > I reckon swapping out those wrong HC ic's will cure that..maybe.. > > Im sure I'll find more problems too. It's amazing how 'previous > repairer error' can completely disable a synth that probably only had > a couple of faults to start with. > > Getting there... > > > > --- In vintagesynthrepair@yahoogroups.com, "eggwheatis" > <eggwheatis@> wrote: > > > > Well ive now got sound out of it :o) this is going to be fun > > though...yet again someones been in this before me that looks like > > they weren't on the ball. All the IC are in sockets...but most of > > them have been replaced sometimes with the wrong variant. > > > > No sound was indeed caused by the PSU....an electrolytic capacitor > in > > the +15 circuit on the DMUX board was put in backwards. Repairer > > error #1. > > > > I thought I'd start by fixing the LED's on the left hand control > (LHC) > > board and the missing digit in the alpha display so I could see > what > > was going on better... > > > > The dead/stuck on LED's were caused by one of the legs of the ls378 > > at U8 on the LHC board being bent under itself in the socket. > > Repairer error #2. > > > > The dead digit in the alpha display was caused by a dead output on > > the LS273 at U1 on the LHC board. > > > > Anyway so now I can see and hear whats going on I have a whole host > > of new problems :o) > > > > I have no Oscillator 3 at all across the board, Osc 1 and 2 also > dont > > work on one voice. None of the oscillators will auto-tune, i get > > the '0 tuned message'. The filter self oscillates but wont track > the > > keyboard. > > > > The switch matrix is hopeless on the LHC board, buttons activate > > wrong functions basically, the appegiator doesnt work nor does the > > hold function... > > > > Things I can see right off the bat but need to get spares to fix > are: > > All the 74ls138's on the digital board have been replaced with HC > > Cmos variants...not a good idea, these are not compatible with TTL > in > > most cases, so i would think they are causing a lot of problems > > (fingers crossed). You need LS in there or HCT at least.. Repairer > > Error #3 > > > > Also there is a TL071 missing out of a socket on the DMUX > board..this > > is connected to the auto tune circuit..buffers one of the outputs I > > think. Repairer Error #4 > > > > All in all a lot of fun! > > > > Phil. > > > > > > > > > > --- In vintagesynthrepair@yahoogroups.com, Philip <eggwheatis@> > > wrote: > > > > > > I just got a broken Memorymoog. It's really clean, near mint in > > fact, but not working. Half the reason I bought it is because I > like > > a challenge :o) ..I haven't even opened it up yet so I thought I'd > > post up the problems to see if anyone has an idea. > > >  > > > It boots up ok, but makes very little sound the most you get out > of > > it is a thump or slight squeak when you hit a key, the same pitch > > wherever you hit. The digital side seem to be mostly working. > > >  > > > If you hit autotune it comes back with '0 tuned' so it can't tune > > any of the oscillators probably because it cant 'hear' them so to > > speak. > > >  > > > First thoughts are some kind of DAC problem. > > >  > > > 2: All the LED's on the left hand side don't work at all but the > > buttons do. A few are just stuck on all the time, again the buttons > > work. > > >  > > > 3: one digit on the alpha/numeric display is barely visible. > > >  > > > 4: this is a slightly weird one which is hard to describe, when > you > > move the pots the numbers in the alpha display move up and down > which > > is correct., however say you turn one pot and move to another, > > well the first pots status doesn't clear from the display, it's > > stuck there, you can see it flicker as you move the other pot but > > it's stuck there unless you go back and zero the original pot. > Only > > a few pots seem to cause this problem. > > >  > > > Any ideas would be helpful. Obviously the first thing im going to
> > check is the PSU when I open it up later. > > > Â > > > Thanks, Phil. > > > Â > > > > > > Send instant messages to your online friends > > http://uk.messenger.yahoo.com > > > > > >
2008-08-28 by eggwheatis
Well this (hopefully)last problem is proving to be really difficult to solve. It wasnt the Zener even though it was bad. It acts as a regulator for the +10 vdc to the DAC from the Control boards... It was causing it to sit at 11.5 vdc. Changing it did nothing. It's one of those niggling annoying problems that seems to be undetectable...its driving me nuts..I'll try to explain it better. Basically you turn a pot on this synth and the pots value is shown on the alpha/dec LED display, you turn the second pot the display instantly shows that pots value..so far so good...but after a few turns of various pots, it will stick on a value and won't change with the new pot movements, pressing buttons, turning other pots wont get rid of it(you can see the correct values flickering behind it)..even turning it on and off. You have to go back and find the pot thats got the value 'stuck'. Zero that pot and it's fine again. It's totally random and depends on the combination of pots and values. The actual sound itself changes fine with the pot movement. It's just the displaying of the values that is a bit screwed. Remember is the physical displaying of the values that gets stuck, not the actual values that control the analogue parameters. They are working fine. If anyone can help I'd really appreciate it, the schems are here: http://www.matrixsynth.com/blog/media/Moog/MemorymoogSchematics/ The service manual is here: http://www.retrosynth.com/docs/memorymoog/mm_service.pdf Apart from this fault..it seems to be almost fixed. Thanks, Phil. --- In vintagesynthrepair@yahoogroups.com, "eggwheatis" <eggwheatis@...> wrote: > > A bit more fixed..:o) > > well actually diagnosed.. > > The reason all the voices were dead on one card was because a > CEM3340 VCO chip was shorted, this pulled down the 7905 regulator > that sits on the edge of each voice card killing the supply to the > other CEM's. I found that a CEM3360 VCA chip was also dead on the > same card. So after swapping a few CEM's around I know have just one > Oscillator 3 down. > > After that I noticed the VCF adsr wasnt working on one voice. A > quick look at the schems revealed it is generated by a CEM3310 on > the contour generator board. Sure enough I found the 3310 was dead. > > So that, on the face of it, appears to be the voices sorted out. Im > sure I'll find more problems. > > The synth is still totally out of tune, so it will need full > calibration. I'm not going to try that until I have located all the > CEM chips I need. > > I also swapped all the HC ic's out for the correct LS versions and > anything that isnt specified in the parts list. For instance a lot > of the op amps are 1458's, the schematics and parts list specify > 4558. The manual also has an addition saying you should swap any > found to 4558. The 4558 is apparently superior. > > I still have the problem with the displayed pot values, I talked > about in an earlier post(below). It drove me mad..I checked out the > whole of the POTPOS circuit, the MUX circuit..the display > circuits....eventually after forgetting theory, schematics and just > randomly testing things, I found CR1 to be open on the DMUX board! > It's a 6.2 Zener..I avent changed it yet as I was going out..but > after checking the schems I reckon I might have solved it..it's not > mentioned in the service manual, and it's right on the edge of the > schems.. > > Thats it for now..Phil. > > > > > > > > > --- In vintagesynthrepair@yahoogroups.com, "eggwheatis" > <eggwheatis@> wrote: > > > > Fixed the hopeless switch matrix :o) there was a ribbon cable > plugged > > in the wrong way round into the common analogue board! Large > repairer > > error #5..... > > > > So now all the button functions work properly and I have > Oscillator 3 > > back!... although only 4 voices working. > > > > I also changed 4 of the hc138's to LS138's and the filter has now > > started tracking the keyboard properly...I discovered two HC377's > on > > the digital board too..they should be LS variants again... > > > > So basically im left with OSC 1,2 and 3 not working on the same > voice > > card(3 dead cem3340's on the same card surely not? I hope) OSC 3 > dead > > on one other card. Hopeless autotune '0 tuned' all out of tune > with > > each other even on the same cards... > > > > Oh and the weird pot problem: when you > > move the pots the numbers in the alpha display move up and down > which > > is correct, however say you turn one pot and move to another, > > well the first pots status doesn't clear from the display, it's > > stuck there, you can see it flicker as you move the other pot but > > it's stuck there unless you go back and zero the original pot. > Only > > a few pots seem to cause this problem. > > > > I reckon swapping out those wrong HC ic's will cure that..maybe.. > > > > Im sure I'll find more problems too. It's amazing how 'previous > > repairer error' can completely disable a synth that probably only > had > > a couple of faults to start with. > > > > Getting there... > > > > > > > > --- In vintagesynthrepair@yahoogroups.com, "eggwheatis" > > <eggwheatis@> wrote: > > > > > > Well ive now got sound out of it :o) this is going to be fun > > > though...yet again someones been in this before me that looks > like > > > they weren't on the ball. All the IC are in sockets...but most > of > > > them have been replaced sometimes with the wrong variant. > > > > > > No sound was indeed caused by the PSU....an electrolytic > capacitor > > in > > > the +15 circuit on the DMUX board was put in backwards. Repairer > > > error #1. > > > > > > I thought I'd start by fixing the LED's on the left hand control > > (LHC) > > > board and the missing digit in the alpha display so I could see > > what > > > was going on better... > > > > > > The dead/stuck on LED's were caused by one of the legs of the > ls378 > > > at U8 on the LHC board being bent under itself in the socket. > > > Repairer error #2. > > > > > > The dead digit in the alpha display was caused by a dead output > on > > > the LS273 at U1 on the LHC board. > > > > > > Anyway so now I can see and hear whats going on I have a whole > host > > > of new problems :o) > > > > > > I have no Oscillator 3 at all across the board, Osc 1 and 2 also > > dont > > > work on one voice. None of the oscillators will auto-tune, i get > > > the '0 tuned message'. The filter self oscillates but wont track > > the > > > keyboard. > > > > > > The switch matrix is hopeless on the LHC board, buttons activate > > > wrong functions basically, the appegiator doesnt work nor does > the > > > hold function... > > > > > > Things I can see right off the bat but need to get spares to fix > > are: > > > All the 74ls138's on the digital board have been replaced with > HC > > > Cmos variants...not a good idea, these are not compatible with > TTL > > in > > > most cases, so i would think they are causing a lot of problems > > > (fingers crossed). You need LS in there or HCT at least.. > Repairer > > > Error #3 > > > > > > Also there is a TL071 missing out of a socket on the DMUX > > board..this > > > is connected to the auto tune circuit..buffers one of the > outputs I > > > think. Repairer Error #4 > > > > > > All in all a lot of fun! > > > > > > Phil. > > > > > > > > > > > > > > > --- In vintagesynthrepair@yahoogroups.com, Philip <eggwheatis@> > > > wrote: > > > > > > > > I just got a broken Memorymoog. It's really clean, near mint > in > > > fact, but not working. Half the reason I bought it is because I > > like > > > a challenge :o) ..I haven't even opened it up yet so I thought > I'd > > > post up the problems to see if anyone has an idea. > > > >  > > > > It boots up ok, but makes very little sound the most you get > out > > of > > > it is a thump or slight squeak when you hit a key, the same > pitch > > > wherever you hit. The digital side seem to be mostly working. > > > >  > > > > If you hit autotune it comes back with '0 tuned' so it can't > tune > > > any of the oscillators probably because it cant 'hear' them so > to > > > speak. > > > >  > > > > First thoughts are some kind of DAC problem. > > > >  > > > > 2: All the LED's on the left hand side don't work at all but > the > > > buttons do. A few are just stuck on all the time, again the > buttons > > > work. > > > >  > > > > 3: one digit on the alpha/numeric display is barely visible. > > > >  > > > > 4: this is a slightly weird one which is hard to describe, > when > > you > > > move the pots the numbers in the alpha display move up and down > > which > > > is correct., however say you turn one pot and move to another, > > > well the first pots status doesn't clear from the display, it's > > > stuck there, you can see it flicker as you move the other pot > but > > > it's stuck there unless you go back and zero the original pot. > > Only > > > a few pots seem to cause this problem. > > > >  > > > > Any ideas would be helpful. Obviously the first thing im going
> to > > > check is the PSU when I open it up later. > > > > Â > > > > Thanks, Phil. > > > > Â > > > > > > > > Send instant messages to your online friends > > > http://uk.messenger.yahoo.com > > > > > > > > > >
2008-08-28 by scott frye
If the same pot is the one that's sticking ( locking up the values) Spray the heck out of it with some de-oxit. If that doesnt work, find out which A / D lines and IC connect to THAT pot. Is the CLK strobing that chip properly? If it's sampled back at the micro is the clock OK for the micro? Just some thoughts w/o looking at the schema. Problems like that also occur on the SIEL DK600 and Opera. Scott Frye AudioFixation Consumer / Pro Audio Repair Southern VT "Resistance is futile but..... Impedance is much more complex"
2008-08-29 by Philip
Hi Scott, I'll look at that...but it doesnt seem to be caused by a single pot...I have just sprayed every single pot...no difference. Another symptom: It shows the stored pot value on the left and the actual value on the right. One pots stored value was 31...well i started turning another pot whose stored value was 49 and as I turned it slowly the stored value would flicker back to 31..if i turned it slowly i could make it step between 31 and 49. It's like data lines are bleeding into one another. Or like a certain mix of positions of pots confuse it.... It's hurting my head this one... --- On Fri, 29/8/08, scott frye <painintheamp@...> wrote:
From: scott frye <painintheamp@...> Subject: [vintagesynthrepair] Re: Memorymoog repair To: vintagesynthrepair@yahoogroups.com Date: Friday, 29 August, 2008, 12:29 AM If the same pot is the one that's sticking ( locking up the values) Spray the heck out of it with some de-oxit. If that doesnt work, find out which A / D lines and IC connect to THAT pot. Is the CLK strobing that chip properly? If it's sampled back at the micro is the clock OK for the micro? Just some thoughts w/o looking at the schema. Problems like that also occur on the SIEL DK600 and Opera. Scott Frye AudioFixation Consumer / Pro Audio Repair Southern VT "Resistance is futile but..... Impedance is much more complex" Send instant messages to your online friends http://uk.messenger.yahoo.com
2008-08-29 by paintingwithsound
If one pot is doing it then check that pot and track leading to it. If three are doing it then look for a dud 4051 or similar (haven't seen the schematics - copy anyone?), if all pots are doing it then the a/d is faulty. --- In vintagesynthrepair@yahoogroups.com, Philip <eggwheatis@...> wrote: > > Hi Scott, I'll look at that...but it doesnt seem to be caused by a single pot...I have just sprayed every single pot...no difference. >  > Another symptom: It shows the stored pot value on the left and the actual value on the right. One pots stored value was 31...well i started turning another pot whose stored value was 49 and as I turned it slowly the stored value would flicker back to 31..if i turned it slowly i could make it step between 31 and 49. It's like data lines are bleeding into one another. Or like a certain mix of positions of pots confuse it.... >  > It's hurting my head this one... > > --- On Fri, 29/8/08, scott frye <painintheamp@...> wrote: > > From: scott frye <painintheamp@...> > Subject: [vintagesynthrepair] Re: Memorymoog repair > To: vintagesynthrepair@yahoogroups.com > Date: Friday, 29 August, 2008, 12:29 AM > > > > > > > > > > > If the same pot is the one that's sticking ( locking up the values) Spray the heck out of it with some de-oxit. > If that doesnt work, find out which A / D lines and IC connect to THAT pot. > Is the CLK strobing that chip properly? If it's sampled back at the micro is the clock OK for the micro? > Just some thoughts w/o looking at the schema. > > Problems like that also occur on the SIEL DK600 and Opera. > > > > > Scott Frye > AudioFixation > Consumer / Pro Audio Repair > Southern VT > > "Resistance is futile but..... > Impedance is much more complex" > > > > > > > > > > > > > > > > > Send instant messages to your online friends http://uk.messenger.yahoo.com >
2008-08-29 by Philip
http://www.matrixsynth.com/blog/media/Moog/MemorymoogSchematics/ all the 4051's have been swapped out by someone before me...in fact nearly every IC except for the expensive IC's have been swapped out in this synth. Everything is sockets...so it's easy to do. Like I say it doesnt appear to be one pot... --- On Fri, 29/8/08, paintingwithsound <cfmh@xtra.co.nz> wrote:
From: paintingwithsound <cfmh@...> Subject: [vintagesynthrepair] Re: Memorymoog repair To: vintagesynthrepair@yahoogroups.com Date: Friday, 29 August, 2008, 3:47 AM If one pot is doing it then check that pot and track leading to it. If three are doing it then look for a dud 4051 or similar (haven't seen the schematics - copy anyone?), if all pots are doing it then the a/d is faulty. --- In vintagesynthrepair@ yahoogroups. com, Philip <eggwheatis@ ...> wrote: > > Hi Scott, I'll look at that...but it doesnt seem to be caused by a single pot...I have just sprayed every single pot...no difference. >  > Another symptom: It shows the stored pot value on the left and the actual value on the right. One pots stored value was 31...well i started turning another pot whose stored value was 49 and as I turned it slowly the stored value would flicker back to 31..if i turned it slowly i could make it step between 31 and 49. It's like data lines are bleeding into one another. Or like a certain mix of positions of pots confuse it.... >  > It's hurting my head this one... > > --- On Fri, 29/8/08, scott frye <painintheamp@ ...> wrote: > > From: scott frye <painintheamp@ ...> > Subject: [vintagesynthrepair ] Re: Memorymoog repair > To: vintagesynthrepair@ yahoogroups. com > Date: Friday, 29 August, 2008, 12:29 AM > > > > > > > > > > > If the same pot is the one that's sticking ( locking up the values) Spray the heck out of it with some de-oxit. > If that doesnt work, find out which A / D lines and IC connect to THAT pot. > Is the CLK strobing that chip properly? If it's sampled back at the micro is the clock OK for the micro? > Just some thoughts w/o looking at the schema. > > Problems like that also occur on the SIEL DK600 and Opera. > > > > > Scott Frye > AudioFixation > Consumer / Pro Audio Repair > Southern VT > > "Resistance is futile but..... > Impedance is much more complex" > > > > > > > > > > > > > > > > > Send instant messages to your online friends http://uk.messenger .yahoo.com > Send instant messages to your online friends http://uk.messenger.yahoo.com
2008-09-03 by eggwheatis
Phew..I fixed the pot problem, well I think I have. I ended up taking every board out and going through them with a fine toothed comb, I cleaned any surplus flux off, checked everything..scoped everything. I just could not find it. Then something occured to me..like many things do when repairing stuff!..on the schematics there is an LF351 op-amp on the output of the DAC..but it the actual socket was a TL071 which should be fine, and i had already swapped it out..anyway it is an equivalent and is even mentioned in parenthesis on the parts sheet next to LF351, as is TL072 as an equivalent for LF353. In fact my memorymoog has TL072'a and TL)71's throughout. Now I know how sensitive digital circuits are to 'equivalents' so I put in an LF351 and bingo....it was fixed! Or so I thought basically I did it again once after playing around with it after an hour..now normally it did it every 30 seconds so it is 99% better and hasn't done it again. Maybe the DAC is faulty itself but I still don't understand how this would effect the displayed pot values. Surely that's down to the A/D? Also with good news comes bad...after fixing that problem I rechecked the voices..I had lost another voice! AFter finding another red hot regulator on a voice board I found all three CEM3340's were shorted!! Arggh!! I was feeling pretty sick considering how expensive they are! I must have shorted something out while trying to fix the pot problem...oh well.. So anyway I've got 5 CEM3340's on the way(one spare), a 3310 and a 3360. After calibration that should be it. Fingers crossed X --- In vintagesynthrepair@yahoogroups.com, "eggwheatis" <eggwheatis@...> wrote: > > Well this (hopefully)last problem is proving to be really difficult > to solve. It wasnt the Zener even though it was bad. It acts as a > regulator for the +10 vdc to the DAC from the Control boards... It > was causing it to sit at 11.5 vdc. Changing it did nothing. > > It's one of those niggling annoying problems that seems to be > undetectable...its driving me nuts..I'll try to explain it better. > > Basically you turn a pot on this synth and the pots value is shown on > the alpha/dec LED display, you turn the second pot the display > instantly shows that pots value..so far so good...but after a few > turns of various pots, it will stick on a value and won't change with > the new pot movements, pressing buttons, turning other pots wont get > rid of it(you can see the correct values flickering behind it)..even > turning it on and off. You have to go back and find the pot thats got > the value 'stuck'. Zero that pot and it's fine again. It's totally > random and depends on the combination of pots and values. The actual > sound itself changes fine with the pot movement. It's just the > displaying of the values that is a bit screwed. > > Remember is the physical displaying of the values that gets stuck, > not the actual values that control the analogue parameters. They are > working fine. > > If anyone can help I'd really appreciate it, the schems are here: > http://www.matrixsynth.com/blog/media/Moog/MemorymoogSchematics/ > > The service manual is here: > http://www.retrosynth.com/docs/memorymoog/mm_service.pdf > > Apart from this fault..it seems to be almost fixed. > > Thanks, Phil. > > > > > > > > > > > --- In vintagesynthrepair@yahoogroups.com, "eggwheatis" > <eggwheatis@> wrote: > > > > A bit more fixed..:o) > > > > well actually diagnosed.. > > > > The reason all the voices were dead on one card was because a > > CEM3340 VCO chip was shorted, this pulled down the 7905 regulator > > that sits on the edge of each voice card killing the supply to the > > other CEM's. I found that a CEM3360 VCA chip was also dead on the > > same card. So after swapping a few CEM's around I know have just > one > > Oscillator 3 down. > > > > After that I noticed the VCF adsr wasnt working on one voice. A > > quick look at the schems revealed it is generated by a CEM3310 on > > the contour generator board. Sure enough I found the 3310 was dead. > > > > So that, on the face of it, appears to be the voices sorted out. Im > > sure I'll find more problems. > > > > The synth is still totally out of tune, so it will need full > > calibration. I'm not going to try that until I have located all the > > CEM chips I need. > > > > I also swapped all the HC ic's out for the correct LS versions and > > anything that isnt specified in the parts list. For instance a lot > > of the op amps are 1458's, the schematics and parts list specify > > 4558. The manual also has an addition saying you should swap any > > found to 4558. The 4558 is apparently superior. > > > > I still have the problem with the displayed pot values, I talked > > about in an earlier post(below). It drove me mad..I checked out the > > whole of the POTPOS circuit, the MUX circuit..the display > > circuits....eventually after forgetting theory, schematics and just > > randomly testing things, I found CR1 to be open on the DMUX board! > > It's a 6.2 Zener..I avent changed it yet as I was going out..but > > after checking the schems I reckon I might have solved it..it's not > > mentioned in the service manual, and it's right on the edge of the > > schems.. > > > > Thats it for now..Phil. > > > > > > > > > > > > > > > > > > --- In vintagesynthrepair@yahoogroups.com, "eggwheatis" > > <eggwheatis@> wrote: > > > > > > Fixed the hopeless switch matrix :o) there was a ribbon cable > > plugged > > > in the wrong way round into the common analogue board! Large > > repairer > > > error #5..... > > > > > > So now all the button functions work properly and I have > > Oscillator 3 > > > back!... although only 4 voices working. > > > > > > I also changed 4 of the hc138's to LS138's and the filter has now > > > started tracking the keyboard properly...I discovered two HC377's > > on > > > the digital board too..they should be LS variants again... > > > > > > So basically im left with OSC 1,2 and 3 not working on the same > > voice > > > card(3 dead cem3340's on the same card surely not? I hope) OSC 3 > > dead > > > on one other card. Hopeless autotune '0 tuned' all out of tune > > with > > > each other even on the same cards... > > > > > > Oh and the weird pot problem: when you > > > move the pots the numbers in the alpha display move up and down > > which > > > is correct, however say you turn one pot and move to another, > > > well the first pots status doesn't clear from the display, it's > > > stuck there, you can see it flicker as you move the other pot but > > > it's stuck there unless you go back and zero the original pot. > > Only > > > a few pots seem to cause this problem. > > > > > > I reckon swapping out those wrong HC ic's will cure that..maybe.. > > > > > > Im sure I'll find more problems too. It's amazing how 'previous > > > repairer error' can completely disable a synth that probably only > > had > > > a couple of faults to start with. > > > > > > Getting there... > > > > > > > > > > > > --- In vintagesynthrepair@yahoogroups.com, "eggwheatis" > > > <eggwheatis@> wrote: > > > > > > > > Well ive now got sound out of it :o) this is going to be fun > > > > though...yet again someones been in this before me that looks > > like > > > > they weren't on the ball. All the IC are in sockets...but most > > of > > > > them have been replaced sometimes with the wrong variant. > > > > > > > > No sound was indeed caused by the PSU....an electrolytic > > capacitor > > > in > > > > the +15 circuit on the DMUX board was put in backwards. > Repairer > > > > error #1. > > > > > > > > I thought I'd start by fixing the LED's on the left hand control > > > (LHC) > > > > board and the missing digit in the alpha display so I could see > > > what > > > > was going on better... > > > > > > > > The dead/stuck on LED's were caused by one of the legs of the > > ls378 > > > > at U8 on the LHC board being bent under itself in the socket. > > > > Repairer error #2. > > > > > > > > The dead digit in the alpha display was caused by a dead output > > on > > > > the LS273 at U1 on the LHC board. > > > > > > > > Anyway so now I can see and hear whats going on I have a whole > > host > > > > of new problems :o) > > > > > > > > I have no Oscillator 3 at all across the board, Osc 1 and 2 > also > > > dont > > > > work on one voice. None of the oscillators will auto-tune, i > get > > > > the '0 tuned message'. The filter self oscillates but wont > track > > > the > > > > keyboard. > > > > > > > > The switch matrix is hopeless on the LHC board, buttons > activate > > > > wrong functions basically, the appegiator doesnt work nor does > > the > > > > hold function... > > > > > > > > Things I can see right off the bat but need to get spares to > fix > > > are: > > > > All the 74ls138's on the digital board have been replaced with > > HC > > > > Cmos variants...not a good idea, these are not compatible with > > TTL > > > in > > > > most cases, so i would think they are causing a lot of problems > > > > (fingers crossed). You need LS in there or HCT at least.. > > Repairer > > > > Error #3 > > > > > > > > Also there is a TL071 missing out of a socket on the DMUX > > > board..this > > > > is connected to the auto tune circuit..buffers one of the > > outputs I > > > > think. Repairer Error #4 > > > > > > > > All in all a lot of fun! > > > > > > > > Phil. > > > > > > > > > > > > > > > > > > > > --- In vintagesynthrepair@yahoogroups.com, Philip <eggwheatis@> > > > > wrote: > > > > > > > > > > I just got a broken Memorymoog. It's really clean, near mint > > in > > > > fact, but not working. Half the reason I bought it is because I > > > like > > > > a challenge :o) ..I haven't even opened it up yet so I thought > > I'd > > > > post up the problems to see if anyone has an idea. > > > > >  > > > > > It boots up ok, but makes very little sound the most you get > > out > > > of > > > > it is a thump or slight squeak when you hit a key, the same > > pitch > > > > wherever you hit. The digital side seem to be mostly working. > > > > >  > > > > > If you hit autotune it comes back with '0 tuned' so it can't > > tune > > > > any of the oscillators probably because it cant 'hear' them so > > to > > > > speak. > > > > >  > > > > > First thoughts are some kind of DAC problem. > > > > >  > > > > > 2: All the LED's on the left hand side don't work at all but > > the > > > > buttons do. A few are just stuck on all the time, again the > > buttons > > > > work. > > > > >  > > > > > 3: one digit on the alpha/numeric display is barely visible. > > > > >  > > > > > 4: this is a slightly weird one which is hard to describe, > > when > > > you > > > > move the pots the numbers in the alpha display move up and down > > > which > > > > is correct., however say you turn one pot and move to another, > > > > well the first pots status doesn't clear from the display, > it's > > > > stuck there, you can see it flicker as you move the other pot > > but > > > > it's stuck there unless you go back and zero the original pot.
> > > Only > > > > a few pots seem to cause this problem. > > > > >  > > > > > Any ideas would be helpful. Obviously the first thing im > going > > to > > > > check is the PSU when I open it up later. > > > > >  > > > > > Thanks, Phil. > > > > >  > > > > > > > > > > Send instant messages to your online friends > > > > http://uk.messenger.yahoo.com > > > > > > > > > > > > > > >
2008-09-04 by eggwheatis
I also was going to add that again, a very large percentage of these problems have been caused by someone who basically didnt have a clue. It probably started off as a minor problem and snowballed.. Actually I can talk...A friend said, 'hey the Hi-hat sounds bad on my 606 can you fix it?' Sure I said...easy right? Well so far I managed to not fix it and accidently short out something else..now it's sounding a lot sicker than before... But thats another thread! TBC. --- In vintagesynthrepair@yahoogroups.com, "eggwheatis" <eggwheatis@...> wrote: > > Phew..I fixed the pot problem, well I think I have. > > I ended up taking every board out and going through them with a fine > toothed comb, I cleaned any surplus flux off, checked > everything..scoped everything. I just could not find it. > > Then something occured to me..like many things do when repairing > stuff!..on the schematics there is an LF351 op-amp on the output of > the DAC..but it the actual socket was a TL071 which should be fine, > and i had already swapped it out..anyway it is an equivalent and is > even mentioned in parenthesis on the parts sheet next to LF351, as is > TL072 as an equivalent for LF353. In fact my memorymoog has TL072'a > and TL)71's throughout. > > Now I know how sensitive digital circuits are to 'equivalents' so I > put in an LF351 and bingo....it was fixed! Or so I thought basically > I did it again once after playing around with it after an hour..now > normally it did it every 30 seconds so it is 99% better and hasn't > done it again. > > Maybe the DAC is faulty itself but I still don't understand how this > would effect the displayed pot values. Surely that's down to the A/D? > > Also with good news comes bad...after fixing that problem I rechecked > the voices..I had lost another voice! AFter finding another red hot > regulator on a voice board I found all three CEM3340's were shorted!! > Arggh!! I was feeling pretty sick considering how expensive they are! > > I must have shorted something out while trying to fix the pot > problem...oh well.. > > So anyway I've got 5 CEM3340's on the way(one spare), a 3310 and a > 3360. After calibration that should be it. Fingers crossed X > > > --- In vintagesynthrepair@yahoogroups.com, "eggwheatis" > <eggwheatis@> wrote: > > > > Well this (hopefully)last problem is proving to be really difficult > > to solve. It wasnt the Zener even though it was bad. It acts as a > > regulator for the +10 vdc to the DAC from the Control boards... It > > was causing it to sit at 11.5 vdc. Changing it did nothing. > > > > It's one of those niggling annoying problems that seems to be > > undetectable...its driving me nuts..I'll try to explain it better. > > > > Basically you turn a pot on this synth and the pots value is shown > on > > the alpha/dec LED display, you turn the second pot the display > > instantly shows that pots value..so far so good...but after a few > > turns of various pots, it will stick on a value and won't change > with > > the new pot movements, pressing buttons, turning other pots wont > get > > rid of it(you can see the correct values flickering behind > it)..even > > turning it on and off. You have to go back and find the pot thats > got > > the value 'stuck'. Zero that pot and it's fine again. It's totally > > random and depends on the combination of pots and values. The > actual > > sound itself changes fine with the pot movement. It's just the > > displaying of the values that is a bit screwed. > > > > Remember is the physical displaying of the values that gets stuck, > > not the actual values that control the analogue parameters. They > are > > working fine. > > > > If anyone can help I'd really appreciate it, the schems are here: > > http://www.matrixsynth.com/blog/media/Moog/MemorymoogSchematics/ > > > > The service manual is here: > > http://www.retrosynth.com/docs/memorymoog/mm_service.pdf > > > > Apart from this fault..it seems to be almost fixed. > > > > Thanks, Phil. > > > > > > > > > > > > > > > > > > > > > > --- In vintagesynthrepair@yahoogroups.com, "eggwheatis" > > <eggwheatis@> wrote: > > > > > > A bit more fixed..:o) > > > > > > well actually diagnosed.. > > > > > > The reason all the voices were dead on one card was because a > > > CEM3340 VCO chip was shorted, this pulled down the 7905 regulator > > > that sits on the edge of each voice card killing the supply to > the > > > other CEM's. I found that a CEM3360 VCA chip was also dead on the > > > same card. So after swapping a few CEM's around I know have just > > one > > > Oscillator 3 down. > > > > > > After that I noticed the VCF adsr wasnt working on one voice. A > > > quick look at the schems revealed it is generated by a CEM3310 on > > > the contour generator board. Sure enough I found the 3310 was > dead. > > > > > > So that, on the face of it, appears to be the voices sorted out. > Im > > > sure I'll find more problems. > > > > > > The synth is still totally out of tune, so it will need full > > > calibration. I'm not going to try that until I have located all > the > > > CEM chips I need. > > > > > > I also swapped all the HC ic's out for the correct LS versions > and > > > anything that isnt specified in the parts list. For instance a > lot > > > of the op amps are 1458's, the schematics and parts list specify > > > 4558. The manual also has an addition saying you should swap any > > > found to 4558. The 4558 is apparently superior. > > > > > > I still have the problem with the displayed pot values, I talked > > > about in an earlier post(below). It drove me mad..I checked out > the > > > whole of the POTPOS circuit, the MUX circuit..the display > > > circuits....eventually after forgetting theory, schematics and > just > > > randomly testing things, I found CR1 to be open on the DMUX > board! > > > It's a 6.2 Zener..I avent changed it yet as I was going out..but > > > after checking the schems I reckon I might have solved it..it's > not > > > mentioned in the service manual, and it's right on the edge of > the > > > schems.. > > > > > > Thats it for now..Phil. > > > > > > > > > > > > > > > > > > > > > > > > > > > --- In vintagesynthrepair@yahoogroups.com, "eggwheatis" > > > <eggwheatis@> wrote: > > > > > > > > Fixed the hopeless switch matrix :o) there was a ribbon cable > > > plugged > > > > in the wrong way round into the common analogue board! Large > > > repairer > > > > error #5..... > > > > > > > > So now all the button functions work properly and I have > > > Oscillator 3 > > > > back!... although only 4 voices working. > > > > > > > > I also changed 4 of the hc138's to LS138's and the filter has > now > > > > started tracking the keyboard properly...I discovered two > HC377's > > > on > > > > the digital board too..they should be LS variants again... > > > > > > > > So basically im left with OSC 1,2 and 3 not working on the same > > > voice > > > > card(3 dead cem3340's on the same card surely not? I hope) OSC > 3 > > > dead > > > > on one other card. Hopeless autotune '0 tuned' all out of tune > > > with > > > > each other even on the same cards... > > > > > > > > Oh and the weird pot problem: when you > > > > move the pots the numbers in the alpha display move up and down > > > which > > > > is correct, however say you turn one pot and move to another, > > > > well the first pots status doesn't clear from the display, it's > > > > stuck there, you can see it flicker as you move the other pot > but > > > > it's stuck there unless you go back and zero the original pot. > > > Only > > > > a few pots seem to cause this problem. > > > > > > > > I reckon swapping out those wrong HC ic's will cure > that..maybe.. > > > > > > > > Im sure I'll find more problems too. It's amazing how 'previous > > > > repairer error' can completely disable a synth that probably > only > > > had > > > > a couple of faults to start with. > > > > > > > > Getting there... > > > > > > > > > > > > > > > > --- In vintagesynthrepair@yahoogroups.com, "eggwheatis" > > > > <eggwheatis@> wrote: > > > > > > > > > > Well ive now got sound out of it :o) this is going to be fun > > > > > though...yet again someones been in this before me that looks > > > like > > > > > they weren't on the ball. All the IC are in sockets...but > most > > > of > > > > > them have been replaced sometimes with the wrong variant. > > > > > > > > > > No sound was indeed caused by the PSU....an electrolytic > > > capacitor > > > > in > > > > > the +15 circuit on the DMUX board was put in backwards. > > Repairer > > > > > error #1. > > > > > > > > > > I thought I'd start by fixing the LED's on the left hand > control > > > > (LHC) > > > > > board and the missing digit in the alpha display so I could > see > > > > what > > > > > was going on better... > > > > > > > > > > The dead/stuck on LED's were caused by one of the legs of the > > > ls378 > > > > > at U8 on the LHC board being bent under itself in the socket. > > > > > Repairer error #2. > > > > > > > > > > The dead digit in the alpha display was caused by a dead > output > > > on > > > > > the LS273 at U1 on the LHC board. > > > > > > > > > > Anyway so now I can see and hear whats going on I have a > whole > > > host > > > > > of new problems :o) > > > > > > > > > > I have no Oscillator 3 at all across the board, Osc 1 and 2 > > also > > > > dont > > > > > work on one voice. None of the oscillators will auto-tune, i > > get > > > > > the '0 tuned message'. The filter self oscillates but wont > > track > > > > the > > > > > keyboard. > > > > > > > > > > The switch matrix is hopeless on the LHC board, buttons > > activate > > > > > wrong functions basically, the appegiator doesnt work nor > does > > > the > > > > > hold function... > > > > > > > > > > Things I can see right off the bat but need to get spares to > > fix > > > > are: > > > > > All the 74ls138's on the digital board have been replaced > with > > > HC > > > > > Cmos variants...not a good idea, these are not compatible > with > > > TTL > > > > in > > > > > most cases, so i would think they are causing a lot of > problems > > > > > (fingers crossed). You need LS in there or HCT at least.. > > > Repairer > > > > > Error #3 > > > > > > > > > > Also there is a TL071 missing out of a socket on the DMUX > > > > board..this > > > > > is connected to the auto tune circuit..buffers one of the > > > outputs I > > > > > think. Repairer Error #4 > > > > > > > > > > All in all a lot of fun! > > > > > > > > > > Phil. > > > > > > > > > > > > > > > > > > > > > > > > > --- In vintagesynthrepair@yahoogroups.com, Philip > <eggwheatis@> > > > > > wrote: > > > > > > > > > > > > I just got a broken Memorymoog. It's really clean, near > mint > > > in > > > > > fact, but not working. Half the reason I bought it is because > I > > > > like > > > > > a challenge :o) ..I haven't even opened it up yet so I > thought > > > I'd > > > > > post up the problems to see if anyone has an idea. > > > > > >  > > > > > > It boots up ok, but makes very little sound the most you > get > > > out > > > > of > > > > > it is a thump or slight squeak when you hit a key, the same > > > pitch > > > > > wherever you hit. The digital side seem to be mostly working. > > > > > >  > > > > > > If you hit autotune it comes back with '0 tuned' so it > can't > > > tune > > > > > any of the oscillators probably because it cant 'hear' them > so > > > to > > > > > speak. > > > > > >  > > > > > > First thoughts are some kind of DAC problem. > > > > > >  > > > > > > 2: All the LED's on the left hand side don't work at all > but > > > the > > > > > buttons do. A few are just stuck on all the time, again the > > > buttons > > > > > work. > > > > > >  > > > > > > 3: one digit on the alpha/numeric display is barely visible. > > > > > >  > > > > > > 4: this is a slightly weird one which is hard to describe, > > > when > > > > you > > > > > move the pots the numbers in the alpha display move up and > down > > > > which > > > > > is correct., however say you turn one pot and move to > another, > > > > > well the first pots status doesn't clear from the display, > > it's > > > > > stuck there, you can see it flicker as you move the other pot
> > > but > > > > > it's stuck there unless you go back and zero the original > pot. > > > > Only > > > > > a few pots seem to cause this problem. > > > > > >  > > > > > > Any ideas would be helpful. Obviously the first thing im > > going > > > to > > > > > check is the PSU when I open it up later. > > > > > >  > > > > > > Thanks, Phil. > > > > > >  > > > > > > > > > > > > Send instant messages to your online friends > > > > > http://uk.messenger.yahoo.com > > > > > > > > > > > > > > > > > > > > >
2008-10-21 by gerryrdahl
Hi Phil, How has the Memorymoog turned out? Did the replacement CEM's and a calibration finish her up? Would like to know. Thanks. GD --- In vintagesynthrepair@yahoogroups.com, "eggwheatis" <eggwheatis@...> wrote: > > Phew..I fixed the pot problem, well I think I have. > > I ended up taking every board out and going through them with a fine > toothed comb, I cleaned any surplus flux off, checked > everything..scoped everything. I just could not find it. > > Then something occured to me..like many things do when repairing > stuff!..on the schematics there is an LF351 op-amp on the output of > the DAC..but it the actual socket was a TL071 which should be fine, > and i had already swapped it out..anyway it is an equivalent and is > even mentioned in parenthesis on the parts sheet next to LF351, as is > TL072 as an equivalent for LF353. In fact my memorymoog has TL072'a > and TL)71's throughout. > > Now I know how sensitive digital circuits are to 'equivalents' so I > put in an LF351 and bingo....it was fixed! Or so I thought basically > I did it again once after playing around with it after an hour..now > normally it did it every 30 seconds so it is 99% better and hasn't > done it again. > > Maybe the DAC is faulty itself but I still don't understand how this > would effect the displayed pot values. Surely that's down to the A/D? > > Also with good news comes bad...after fixing that problem I rechecked > the voices..I had lost another voice! AFter finding another red hot > regulator on a voice board I found all three CEM3340's were shorted!! > Arggh!! I was feeling pretty sick considering how expensive they are! > > I must have shorted something out while trying to fix the pot > problem...oh well.. > > So anyway I've got 5 CEM3340's on the way(one spare), a 3310 and a > 3360. After calibration that should be it. Fingers crossed X > > > --- In vintagesynthrepair@yahoogroups.com, "eggwheatis" > <eggwheatis@> wrote: > > > > Well this (hopefully)last problem is proving to be really difficult > > to solve. It wasnt the Zener even though it was bad. It acts as a > > regulator for the +10 vdc to the DAC from the Control boards... It > > was causing it to sit at 11.5 vdc. Changing it did nothing. > > > > It's one of those niggling annoying problems that seems to be > > undetectable...its driving me nuts..I'll try to explain it better. > > > > Basically you turn a pot on this synth and the pots value is shown > on > > the alpha/dec LED display, you turn the second pot the display > > instantly shows that pots value..so far so good...but after a few > > turns of various pots, it will stick on a value and won't change > with > > the new pot movements, pressing buttons, turning other pots wont > get > > rid of it(you can see the correct values flickering behind > it)..even > > turning it on and off. You have to go back and find the pot thats > got > > the value 'stuck'. Zero that pot and it's fine again. It's totally > > random and depends on the combination of pots and values. The > actual > > sound itself changes fine with the pot movement. It's just the > > displaying of the values that is a bit screwed. > > > > Remember is the physical displaying of the values that gets stuck, > > not the actual values that control the analogue parameters. They > are > > working fine. > > > > If anyone can help I'd really appreciate it, the schems are here: > > http://www.matrixsynth.com/blog/media/Moog/MemorymoogSchematics/ > > > > The service manual is here: > > http://www.retrosynth.com/docs/memorymoog/mm_service.pdf > > > > Apart from this fault..it seems to be almost fixed. > > > > Thanks, Phil. > > > > > > > > > > > > > > > > > > > > > > --- In vintagesynthrepair@yahoogroups.com, "eggwheatis" > > <eggwheatis@> wrote: > > > > > > A bit more fixed..:o) > > > > > > well actually diagnosed.. > > > > > > The reason all the voices were dead on one card was because a > > > CEM3340 VCO chip was shorted, this pulled down the 7905 regulator > > > that sits on the edge of each voice card killing the supply to > the > > > other CEM's. I found that a CEM3360 VCA chip was also dead on the > > > same card. So after swapping a few CEM's around I know have just > > one > > > Oscillator 3 down. > > > > > > After that I noticed the VCF adsr wasnt working on one voice. A > > > quick look at the schems revealed it is generated by a CEM3310 on > > > the contour generator board. Sure enough I found the 3310 was > dead. > > > > > > So that, on the face of it, appears to be the voices sorted out. > Im > > > sure I'll find more problems. > > > > > > The synth is still totally out of tune, so it will need full > > > calibration. I'm not going to try that until I have located all > the > > > CEM chips I need. > > > > > > I also swapped all the HC ic's out for the correct LS versions > and > > > anything that isnt specified in the parts list. For instance a > lot > > > of the op amps are 1458's, the schematics and parts list specify > > > 4558. The manual also has an addition saying you should swap any > > > found to 4558. The 4558 is apparently superior. > > > > > > I still have the problem with the displayed pot values, I talked > > > about in an earlier post(below). It drove me mad..I checked out > the > > > whole of the POTPOS circuit, the MUX circuit..the display > > > circuits....eventually after forgetting theory, schematics and > just > > > randomly testing things, I found CR1 to be open on the DMUX > board! > > > It's a 6.2 Zener..I avent changed it yet as I was going out..but > > > after checking the schems I reckon I might have solved it..it's > not > > > mentioned in the service manual, and it's right on the edge of > the > > > schems.. > > > > > > Thats it for now..Phil. > > > > > > > > > > > > > > > > > > > > > > > > > > > --- In vintagesynthrepair@yahoogroups.com, "eggwheatis" > > > <eggwheatis@> wrote: > > > > > > > > Fixed the hopeless switch matrix :o) there was a ribbon cable > > > plugged > > > > in the wrong way round into the common analogue board! Large > > > repairer > > > > error #5..... > > > > > > > > So now all the button functions work properly and I have > > > Oscillator 3 > > > > back!... although only 4 voices working. > > > > > > > > I also changed 4 of the hc138's to LS138's and the filter has > now > > > > started tracking the keyboard properly...I discovered two > HC377's > > > on > > > > the digital board too..they should be LS variants again... > > > > > > > > So basically im left with OSC 1,2 and 3 not working on the same > > > voice > > > > card(3 dead cem3340's on the same card surely not? I hope) OSC > 3 > > > dead > > > > on one other card. Hopeless autotune '0 tuned' all out of tune > > > with > > > > each other even on the same cards... > > > > > > > > Oh and the weird pot problem: when you > > > > move the pots the numbers in the alpha display move up and down > > > which > > > > is correct, however say you turn one pot and move to another, > > > > well the first pots status doesn't clear from the display, it's > > > > stuck there, you can see it flicker as you move the other pot > but > > > > it's stuck there unless you go back and zero the original pot. > > > Only > > > > a few pots seem to cause this problem. > > > > > > > > I reckon swapping out those wrong HC ic's will cure > that..maybe.. > > > > > > > > Im sure I'll find more problems too. It's amazing how 'previous > > > > repairer error' can completely disable a synth that probably > only > > > had > > > > a couple of faults to start with. > > > > > > > > Getting there... > > > > > > > > > > > > > > > > --- In vintagesynthrepair@yahoogroups.com, "eggwheatis" > > > > <eggwheatis@> wrote: > > > > > > > > > > Well ive now got sound out of it :o) this is going to be fun > > > > > though...yet again someones been in this before me that looks > > > like > > > > > they weren't on the ball. All the IC are in sockets...but > most > > > of > > > > > them have been replaced sometimes with the wrong variant. > > > > > > > > > > No sound was indeed caused by the PSU....an electrolytic > > > capacitor > > > > in > > > > > the +15 circuit on the DMUX board was put in backwards. > > Repairer > > > > > error #1. > > > > > > > > > > I thought I'd start by fixing the LED's on the left hand > control > > > > (LHC) > > > > > board and the missing digit in the alpha display so I could > see > > > > what > > > > > was going on better... > > > > > > > > > > The dead/stuck on LED's were caused by one of the legs of the > > > ls378 > > > > > at U8 on the LHC board being bent under itself in the socket. > > > > > Repairer error #2. > > > > > > > > > > The dead digit in the alpha display was caused by a dead > output > > > on > > > > > the LS273 at U1 on the LHC board. > > > > > > > > > > Anyway so now I can see and hear whats going on I have a > whole > > > host > > > > > of new problems :o) > > > > > > > > > > I have no Oscillator 3 at all across the board, Osc 1 and 2 > > also > > > > dont > > > > > work on one voice. None of the oscillators will auto-tune, i > > get > > > > > the '0 tuned message'. The filter self oscillates but wont > > track > > > > the > > > > > keyboard. > > > > > > > > > > The switch matrix is hopeless on the LHC board, buttons > > activate > > > > > wrong functions basically, the appegiator doesnt work nor > does > > > the > > > > > hold function... > > > > > > > > > > Things I can see right off the bat but need to get spares to > > fix > > > > are: > > > > > All the 74ls138's on the digital board have been replaced > with > > > HC > > > > > Cmos variants...not a good idea, these are not compatible > with > > > TTL > > > > in > > > > > most cases, so i would think they are causing a lot of > problems > > > > > (fingers crossed). You need LS in there or HCT at least.. > > > Repairer > > > > > Error #3 > > > > > > > > > > Also there is a TL071 missing out of a socket on the DMUX > > > > board..this > > > > > is connected to the auto tune circuit..buffers one of the > > > outputs I > > > > > think. Repairer Error #4 > > > > > > > > > > All in all a lot of fun! > > > > > > > > > > Phil. > > > > > > > > > > > > > > > > > > > > > > > > > --- In vintagesynthrepair@yahoogroups.com, Philip > <eggwheatis@> > > > > > wrote: > > > > > > > > > > > > I just got a broken Memorymoog. It's really clean, near > mint > > > in > > > > > fact, but not working. Half the reason I bought it is because > I > > > > like > > > > > a challenge :o) ..I haven't even opened it up yet so I > thought > > > I'd > > > > > post up the problems to see if anyone has an idea. > > > > > >  > > > > > > It boots up ok, but makes very little sound the most you > get > > > out > > > > of > > > > > it is a thump or slight squeak when you hit a key, the same > > > pitch > > > > > wherever you hit. The digital side seem to be mostly working. > > > > > >  > > > > > > If you hit autotune it comes back with '0 tuned' so it > can't > > > tune > > > > > any of the oscillators probably because it cant 'hear' them > so > > > to > > > > > speak. > > > > > >  > > > > > > First thoughts are some kind of DAC problem. > > > > > >  > > > > > > 2: All the LED's on the left hand side don't work at all > but > > > the > > > > > buttons do. A few are just stuck on all the time, again the > > > buttons > > > > > work. > > > > > >  > > > > > > 3: one digit on the alpha/numeric display is barely visible. > > > > > >  > > > > > > 4: this is a slightly weird one which is hard to describe, > > > when > > > > you > > > > > move the pots the numbers in the alpha display move up and > down > > > > which > > > > > is correct., however say you turn one pot and move to > another, > > > > > well the first pots status doesn't clear from the display, > > it's > > > > > stuck there, you can see it flicker as you move the other pot
> > > but > > > > > it's stuck there unless you go back and zero the original > pot. > > > > Only > > > > > a few pots seem to cause this problem. > > > > > >  > > > > > > Any ideas would be helpful. Obviously the first thing im > > going > > > to > > > > > check is the PSU when I open it up later. > > > > > >  > > > > > > Thanks, Phil. > > > > > >  > > > > > > > > > > > > Send instant messages to your online friends > > > > > http://uk.messenger.yahoo.com > > > > > > > > > > > > > > > > > > > > >
2008-10-31 by Philip
Hi, i just started back tonight on it.... After a a very expensive purchase of some CEM ic's I have all the voices working on it now. I was seriously scared off putting the new IC's in in case they died again...but I bit the bullet and all seems fine. Phew! SO now I have a fully working but seriously out of tune Memorymoog. The autotune wont tune it..too far out. I just get '0 tuned' I checked the calibration out in the manual and I found it a bit confusing... Has anyone got any tips on calibrating it? Thanks, Phil. --- On Tue, 21/10/08, gerryrdahl <gerryrdahl@...> wrote: From: gerryrdahl <gerryrdahl@yahoo.com> Subject: [vintagesynthrepair] Re: Memorymoog repair To: vintagesynthrepair@yahoogroups.com Date: Tuesday, 21 October, 2008, 4:13 AM Hi Phil, How has the Memorymoog turned out? Did the replacement CEM's and a calibration finish her up? Would like to know. Thanks. GD --- In vintagesynthrepair@ yahoogroups. com, "eggwheatis" <eggwheatis@ ...> wrote: > > Phew..I fixed the pot problem, well I think I have. > > I ended up taking every board out and going through them with a fine > toothed comb, I cleaned any surplus flux off, checked > everything.. scoped everything. I just could not find it. > > Then something occured to me..like many things do when repairing > stuff!..on the schematics there is an LF351 op-amp on the output of > the DAC..but it the actual socket was a TL071 which should be fine, > and i had already swapped it out..anyway it is an equivalent and is > even mentioned in parenthesis on the parts sheet next to LF351, as is > TL072 as an equivalent for LF353. In fact my memorymoog has TL072'a > and TL)71's throughout. > > Now I know how sensitive digital circuits are to 'equivalents' so I > put in an LF351 and bingo....it was fixed! Or so I thought basically > I did it again once after playing around with it after an hour..now > normally it did it every 30 seconds so it is 99% better and hasn't > done it again. > > Maybe the DAC is faulty itself but I still don't understand how this > would effect the displayed pot values. Surely that's down to the A/D? > > Also with good news comes bad...after fixing that problem I rechecked > the voices..I had lost another voice! AFter finding another red hot > regulator on a voice board I found all three CEM3340's were shorted!! > Arggh!! I was feeling pretty sick considering how expensive they are! > > I must have shorted something out while trying to fix the pot > problem...oh well.. > > So anyway I've got 5 CEM3340's on the way(one spare), a 3310 and a > 3360. After calibration that should be it. Fingers crossed X > > > --- In vintagesynthrepair@ yahoogroups. com, "eggwheatis" > <eggwheatis@ > wrote: > > > > Well this (hopefully)last problem is proving to be really difficult > > to solve. It wasnt the Zener even though it was bad. It acts as a > > regulator for the +10 vdc to the DAC from the Control boards... It > > was causing it to sit at 11.5 vdc. Changing it did nothing. > > > > It's one of those niggling annoying problems that seems to be > > undetectable. ..its driving me nuts..I'll try to explain it better. > > > > Basically you turn a pot on this synth and the pots value is shown > on > > the alpha/dec LED display, you turn the second pot the display > > instantly shows that pots value..so far so good...but after a few > > turns of various pots, it will stick on a value and won't change > with > > the new pot movements, pressing buttons, turning other pots wont > get > > rid of it(you can see the correct values flickering behind > it)..even > > turning it on and off. You have to go back and find the pot thats > got > > the value 'stuck'. Zero that pot and it's fine again. It's totally > > random and depends on the combination of pots and values. The > actual > > sound itself changes fine with the pot movement. It's just the > > displaying of the values that is a bit screwed. > > > > Remember is the physical displaying of the values that gets stuck, > > not the actual values that control the analogue parameters. They > are > > working fine. > > > > If anyone can help I'd really appreciate it, the schems are here: > > http://www.matrixsy nth.com/blog/ media/Moog/ MemorymoogSchema tics/ > > > > The service manual is here: > > http://www.retrosyn th.com/docs/ memorymoog/ mm_service. pdf > > > > Apart from this fault..it seems to be almost fixed. > > > > Thanks, Phil. > > > > > > > > > > > > > > > > > > > > > > --- In vintagesynthrepair@ yahoogroups. com, "eggwheatis" > > <eggwheatis@ > wrote: > > > > > > A bit more fixed..:o) > > > > > > well actually diagnosed.. > > > > > > The reason all the voices were dead on one card was because a > > > CEM3340 VCO chip was shorted, this pulled down the 7905 regulator > > > that sits on the edge of each voice card killing the supply to > the > > > other CEM's. I found that a CEM3360 VCA chip was also dead on the > > > same card. So after swapping a few CEM's around I know have just > > one > > > Oscillator 3 down. > > > > > > After that I noticed the VCF adsr wasnt working on one voice. A > > > quick look at the schems revealed it is generated by a CEM3310 on > > > the contour generator board. Sure enough I found the 3310 was > dead. > > > > > > So that, on the face of it, appears to be the voices sorted out. > Im > > > sure I'll find more problems. > > > > > > The synth is still totally out of tune, so it will need full > > > calibration. I'm not going to try that until I have located all > the > > > CEM chips I need. > > > > > > I also swapped all the HC ic's out for the correct LS versions > and > > > anything that isnt specified in the parts list. For instance a > lot > > > of the op amps are 1458's, the schematics and parts list specify > > > 4558. The manual also has an addition saying you should swap any > > > found to 4558. The 4558 is apparently superior. > > > > > > I still have the problem with the displayed pot values, I talked > > > about in an earlier post(below). It drove me mad..I checked out > the > > > whole of the POTPOS circuit, the MUX circuit..the display > > > circuits.... eventually after forgetting theory, schematics and > just > > > randomly testing things, I found CR1 to be open on the DMUX > board! > > > It's a 6.2 Zener..I avent changed it yet as I was going out..but > > > after checking the schems I reckon I might have solved it..it's > not > > > mentioned in the service manual, and it's right on the edge of > the > > > schems.. > > > > > > Thats it for now..Phil. > > > > > > > > > > > > > > > > > > > > > > > > > > > --- In vintagesynthrepair@ yahoogroups. com, "eggwheatis" > > > <eggwheatis@ > wrote: > > > > > > > > Fixed the hopeless switch matrix :o) there was a ribbon cable > > > plugged > > > > in the wrong way round into the common analogue board! Large > > > repairer > > > > error #5..... > > > > > > > > So now all the button functions work properly and I have > > > Oscillator 3 > > > > back!... although only 4 voices working. > > > > > > > > I also changed 4 of the hc138's to LS138's and the filter has > now > > > > started tracking the keyboard properly...I discovered two > HC377's > > > on > > > > the digital board too..they should be LS variants again... > > > > > > > > So basically im left with OSC 1,2 and 3 not working on the same > > > voice > > > > card(3 dead cem3340's on the same card surely not? I hope) OSC > 3 > > > dead > > > > on one other card. Hopeless autotune '0 tuned' all out of tune > > > with > > > > each other even on the same cards... > > > > > > > > Oh and the weird pot problem: when you > > > > move the pots the numbers in the alpha display move up and down > > > which > > > > is correct, however say you turn one pot and move to another, > > > > well the first pots status doesn't clear from the display, it's > > > > stuck there, you can see it flicker as you move the other pot > but > > > > it's stuck there unless you go back and zero the original pot. > > > Only > > > > a few pots seem to cause this problem. > > > > > > > > I reckon swapping out those wrong HC ic's will cure > that..maybe. . > > > > > > > > Im sure I'll find more problems too. It's amazing how 'previous > > > > repairer error' can completely disable a synth that probably > only > > > had > > > > a couple of faults to start with. > > > > > > > > Getting there... > > > > > > > > > > > > > > > > --- In vintagesynthrepair@ yahoogroups. com, "eggwheatis" > > > > <eggwheatis@ > wrote: > > > > > > > > > > Well ive now got sound out of it :o) this is going to be fun > > > > > though...yet again someones been in this before me that looks > > > like > > > > > they weren't on the ball. All the IC are in sockets...but > most > > > of > > > > > them have been replaced sometimes with the wrong variant. > > > > > > > > > > No sound was indeed caused by the PSU....an electrolytic > > > capacitor > > > > in > > > > > the +15 circuit on the DMUX board was put in backwards. > > Repairer > > > > > error #1. > > > > > > > > > > I thought I'd start by fixing the LED's on the left hand > control > > > > (LHC) > > > > > board and the missing digit in the alpha display so I could > see > > > > what > > > > > was going on better... > > > > > > > > > > The dead/stuck on LED's were caused by one of the legs of the > > > ls378 > > > > > at U8 on the LHC board being bent under itself in the socket. > > > > > Repairer error #2. > > > > > > > > > > The dead digit in the alpha display was caused by a dead > output > > > on > > > > > the LS273 at U1 on the LHC board. > > > > > > > > > > Anyway so now I can see and hear whats going on I have a > whole > > > host > > > > > of new problems :o) > > > > > > > > > > I have no Oscillator 3 at all across the board, Osc 1 and 2 > > also > > > > dont > > > > > work on one voice. None of the oscillators will auto-tune, i > > get > > > > > the '0 tuned message'. The filter self oscillates but wont > > track > > > > the > > > > > keyboard. > > > > > > > > > > The switch matrix is hopeless on the LHC board, buttons > > activate > > > > > wrong functions basically, the appegiator doesnt work nor > does > > > the > > > > > hold function... > > > > > > > > > > Things I can see right off the bat but need to get spares to > > fix > > > > are: > > > > > All the 74ls138's on the digital board have been replaced > with > > > HC > > > > > Cmos variants...not a good idea, these are not compatible > with > > > TTL > > > > in > > > > > most cases, so i would think they are causing a lot of > problems > > > > > (fingers crossed). You need LS in there or HCT at least.. > > > Repairer > > > > > Error #3 > > > > > > > > > > Also there is a TL071 missing out of a socket on the DMUX > > > > board..this > > > > > is connected to the auto tune circuit..buffers one of the > > > outputs I > > > > > think. Repairer Error #4 > > > > > > > > > > All in all a lot of fun! > > > > > > > > > > Phil. > > > > > > > > > > > > > > > > > > > > > > > > > --- In vintagesynthrepair@ yahoogroups. com, Philip > <eggwheatis@ > > > > > > wrote: > > > > > > > > > > > > I just got a broken Memorymoog. It's really clean, near > mint > > > in > > > > > fact, but not working. Half the reason I bought it is because > I > > > > like > > > > > a challenge :o) ..I haven't even opened it up yet so I > thought > > > I'd > > > > > post up the problems to see if anyone has an idea. > > > > > >  > > > > > > It boots up ok, but makes very little sound the most you > get > > > out > > > > of > > > > > it is a thump or slight squeak when you hit a key, the same > > > pitch > > > > > wherever you hit. The digital side seem to be mostly working. > > > > > >  > > > > > > If you hit autotune it comes back with '0 tuned' so it > can't > > > tune > > > > > any of the oscillators probably because it cant 'hear' them > so > > > to > > > > > speak. > > > > > >  > > > > > > First thoughts are some kind of DAC problem. > > > > > >  > > > > > > 2: All the LED's on the left hand side don't work at all > but > > > the > > > > > buttons do. A few are just stuck on all the time, again the > > > buttons > > > > > work. > > > > > >  > > > > > > 3: one digit on the alpha/numeric display is barely visible. > > > > > >  > > > > > > 4: this is a slightly weird one which is hard to describe, > > > when > > > > you > > > > > move the pots the numbers in the alpha display move up and > down > > > > which > > > > > is correct., however say you turn one pot and move to > another, > > > > > well the first pots status doesn't clear from the display, > > it's > > > > > stuck there, you can see it flicker as you move the other pot
> > > but > > > > > it's stuck there unless you go back and zero the original > pot. > > > > Only > > > > > a few pots seem to cause this problem. > > > > > >  > > > > > > Any ideas would be helpful. Obviously the first thing im > > going > > > to > > > > > check is the PSU when I open it up later. > > > > > >  > > > > > > Thanks, Phil. > > > > > >  > > > > > > > > > > > > Send instant messages to your online friends > > > > > http://uk.messenger .yahoo.com > > > > > > > > > > > > > > > > > > > > >
2008-11-01 by gerryrdahl
Hi Phil, What are the readouts for the Osc's? When you press c-7-enter-enter-1-1, what does the display read? If it reads dead osc or LOW, check the others and see what you get. You may have a CTC osc scanning problem, where the CTC cannot count (or check the tuning) on the osc's. Also what version firmware do you have? When you do a c-0-enter all the leds blink, in the patch readout will be a flashing number, this is the version. Also check the pitch bend and fine tune circuit. These are supposed to be disabled during autotune. if not then the MM will not tune. Let us know. GD --- In vintagesynthrepair@yahoogroups.com, Philip <eggwheatis@...> wrote: > > Hi, i just started back tonight on it.... After a a very expensive purchase of some CEM ic's I have all the voices working on it now. >  > I was seriously scared off putting the new IC's in in case they died again...but I bit the bullet and all seems fine. Phew! >  > SO now I have a fully working but seriously out of tune Memorymoog. The autotune wont tune it..too far out. I just get '0 tuned' >  > I checked the calibration out in the manual and I found it a bit confusing... >  > Has anyone got any tips on calibrating it? >  > Thanks, Phil. >  > > > --- On Tue, 21/10/08, gerryrdahl <gerryrdahl@...> wrote: > > From: gerryrdahl <gerryrdahl@...> > Subject: [vintagesynthrepair] Re: Memorymoog repair > To: vintagesynthrepair@yahoogroups.com > Date: Tuesday, 21 October, 2008, 4:13 AM > > > > > > > Hi Phil, > How has the Memorymoog turned out? > > Did the replacement CEM's and a calibration finish her up? > > Would like to know. > > Thanks. > GD > > --- In vintagesynthrepair@ yahoogroups. com, "eggwheatis" > <eggwheatis@ ...> wrote: > > > > Phew..I fixed the pot problem, well I think I have. > > > > I ended up taking every board out and going through them with a > fine > > toothed comb, I cleaned any surplus flux off, checked > > everything.. scoped everything. I just could not find it. > > > > Then something occured to me..like many things do when repairing > > stuff!..on the schematics there is an LF351 op-amp on the output > of > > the DAC..but it the actual socket was a TL071 which should be > fine, > > and i had already swapped it out..anyway it is an equivalent and > is > > even mentioned in parenthesis on the parts sheet next to LF351, as > is > > TL072 as an equivalent for LF353. In fact my memorymoog has > TL072'a > > and TL)71's throughout. > > > > Now I know how sensitive digital circuits are to 'equivalents' so > I > > put in an LF351 and bingo....it was fixed! Or so I thought > basically > > I did it again once after playing around with it after an > hour..now > > normally it did it every 30 seconds so it is 99% better and hasn't > > done it again. > > > > Maybe the DAC is faulty itself but I still don't understand how > this > > would effect the displayed pot values. Surely that's down to the > A/D? > > > > Also with good news comes bad...after fixing that problem I > rechecked > > the voices..I had lost another voice! AFter finding another red > hot > > regulator on a voice board I found all three CEM3340's were > shorted!! > > Arggh!! I was feeling pretty sick considering how expensive they > are! > > > > I must have shorted something out while trying to fix the pot > > problem...oh well.. > > > > So anyway I've got 5 CEM3340's on the way(one spare), a 3310 and a > > 3360. After calibration that should be it. Fingers crossed X > > > > > > --- In vintagesynthrepair@ yahoogroups. com, "eggwheatis" > > <eggwheatis@ > wrote: > > > > > > Well this (hopefully)last problem is proving to be really > difficult > > > to solve. It wasnt the Zener even though it was bad. It acts as > a > > > regulator for the +10 vdc to the DAC from the Control boards... > It > > > was causing it to sit at 11.5 vdc. Changing it did nothing. > > > > > > It's one of those niggling annoying problems that seems to be > > > undetectable. ..its driving me nuts..I'll try to explain it > better. > > > > > > Basically you turn a pot on this synth and the pots value is > shown > > on > > > the alpha/dec LED display, you turn the second pot the display > > > instantly shows that pots value..so far so good...but after a > few > > > turns of various pots, it will stick on a value and won't change > > with > > > the new pot movements, pressing buttons, turning other pots wont > > get > > > rid of it(you can see the correct values flickering behind > > it)..even > > > turning it on and off. You have to go back and find the pot > thats > > got > > > the value 'stuck'. Zero that pot and it's fine again. It's > totally > > > random and depends on the combination of pots and values. The > > actual > > > sound itself changes fine with the pot movement. It's just the > > > displaying of the values that is a bit screwed. > > > > > > Remember is the physical displaying of the values that gets > stuck, > > > not the actual values that control the analogue parameters. They > > are > > > working fine. > > > > > > If anyone can help I'd really appreciate it, the schems are > here: > > > http://www.matrixsy nth.com/blog/ media/Moog/ MemorymoogSchema tics/ > > > > > > The service manual is here: > > > http://www.retrosyn th.com/docs/ memorymoog/ mm_service. pdf > > > > > > Apart from this fault..it seems to be almost fixed. > > > > > > Thanks, Phil. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > --- In vintagesynthrepair@ yahoogroups. com, "eggwheatis" > > > <eggwheatis@ > wrote: > > > > > > > > A bit more fixed..:o) > > > > > > > > well actually diagnosed.. > > > > > > > > The reason all the voices were dead on one card was because a > > > > CEM3340 VCO chip was shorted, this pulled down the 7905 > regulator > > > > that sits on the edge of each voice card killing the supply to > > the > > > > other CEM's. I found that a CEM3360 VCA chip was also dead on > the > > > > same card. So after swapping a few CEM's around I know have > just > > > one > > > > Oscillator 3 down. > > > > > > > > After that I noticed the VCF adsr wasnt working on one voice. > A > > > > quick look at the schems revealed it is generated by a CEM3310 > on > > > > the contour generator board. Sure enough I found the 3310 was > > dead. > > > > > > > > So that, on the face of it, appears to be the voices sorted > out. > > Im > > > > sure I'll find more problems. > > > > > > > > The synth is still totally out of tune, so it will need full > > > > calibration. I'm not going to try that until I have located > all > > the > > > > CEM chips I need. > > > > > > > > I also swapped all the HC ic's out for the correct LS versions > > and > > > > anything that isnt specified in the parts list. For instance a > > lot > > > > of the op amps are 1458's, the schematics and parts list > specify > > > > 4558. The manual also has an addition saying you should swap > any > > > > found to 4558. The 4558 is apparently superior. > > > > > > > > I still have the problem with the displayed pot values, I > talked > > > > about in an earlier post(below). It drove me mad..I checked > out > > the > > > > whole of the POTPOS circuit, the MUX circuit..the display > > > > circuits.... eventually after forgetting theory, schematics and > > just > > > > randomly testing things, I found CR1 to be open on the DMUX > > board! > > > > It's a 6.2 Zener..I avent changed it yet as I was going > out..but > > > > after checking the schems I reckon I might have solved > it..it's > > not > > > > mentioned in the service manual, and it's right on the edge of > > the > > > > schems.. > > > > > > > > Thats it for now..Phil. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > --- In vintagesynthrepair@ yahoogroups. com, "eggwheatis" > > > > <eggwheatis@ > wrote: > > > > > > > > > > Fixed the hopeless switch matrix :o) there was a ribbon > cable > > > > plugged > > > > > in the wrong way round into the common analogue board! Large > > > > repairer > > > > > error #5..... > > > > > > > > > > So now all the button functions work properly and I have > > > > Oscillator 3 > > > > > back!... although only 4 voices working. > > > > > > > > > > I also changed 4 of the hc138's to LS138's and the filter > has > > now > > > > > started tracking the keyboard properly...I discovered two > > HC377's > > > > on > > > > > the digital board too..they should be LS variants again... > > > > > > > > > > So basically im left with OSC 1,2 and 3 not working on the > same > > > > voice > > > > > card(3 dead cem3340's on the same card surely not? I hope) > OSC > > 3 > > > > dead > > > > > on one other card. Hopeless autotune '0 tuned' all out of > tune > > > > with > > > > > each other even on the same cards... > > > > > > > > > > Oh and the weird pot problem: when you > > > > > move the pots the numbers in the alpha display move up and > down > > > > which > > > > > is correct, however say you turn one pot and move to > another, > > > > > well the first pots status doesn't clear from the display, > it's > > > > > stuck there, you can see it flicker as you move the other > pot > > but > > > > > it's stuck there unless you go back and zero the original > pot. > > > > Only > > > > > a few pots seem toà cause this problem. > > > > > > > > > > I reckon swapping out those wrong HC ic's will cure > > that..maybe. . > > > > > > > > > > Im sure I'll find more problems too. It's amazing > how 'previous > > > > > repairer error' can completely disable a synth that probably > > only > > > > had > > > > > a couple of faults to start with. > > > > > > > > > > Getting there... > > > > > > > > > > > > > > > > > > > > --- In vintagesynthrepair@ yahoogroups. com, "eggwheatis" > > > > > <eggwheatis@ > wrote: > > > > > > > > > > > > Well ive now got sound out of it :o) this is going to be > fun > > > > > > though...yet again someones been in this before me that > looks > > > > like > > > > > > they weren't on the ball. All the IC are in sockets...but > > most > > > > of > > > > > > them have been replaced sometimes with the wrong variant. > > > > > > > > > > > > No sound was indeed caused by the PSU....an electrolytic > > > > capacitor > > > > > in > > > > > > the +15 circuit on the DMUX board was put in backwards. > > > Repairer > > > > > > error #1. > > > > > > > > > > > > I thought I'd start by fixing the LED's on the left hand > > control > > > > > (LHC) > > > > > > board and the missing digit in the alpha display so I > could > > see > > > > > what > > > > > > was going on better... > > > > > > > > > > > > The dead/stuck on LED's were caused by one of the legs of > the > > > > ls378 > > > > > > at U8 on the LHC board being bent under itself in the > socket. > > > > > > Repairer error #2. > > > > > > > > > > > > The dead digit in the alpha display was caused by a dead > > output > > > > on > > > > > > the LS273 at U1 on the LHC board. > > > > > > > > > > > > Anyway so now I can see and hear whats going on I have a > > whole > > > > host > > > > > > of new problems :o) > > > > > > > > > > > > I have no Oscillator 3 at all across the board, Osc 1 and > 2 > > > also > > > > > dont > > > > > > work on one voice. None of the oscillators will auto- tune, > i > > > get > > > > > > the '0 tuned message'. The filter self oscillates but wont > > > track > > > > > the > > > > > > keyboard. > > > > > > > > > > > > The switch matrix is hopeless on the LHC board, buttons > > > activate > > > > > > wrong functions basically, the appegiator doesnt work nor > > does > > > > the > > > > > > hold function... > > > > > > > > > > > > Things I can see right off the bat but need to get spares > to > > > fix > > > > > are: > > > > > > All the 74ls138's on the digital board have been replaced > > with > > > > HC > > > > > > Cmos variants...not a good idea, these are not compatible > > with > > > > TTL > > > > > in > > > > > > most cases, so i would think they are causing a lot of > > problems > > > > > > (fingers crossed). You need LS in there or HCT at least.. > > > > Repairer > > > > > > Error #3 > > > > > > > > > > > > Also there is a TL071 missing out of a socket on the DMUX > > > > > board..this > > > > > > is connected to the auto tune circuit..buffers one of the > > > > outputs I > > > > > > think. Repairer Error #4 > > > > > > > > > > > > All in all a lot of fun! > > > > > > > > > > > > Phil. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > --- In vintagesynthrepair@ yahoogroups. com, Philip > > <eggwheatis@ > > > > > > > wrote: > > > > > > > > > > > > > > I just gotàa broken Memorymoog. It's really clean, near > > mint > > > > in > > > > > > fact, but not working. Half the reason I bought it is > because > > I > > > > > like > > > > > > a challenge :o) ..I haven't even opened it up yet so I > > thought > > > > I'd > > > > > > post up the problems to see if anyone has an idea. > > > > > > > à> > > > > > > It boots up ok, but makes very little sound the most you > > get > > > > out > > > > > of > > > > > > it is a thump or slight squeak when you hit a key, the > same > > > > pitch > > > > > > wherever you hit. The digital side seem to be mostly > working. > > > > > > > à> > > > > > > If you hit autotune it comes back with '0 tuned' so it > > can't > > > > tune > > > > > > any of the oscillators probably because it cant 'hear' > them > > so > > > > to > > > > > > speak. > > > > > > > à> > > > > > > First thoughts are some kind of DAC problem. > > > > > > > à> > > > > > > 2: All the LED's on the left hand side don't work at all > > but > > > > the > > > > > > buttons do. A few are just stuck on all the time, again > the > > > > buttons > > > > > > work. > > > > > > > à> > > > > > > 3: one digit on the alpha/numeric display is barely > visible. > > > > > > > à> > > > > > > 4: this is a slightly weird one which is hard to > describe, > > > > when > > > > > you > > > > > > move the pots the numbers in the alpha display move up and > > down > > > > > which > > > > > > is correct., however say you turn oneàpot and move to > > another, > > > > > > wellàthe first pots status doesn't clear from the > display, > > > it's > > > > > > stuck there, you can see it flicker as you move the other > pot > > > > but > > > > > > it's stuck there unless you go back and zero theàoriginal > > pot. > > > > > Only > > > > > > a few pots seem toàcause this problem. > > > > > > > à> > > > > > > Any ideas would be helpful. Obviously the first thing im
> > > going > > > > to > > > > > > check is the PSU when I open it up later. > > > > > > > ÃÂ > > > > > > > Thanks, Phil. > > > > > > > ÃÂ > > > > > > > > > > > > > > Send instant messages to your online friends > > > > > > http://uk.messenger .yahoo.com > > > > > > > > > > > > > > > > > > > > > > > > > > > >
2008-11-02 by Philip
Hiya....the display reads 77 after inputting C0... Thanks for the advice...the voices were hopelessly out of tune...but after messing around for 4 hours haha..I got them all in tune so now I have '6 tuned'. I also balanced up the VCA's.... So now ive shown up what I think must be more problems with the filters or filter control; The filters sound ok on all six voice cards..they could do with a fine tune to match them up..but not too bad. The problem is when you go into MONO mode, the filter stops tracking across the keyboard. The 1/3 and 2/3 KB Tracking buttons in the filter section have no effect. It's tracks ok in polyphonic mode. Also in Poly mode switching the 2/3 KB Tracking button on in the filter section makes the third oscillator drop almost one octave across all 6 voices. So what do you reckon? Thanks< phil. --- On Sat, 1/11/08, gerryrdahl <gerryrdahl@...> wrote: From: gerryrdahl <gerryrdahl@...> Subject: [vintagesynthrepair] Re: Memorymoog repair To: vintagesynthrepair@yahoogroups.com Date: Saturday, 1 November, 2008, 12:50 PM Hi Phil, What are the readouts for the Osc's? When you press c-7-enter-enter- 1-1, what does the display read? If it reads dead osc or LOW, check the others and see what you get. You may have a CTC osc scanning problem, where the CTC cannot count (or check the tuning) on the osc's. Also what version firmware do you have? When you do a c-0-enter all the leds blink, in the patch readout will be a flashing number, this is the version. Also check the pitch bend and fine tune circuit. These are supposed to be disabled during autotune. if not then the MM will not tune. Let us know. GD --- In vintagesynthrepair@ yahoogroups. com, Philip <eggwheatis@ ...> wrote: > > Hi, i just started back tonight on it.... After a a very expensive purchase of some CEM ic's I have all the voices working on it now. >  > I was seriously scared off putting the new IC's in in case they died again...but I bit the bullet and all seems fine. Phew! >  > SO now I have a fully working but seriously out of tune Memorymoog. The autotune wont tune it..too far out. I just get '0 tuned' >  > I checked the calibration out in the manual and I found it a bit confusing... >  > Has anyone got any tips on calibrating it? >  > Thanks, Phil. >  > > > --- On Tue, 21/10/08, gerryrdahl <gerryrdahl@ ...> wrote: > > From: gerryrdahl <gerryrdahl@ ...> > Subject: [vintagesynthrepair ] Re: Memorymoog repair > To: vintagesynthrepair@ yahoogroups. com > Date: Tuesday, 21 October, 2008, 4:13 AM > > > > > > > Hi Phil, > How has the Memorymoog turned out? > > Did the replacement CEM's and a calibration finish her up? > > Would like to know. > > Thanks. > GD > > --- In vintagesynthrepair@ yahoogroups. com, "eggwheatis" > <eggwheatis@ ...> wrote: > > > > Phew..I fixed the pot problem, well I think I have. > > > > I ended up taking every board out and going through them with a > fine > > toothed comb, I cleaned any surplus flux off, checked > > everything.. scoped everything. I just could not find it. > > > > Then something occured to me..like many things do when repairing > > stuff!..on the schematics there is an LF351 op-amp on the output > of > > the DAC..but it the actual socket was a TL071 which should be > fine, > > and i had already swapped it out..anyway it is an equivalent and > is > > even mentioned in parenthesis on the parts sheet next to LF351, as > is > > TL072 as an equivalent for LF353. In fact my memorymoog has > TL072'a > > and TL)71's throughout. > > > > Now I know how sensitive digital circuits are to 'equivalents' so > I > > put in an LF351 and bingo....it was fixed! Or so I thought > basically > > I did it again once after playing around with it after an > hour..now > > normally it did it every 30 seconds so it is 99% better and hasn't > > done it again. > > > > Maybe the DAC is faulty itself but I still don't understand how > this > > would effect the displayed pot values. Surely that's down to the > A/D? > > > > Also with good news comes bad...after fixing that problem I > rechecked > > the voices..I had lost another voice! AFter finding another red > hot > > regulator on a voice board I found all three CEM3340's were > shorted!! > > Arggh!! I was feeling pretty sick considering how expensive they > are! > > > > I must have shorted something out while trying to fix the pot > > problem...oh well.. > > > > So anyway I've got 5 CEM3340's on the way(one spare), a 3310 and a > > 3360. After calibration that should be it. Fingers crossed X > > > > > > --- In vintagesynthrepair@ yahoogroups. com, "eggwheatis" > > <eggwheatis@ > wrote: > > > > > > Well this (hopefully)last problem is proving to be really > difficult > > > to solve. It wasnt the Zener even though it was bad. It acts as > a > > > regulator for the +10 vdc to the DAC from the Control boards... > It > > > was causing it to sit at 11.5 vdc. Changing it did nothing. > > > > > > It's one of those niggling annoying problems that seems to be > > > undetectable. ..its driving me nuts..I'll try to explain it > better. > > > > > > Basically you turn a pot on this synth and the pots value is > shown > > on > > > the alpha/dec LED display, you turn the second pot the display > > > instantly shows that pots value..so far so good...but after a > few > > > turns of various pots, it will stick on a value and won't change > > with > > > the new pot movements, pressing buttons, turning other pots wont > > get > > > rid of it(you can see the correct values flickering behind > > it)..even > > > turning it on and off. You have to go back and find the pot > thats > > got > > > the value 'stuck'. Zero that pot and it's fine again. It's > totally > > > random and depends on the combination of pots and values. The > > actual > > > sound itself changes fine with the pot movement. It's just the > > > displaying of the values that is a bit screwed. > > > > > > Remember is the physical displaying of the values that gets > stuck, > > > not the actual values that control the analogue parameters. They > > are > > > working fine. > > > > > > If anyone can help I'd really appreciate it, the schems are > here: > > > http://www.matrixsy nth.com/blog/ media/Moog/ MemorymoogSchema tics/ > > > > > > The service manual is here: > > > http://www.retrosyn th.com/docs/ memorymoog/ mm_service. pdf > > > > > > Apart from this fault..it seems to be almost fixed. > > > > > > Thanks, Phil. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > --- In vintagesynthrepair@ yahoogroups. com, "eggwheatis" > > > <eggwheatis@ > wrote: > > > > > > > > A bit more fixed..:o) > > > > > > > > well actually diagnosed.. > > > > > > > > The reason all the voices were dead on one card was because a > > > > CEM3340 VCO chip was shorted, this pulled down the 7905 > regulator > > > > that sits on the edge of each voice card killing the supply to > > the > > > > other CEM's. I found that a CEM3360 VCA chip was also dead on > the > > > > same card. So after swapping a few CEM's around I know have > just > > > one > > > > Oscillator 3 down. > > > > > > > > After that I noticed the VCF adsr wasnt working on one voice. > A > > > > quick look at the schems revealed it is generated by a CEM3310 > on > > > > the contour generator board. Sure enough I found the 3310 was > > dead. > > > > > > > > So that, on the face of it, appears to be the voices sorted > out. > > Im > > > > sure I'll find more problems. > > > > > > > > The synth is still totally out of tune, so it will need full > > > > calibration. I'm not going to try that until I have located > all > > the > > > > CEM chips I need. > > > > > > > > I also swapped all the HC ic's out for the correct LS versions > > and > > > > anything that isnt specified in the parts list. For instance a > > lot > > > > of the op amps are 1458's, the schematics and parts list > specify > > > > 4558. The manual also has an addition saying you should swap > any > > > > found to 4558. The 4558 is apparently superior. > > > > > > > > I still have the problem with the displayed pot values, I > talked > > > > about in an earlier post(below). It drove me mad..I checked > out > > the > > > > whole of the POTPOS circuit, the MUX circuit..the display > > > > circuits.... eventually after forgetting theory, schematics and > > just > > > > randomly testing things, I found CR1 to be open on the DMUX > > board! > > > > It's a 6.2 Zener..I avent changed it yet as I was going > out..but > > > > after checking the schems I reckon I might have solved > it..it's > > not > > > > mentioned in the service manual, and it's right on the edge of > > the > > > > schems.. > > > > > > > > Thats it for now..Phil. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > --- In vintagesynthrepair@ yahoogroups. com, "eggwheatis" > > > > <eggwheatis@ > wrote: > > > > > > > > > > Fixed the hopeless switch matrix :o) there was a ribbon > cable > > > > plugged > > > > > in the wrong way round into the common analogue board! Large > > > > repairer > > > > > error #5..... > > > > > > > > > > So now all the button functions work properly and I have > > > > Oscillator 3 > > > > > back!... although only 4 voices working. > > > > > > > > > > I also changed 4 of the hc138's to LS138's and the filter > has > > now > > > > > started tracking the keyboard properly...I discovered two > > HC377's > > > > on > > > > > the digital board too..they should be LS variants again... > > > > > > > > > > So basically im left with OSC 1,2 and 3 not working on the > same > > > > voice > > > > > card(3 dead cem3340's on the same card surely not? I hope) > OSC > > 3 > > > > dead > > > > > on one other card. Hopeless autotune '0 tuned' all out of > tune > > > > with > > > > > each other even on the same cards... > > > > > > > > > > Oh and the weird pot problem: when you > > > > > move the pots the numbers in the alpha display move up and > down > > > > which > > > > > is correct, however say you turn one pot and move to > another, > > > > > well the first pots status doesn't clear from the display, > it's > > > > > stuck there, you can see it flicker as you move the other > pot > > but > > > > > it's stuck there unless you go back and zero the original > pot. > > > > Only > > > > > a few pots seem to cause this problem. > > > > > > > > > > I reckon swapping out those wrong HC ic's will cure > > that..maybe. . > > > > > > > > > > Im sure I'll find more problems too. It's amazing > how 'previous > > > > > repairer error' can completely disable a synth that probably > > only > > > > had > > > > > a couple of faults to start with. > > > > > > > > > > Getting there... > > > > > > > > > > > > > > > > > > > > --- In vintagesynthrepair@ yahoogroups. com, "eggwheatis" > > > > > <eggwheatis@ > wrote: > > > > > > > > > > > > Well ive now got sound out of it :o) this is going to be > fun > > > > > > though...yet again someones been in this before me that > looks > > > > like > > > > > > they weren't on the ball. All the IC are in sockets...but > > most > > > > of > > > > > > them have been replaced sometimes with the wrong variant. > > > > > > > > > > > > No sound was indeed caused by the PSU....an electrolytic > > > > capacitor > > > > > in > > > > > > the +15 circuit on the DMUX board was put in backwards. > > > Repairer > > > > > > error #1. > > > > > > > > > > > > I thought I'd start by fixing the LED's on the left hand > > control > > > > > (LHC) > > > > > > board and the missing digit in the alpha display so I > could > > see > > > > > what > > > > > > was going on better... > > > > > > > > > > > > The dead/stuck on LED's were caused by one of the legs of > the > > > > ls378 > > > > > > at U8 on the LHC board being bent under itself in the > socket. > > > > > > Repairer error #2. > > > > > > > > > > > > The dead digit in the alpha display was caused by a dead > > output > > > > on > > > > > > the LS273 at U1 on the LHC board. > > > > > > > > > > > > Anyway so now I can see and hear whats going on I have a > > whole > > > > host > > > > > > of new problems :o) > > > > > > > > > > > > I have no Oscillator 3 at all across the board, Osc 1 and > 2 > > > also > > > > > dont > > > > > > work on one voice. None of the oscillators will auto- tune, > i > > > get > > > > > > the '0 tuned message'. The filter self oscillates but wont > > > track > > > > > the > > > > > > keyboard. > > > > > > > > > > > > The switch matrix is hopeless on the LHC board, buttons > > > activate > > > > > > wrong functions basically, the appegiator doesnt work nor > > does > > > > the > > > > > > hold function... > > > > > > > > > > > > Things I can see right off the bat but need to get spares > to > > > fix > > > > > are: > > > > > > All the 74ls138's on the digital board have been replaced > > with > > > > HC > > > > > > Cmos variants...not a good idea, these are not compatible > > with > > > > TTL > > > > > in > > > > > > most cases, so i would think they are causing a lot of > > problems > > > > > > (fingers crossed). You need LS in there or HCT at least.. > > > > Repairer > > > > > > Error #3 > > > > > > > > > > > > Also there is a TL071 missing out of a socket on the DMUX > > > > > board..this > > > > > > is connected to the auto tune circuit..buffers one of the > > > > outputs I > > > > > > think. Repairer Error #4 > > > > > > > > > > > > All in all a lot of fun! > > > > > > > > > > > > Phil. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > --- In vintagesynthrepair@ yahoogroups. com, Philip > > <eggwheatis@ > > > > > > > wrote: > > > > > > > > > > > > > > I just got a broken Memorymoog. It's really clean, near > > mint > > > > in > > > > > > fact, but not working. Half the reason I bought it is > because > > I > > > > > like > > > > > > a challenge :o) ..I haven't even opened it up yet so I > > thought > > > > I'd > > > > > > post up the problems to see if anyone has an idea. > > > > > > >  > > > > > > > It boots up ok, but makes very little sound the most you > > get > > > > out > > > > > of > > > > > > it is a thump or slight squeak when you hit a key, the > same > > > > pitch > > > > > > wherever you hit. The digital side seem to be mostly > working. > > > > > > >  > > > > > > > If you hit autotune it comes back with '0 tuned' so it > > can't > > > > tune > > > > > > any of the oscillators probably because it cant 'hear' > them > > so > > > > to > > > > > > speak. > > > > > > >  > > > > > > > First thoughts are some kind of DAC problem. > > > > > > >  > > > > > > > 2: All the LED's on the left hand side don't work at all > > but > > > > the > > > > > > buttons do. A few are just stuck on all the time, again > the > > > > buttons > > > > > > work. > > > > > > >  > > > > > > > 3: one digit on the alpha/numeric display is barely > visible. > > > > > > >  > > > > > > > 4: this is a slightly weird one which is hard to > describe, > > > > when > > > > > you > > > > > > move the pots the numbers in the alpha display move up and > > down > > > > > which > > > > > > is correct., however say you turn one pot and move to > > another, > > > > > > well the first pots status doesn't clear from the > display, > > > it's > > > > > > stuck there, you can see it flicker as you move the other > pot > > > > but > > > > > > it's stuck there unless you go back and zero the original > > pot. > > > > > Only > > > > > > a few pots seem to cause this problem. > > > > > > >  > > > > > > > Any ideas would be helpful. Obviously the first thing im
> > > going > > > > to > > > > > > check is the PSU when I open it up later. > > > > > > >  > > > > > > > Thanks, Phil. > > > > > > >  > > > > > > > > > > > > > > Send instant messages to your online friends > > > > > > http://uk.messenger .yahoo.com > > > > > > > > > > > > > > > > > > > > > > > > > > > >
2008-11-03 by eggwheatis
--- In vintagesynthrepair@yahoogroups.com, Philip <eggwheatis@...> wrote: I found it. Connector P28 was plugged in backwards on the Common Analogue board. :o) Dare I say it's almost 100% fixed?? Just got to tune the filters tomorrow! Thanks, Phil. > The problem is when you go into MONO mode, the filter stops tracking across the keyboard. The 1/3 and 2/3 KB Tracking buttons in the filter section have no effect. It's tracks ok in polyphonic mode. >  > Also in Poly mode switching the 2/3 KB Tracking button on in the filter section makes the third oscillator drop almost one octave across all 6 voices. > > So what do you reckon? > > Thanks< phil. > > >  >  >  > > > --- On Sat, 1/11/08, gerryrdahl <gerryrdahl@...> wrote: > > From: gerryrdahl <gerryrdahl@...> > Subject: [vintagesynthrepair] Re: Memorymoog repair > To: vintagesynthrepair@yahoogroups.com > Date: Saturday, 1 November, 2008, 12:50 PM > > > > > > > Hi Phil, > What are the readouts for the Osc's? > When you press c-7-enter-enter- 1-1, what does the display read? > If it reads dead osc or LOW, check the others and see what > you get. > You may have a CTC osc scanning problem, where the CTC cannot > count (or check the tuning) on the osc's. > > Also what version firmware do you have? > When you do a c-0-enter all the leds blink, in the patch readout > will be a flashing number, this is the version. > > Also check the pitch bend and fine tune circuit. > These are supposed to be disabled during autotune. if not > then the MM will not tune. > > Let us know. > GD > > --- In vintagesynthrepair@ yahoogroups. com, Philip <eggwheatis@ ...> > wrote: > > > > Hi, i just started back tonight on it.... After a a very expensive > purchase ofàsome CEM ic's I have all the voices working on it now. > > à> > I was seriously scared off putting the new IC's in in case they > died again...but I bit the bullet and all seems fine. Phew! > > à> > SO now I have a fully working but seriously out of tune > Memorymoog. The autotune wont tuneàit..too far out. I just get '0 > tuned' > > à> > I checked the calibration out in the manual and I found it a bit > confusing... > > à> > Has anyone got any tips on calibrating it? > > à> > Thanks, Phil. > > à> > > > > > --- On Tue, 21/10/08, gerryrdahl <gerryrdahl@ ...> wrote: > > > > From: gerryrdahl <gerryrdahl@ ...> > > Subject: [vintagesynthrepair ] Re: Memorymoog repair > > To: vintagesynthrepair@ yahoogroups. com > > Date: Tuesday, 21 October, 2008, 4:13 AM > > > > > > > > > > > > > > Hi Phil, > > How has the Memorymoog turned out? > > > > Did the replacement CEM's and a calibration finish her up? > > > > Would like to know. > > > > Thanks. > > GD > > > > --- In vintagesynthrepair@ yahoogroups. com, "eggwheatis" > > <eggwheatis@ ...> wrote: > > > > > > Phew..I fixed the pot problem, well I think I have. > > > > > > I ended up taking every board out and going through them with a > > fine > > > toothed comb, I cleaned any surplus flux off, checked > > > everything.. scoped everything. I just could not find it. > > > > > > Then something occured to me..like many things do when repairing > > > stuff!..on the schematics there is an LF351 op-amp on the output > > of > > > the DAC..but it the actual socket was a TL071 which should be > > fine, > > > and i had already swapped it out..anyway it is an equivalent and > > is > > > even mentioned in parenthesis on the parts sheet next to LF351, > as > > is > > > TL072 as an equivalent for LF353. In fact my memorymoog has > > TL072'a > > > and TL)71's throughout. > > > > > > Now I know how sensitive digital circuits are to 'equivalents' > so > > I > > > put in an LF351 and bingo....it was fixed! Or so I thought > > basically > > > I did it again once after playing around with it after an > > hour..now > > > normally it did it every 30 seconds so it is 99% better and > hasn't > > > done it again. > > > > > > Maybe the DAC is faulty itself but I still don't understand how > > this > > > would effect the displayed pot values. Surely that's down to the > > A/D? > > > > > > Also with good news comes bad...after fixing that problem I > > rechecked > > > the voices..I had lost another voice! AFter finding another red > > hot > > > regulator on a voice board I found all three CEM3340's were > > shorted!! > > > Arggh!! I was feeling pretty sick considering how expensive they > > are! > > > > > > I must have shorted something out while trying to fix the pot > > > problem...oh well.. > > > > > > So anyway I've got 5 CEM3340's on the way(one spare), a 3310 and > a > > > 3360. After calibration that should be it. Fingers crossed X > > > > > > > > > --- In vintagesynthrepair@ yahoogroups. com, "eggwheatis" > > > <eggwheatis@ > wrote: > > > > > > > > Well this (hopefully)last problem is proving to be really > > difficult > > > > to solve. It wasnt the Zener even though it was bad. It acts > as > > a > > > > regulator for the +10 vdc to the DAC from the Control > boards... > > It > > > > was causing it to sit at 11.5 vdc. Changing it did nothing. > > > > > > > > It's one of those niggling annoying problems that seems to be > > > > undetectable. ..its driving me nuts..I'll try to explain it > > better. > > > > > > > > Basically you turn a pot on this synth and the pots value is > > shown > > > on > > > > the alpha/dec LED display, you turn the second pot the display > > > > instantly shows that pots value..so far so good...but after a > > few > > > > turns of various pots, it will stick on a value and won't > change > > > with > > > > the new pot movements, pressing buttons, turning other pots > wont > > > get > > > > rid of it(you can see the correct values flickering behind > > > it)..even > > > > turning it on and off. You have to go back and find the pot > > thats > > > got > > > > the value 'stuck'. Zero that pot and it's fine again. It's > > totally > > > > random and depends on the combination of pots and values. The > > > actual > > > > sound itself changes fine with the pot movement. It's just the > > > > displaying of the values that is a bit screwed. > > > > > > > > Remember is the physical displaying of the values that gets > > stuck, > > > > not the actual values that control the analogue parameters. > They > > > are > > > > working fine. > > > > > > > > If anyone can help I'd really appreciate it, the schems are > > here: > > > > http://www.matrixsy nth.com/blog/ media/Moog/ MemorymoogSchema > tics/ > > > > > > > > The service manual is here: > > > > http://www.retrosyn th.com/docs/ memorymoog/ mm_service. pdf > > > > > > > > Apart from this fault..it seems to be almost fixed. > > > > > > > > Thanks, Phil. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > --- In vintagesynthrepair@ yahoogroups. com, "eggwheatis" > > > > <eggwheatis@ > wrote: > > > > > > > > > > A bit more fixed..:o) > > > > > > > > > > well actually diagnosed.. > > > > > > > > > > The reason all the voices were dead on one card was because > a > > > > > CEM3340 VCO chip was shorted, this pulled down the 7905 > > regulator > > > > > that sits on the edge of each voice card killing the supply > to > > > the > > > > > other CEM's. I found that a CEM3360 VCA chip was also dead > on > > the > > > > > same card. So after swapping a few CEM's around I know have > > just > > > > one > > > > > Oscillator 3 down. > > > > > > > > > > After that I noticed the VCF adsr wasnt working on one > voice. > > A > > > > > quick look at the schems revealed it is generated by a > CEM3310 > > on > > > > > the contour generator board. Sure enough I found the 3310 > was > > > dead. > > > > > > > > > > So that, on the face of it, appears to be the voices sorted > > out. > > > Im > > > > > sure I'll find more problems. > > > > > > > > > > The synth is still totally out of tune, so it will need full > > > > > calibration. I'm not going to try that until I have located > > all > > > the > > > > > CEM chips I need. > > > > > > > > > > I also swapped all the HC ic's out for the correct LS > versions > > > and > > > > > anything that isnt specified in the parts list. For instance > a > > > lot > > > > > of the op amps are 1458's, the schematics and parts list > > specify > > > > > 4558. The manual also has an addition saying you should swap > > any > > > > > found to 4558. The 4558 is apparently superior. > > > > > > > > > > I still have the problem with the displayed pot values, I > > talked > > > > > about in an earlier post(below). It drove me mad..I checked > > out > > > the > > > > > whole of the POTPOS circuit, the MUX circuit..the display > > > > > circuits.... eventually after forgetting theory, schematics > and > > > just > > > > > randomly testing things, I found CR1 to be open on the DMUX > > > board! > > > > > It's a 6.2 Zener..I avent changed it yet as I was going > > out..but > > > > > after checking the schems I reckon I might have solved > > it..it's > > > not > > > > > mentioned in the service manual, and it's right on the edge > of > > > the > > > > > schems.. > > > > > > > > > > Thats it for now..Phil. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > --- In vintagesynthrepair@ yahoogroups. com, "eggwheatis" > > > > > <eggwheatis@ > wrote: > > > > > > > > > > > > Fixed the hopeless switch matrix :o) there was a ribbon > > cable > > > > > plugged > > > > > > in the wrong way round into the common analogue board! > Large > > > > > repairer > > > > > > error #5..... > > > > > > > > > > > > So now all the button functions work properly and I have > > > > > Oscillator 3 > > > > > > back!... although only 4 voices working. > > > > > > > > > > > > I also changed 4 of the hc138's to LS138's and the filter > > has > > > now > > > > > > started tracking the keyboard properly...I discovered two > > > HC377's > > > > > on > > > > > > the digital board too..they should be LS variants again... > > > > > > > > > > > > So basically im left with OSC 1,2 and 3 not working on the > > same > > > > > voice > > > > > > card(3 dead cem3340's on the same card surely not? I hope) > > OSC > > > 3 > > > > > dead > > > > > > on one other card. Hopeless autotune '0 tuned' all out of > > tune > > > > > with > > > > > > each other even on the same cards... > > > > > > > > > > > > Oh and the weird pot problem: when you > > > > > > move the pots the numbers in the alpha display move up and > > down > > > > > which > > > > > > is correct, however say you turn one pot and move to > > another, > > > > > > well the first pots status doesn't clear from the display, > > it's > > > > > > stuck there, you can see it flicker as you move the other > > pot > > > but > > > > > > it's stuck there unless you go back and zero the original > > pot. > > > > > Only > > > > > > a few pots seem toÃâ cause this problem. > > > > > > > > > > > > I reckon swapping out those wrong HC ic's will cure > > > that..maybe. . > > > > > > > > > > > > Im sure I'll find more problems too. It's amazing > > how 'previous > > > > > > repairer error' can completely disable a synth that > probably > > > only > > > > > had > > > > > > a couple of faults to start with. > > > > > > > > > > > > Getting there... > > > > > > > > > > > > > > > > > > > > > > > > --- In vintagesynthrepair@ yahoogroups. com, "eggwheatis" > > > > > > <eggwheatis@ > wrote: > > > > > > > > > > > > > > Well ive now got sound out of it :o) this is going to be > > fun > > > > > > > though...yet again someones been in this before me that > > looks > > > > > like > > > > > > > they weren't on the ball. All the IC are in > sockets...but > > > most > > > > > of > > > > > > > them have been replaced sometimes with the wrong variant. > > > > > > > > > > > > > > No sound was indeed caused by the PSU....an electrolytic > > > > > capacitor > > > > > > in > > > > > > > the +15 circuit on the DMUX board was put in backwards. > > > > Repairer > > > > > > > error #1. > > > > > > > > > > > > > > I thought I'd start by fixing the LED's on the left hand > > > control > > > > > > (LHC) > > > > > > > board and the missing digit in the alpha display so I > > could > > > see > > > > > > what > > > > > > > was going on better... > > > > > > > > > > > > > > The dead/stuck on LED's were caused by one of the legs > of > > the > > > > > ls378 > > > > > > > at U8 on the LHC board being bent under itself in the > > socket. > > > > > > > Repairer error #2. > > > > > > > > > > > > > > The dead digit in the alpha display was caused by a dead > > > output > > > > > on > > > > > > > the LS273 at U1 on the LHC board. > > > > > > > > > > > > > > Anyway so now I can see and hear whats going on I have a > > > whole > > > > > host > > > > > > > of new problems :o) > > > > > > > > > > > > > > I have no Oscillator 3 at all across the board, Osc 1 > and > > 2 > > > > also > > > > > > dont > > > > > > > work on one voice. None of the oscillators will auto- > tune, > > i > > > > get > > > > > > > the '0 tuned message'. The filter self oscillates but > wont > > > > track > > > > > > the > > > > > > > keyboard. > > > > > > > > > > > > > > The switch matrix is hopeless on the LHC board, buttons > > > > activate > > > > > > > wrong functions basically, the appegiator doesnt work > nor > > > does > > > > > the > > > > > > > hold function... > > > > > > > > > > > > > > Things I can see right off the bat but need to get > spares > > to > > > > fix > > > > > > are: > > > > > > > All the 74ls138's on the digital board have been > replaced > > > with > > > > > HC > > > > > > > Cmos variants...not a good idea, these are not > compatible > > > with > > > > > TTL > > > > > > in > > > > > > > most cases, so i would think they are causing a lot of > > > problems > > > > > > > (fingers crossed). You need LS in there or HCT at > least.. > > > > > Repairer > > > > > > > Error #3 > > > > > > > > > > > > > > Also there is a TL071 missing out of a socket on the > DMUX > > > > > > board..this > > > > > > > is connected to the auto tune circuit..buffers one of > the > > > > > outputs I > > > > > > > think. Repairer Error #4 > > > > > > > > > > > > > > All in all a lot of fun! > > > > > > > > > > > > > > Phil. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > --- In vintagesynthrepair@ yahoogroups. com, Philip > > > <eggwheatis@ > > > > > > > > wrote: > > > > > > > > > > > > > > > > I just gotÃâàa broken Memorymoog. It's really clean, > near > > > mint > > > > > in > > > > > > > fact, but not working. Half the reason I bought it is > > because > > > I > > > > > > like > > > > > > > a challenge :o) ..I haven't even opened it up yet so I > > > thought > > > > > I'd > > > > > > > post up the problems to see if anyone has an idea. > > > > > > > > Ãâà> > > > > > > > It boots up ok, but makes very little sound the most > you > > > get > > > > > out > > > > > > of > > > > > > > it is a thump or slight squeak when you hit a key, the > > same > > > > > pitch > > > > > > > wherever you hit. The digital side seem to be mostly > > working. > > > > > > > > Ãâà> > > > > > > > If you hit autotune it comes back with '0 tuned' so it > > > can't > > > > > tune > > > > > > > any of the oscillators probably because it cant 'hear' > > them > > > so > > > > > to > > > > > > > speak. > > > > > > > > Ãâà> > > > > > > > First thoughts are some kind of DAC problem. > > > > > > > > Ãâà> > > > > > > > 2: All the LED's on the left hand side don't work at > all > > > but > > > > > the > > > > > > > buttons do. A few are just stuck on all the time, again > > the > > > > > buttons > > > > > > > work. > > > > > > > > Ãâà> > > > > > > > 3: one digit on the alpha/numeric display is barely > > visible. > > > > > > > > Ãâà> > > > > > > > 4: this is a slightly weird one which is hard to > > describe, > > > > > when > > > > > > you > > > > > > > move the pots the numbers in the alpha display move up > and > > > down > > > > > > which > > > > > > > is correct., however say you turn oneÃâàpot and move to > > > another, > > > > > > > wellÃâàthe first pots status doesn't clear from the
> > display, > > > > it's > > > > > > > stuck there, you can see it flicker as you move the > other > > pot > > > > > but > > > > > > > it's stuck there unless you go back and zero > theÃâàoriginal > > > pot. > > > > > > Only > > > > > > > a few pots seem toÃâàcause this problem. > > > > > > > > Ãâà> > > > > > > > Any ideas would be helpful. Obviously the first thing > im > > > > going > > > > > to > > > > > > > check is the PSU when I open it up later. > > > > > > > > Ãâà> > > > > > > > Thanks, Phil. > > > > > > > > Ãâà> > > > > > > > > > > > > > > > Send instant messages to your online friends > > > > > > > http://uk.messenger .yahoo.com > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > >
2008-11-03 by gerryrdahl
That sounds great! I know the feeling of repairing someone elses repair. It can be madning! Sounds like you are well on your way. The rom version you have I believe is 1.6. This is the pre "autotune update" version. Some folks say this is the more desirable version. Let us know how the final tuning goes. GD --- In vintagesynthrepair@yahoogroups.com, "eggwheatis" <eggwheatis@...> wrote: > > > > > --- In vintagesynthrepair@yahoogroups.com, Philip <eggwheatis@> > wrote: > I found it. Connector P28 was plugged in backwards on the Common > Analogue board. :o) > > Dare I say it's almost 100% fixed?? > > Just got to tune the filters tomorrow! > > Thanks, Phil. > > > > The problem is when you go into MONO mode, the filter stops > tracking across the keyboard. The 1/3 and 2/3 KB Tracking buttons in > the filter section have no effect. It's tracks ok in polyphonic mode. > >  > > Also in Poly mode switching the 2/3 KB Tracking button on in the > filter section makes the third oscillator drop almost one octave > across all 6 voices. > > > > So what do you reckon? > > > > Thanks< phil. > > > > > >  > >  > >  > > > > > > --- On Sat, 1/11/08, gerryrdahl <gerryrdahl@> wrote: > > > > From: gerryrdahl <gerryrdahl@> > > Subject: [vintagesynthrepair] Re: Memorymoog repair > > To: vintagesynthrepair@yahoogroups.com > > Date: Saturday, 1 November, 2008, 12:50 PM > > > > > > > > > > > > > > Hi Phil, > > What are the readouts for the Osc's? > > When you press c-7-enter-enter- 1-1, what does the display read? > > If it reads dead osc or LOW, check the others and see what > > you get. > > You may have a CTC osc scanning problem, where the CTC cannot > > count (or check the tuning) on the osc's. > > > > Also what version firmware do you have? > > When you do a c-0-enter all the leds blink, in the patch readout > > will be a flashing number, this is the version. > > > > Also check the pitch bend and fine tune circuit. > > These are supposed to be disabled during autotune. if not > > then the MM will not tune. > > > > Let us know. > > GD > > > > --- In vintagesynthrepair@ yahoogroups. com, Philip > <eggwheatis@ ...> > > wrote: > > > > > > Hi, i just started back tonight on it.... After a a very > expensive > > purchase ofàsome CEM ic's I have all the voices working on it > now. > > > à> > > I was seriously scared off putting the new IC's in in case they > > died again...but I bit the bullet and all seems fine. Phew! > > > à> > > SO now I have a fully working but seriously out of tune > > Memorymoog. The autotune wont tuneàit..too far out. I just > get '0 > > tuned' > > > à> > > I checked the calibration out in the manual and I found it a bit > > confusing... > > > à> > > Has anyone got any tips on calibrating it? > > > à> > > Thanks, Phil. > > > à> > > > > > > > > --- On Tue, 21/10/08, gerryrdahl <gerryrdahl@ ...> wrote: > > > > > > From: gerryrdahl <gerryrdahl@ ...> > > > Subject: [vintagesynthrepair ] Re: Memorymoog repair > > > To: vintagesynthrepair@ yahoogroups. com > > > Date: Tuesday, 21 October, 2008, 4:13 AM > > > > > > > > > > > > > > > > > > > > > Hi Phil, > > > How has the Memorymoog turned out? > > > > > > Did the replacement CEM's and a calibration finish her up? > > > > > > Would like to know. > > > > > > Thanks. > > > GD > > > > > > --- In vintagesynthrepair@ yahoogroups. com, "eggwheatis" > > > <eggwheatis@ ...> wrote: > > > > > > > > Phew..I fixed the pot problem, well I think I have. > > > > > > > > I ended up taking every board out and going through them with a > > > fine > > > > toothed comb, I cleaned any surplus flux off, checked > > > > everything.. scoped everything. I just could not find it. > > > > > > > > Then something occured to me..like many things do when > repairing > > > > stuff!..on the schematics there is an LF351 op-amp on the > output > > > of > > > > the DAC..but it the actual socket was a TL071 which should be > > > fine, > > > > and i had already swapped it out..anyway it is an equivalent > and > > > is > > > > even mentioned in parenthesis on the parts sheet next to LF351, > > as > > > is > > > > TL072 as an equivalent for LF353. In fact my memorymoog has > > > TL072'a > > > > and TL)71's throughout. > > > > > > > > Now I know how sensitive digital circuits are to 'equivalents' > > so > > > I > > > > put in an LF351 and bingo....it was fixed! Or so I thought > > > basically > > > > I did it again once after playing around with it after an > > > hour..now > > > > normally it did it every 30 seconds so it is 99% better and > > hasn't > > > > done it again. > > > > > > > > Maybe the DAC is faulty itself but I still don't understand how > > > this > > > > would effect the displayed pot values. Surely that's down to > the > > > A/D? > > > > > > > > Also with good news comes bad...after fixing that problem I > > > rechecked > > > > the voices..I had lost another voice! AFter finding another red > > > hot > > > > regulator on a voice board I found all three CEM3340's were > > > shorted!! > > > > Arggh!! I was feeling pretty sick considering how expensive > they > > > are! > > > > > > > > I must have shorted something out while trying to fix the pot > > > > problem...oh well.. > > > > > > > > So anyway I've got 5 CEM3340's on the way(one spare), a 3310 > and > > a > > > > 3360. After calibration that should be it. Fingers crossed X > > > > > > > > > > > > --- In vintagesynthrepair@ yahoogroups. com, "eggwheatis" > > > > <eggwheatis@ > wrote: > > > > > > > > > > Well this (hopefully)last problem is proving to be really > > > difficult > > > > > to solve. It wasnt the Zener even though it was bad. It acts > > as > > > a > > > > > regulator for the +10 vdc to the DAC from the Control > > boards... > > > It > > > > > was causing it to sit at 11.5 vdc. Changing it did nothing. > > > > > > > > > > It's one of those niggling annoying problems that seems to be > > > > > undetectable. ..its driving me nuts..I'll try to explain it > > > better. > > > > > > > > > > Basically you turn a pot on this synth and the pots value is > > > shown > > > > on > > > > > the alpha/dec LED display, you turn the second pot the > display > > > > > instantly shows that pots value..so far so good...but after a > > > few > > > > > turns of various pots, it will stick on a value and won't > > change > > > > with > > > > > the new pot movements, pressing buttons, turning other pots > > wont > > > > get > > > > > rid of it(you can see the correct values flickering behind > > > > it)..even > > > > > turning it on and off. You have to go back and find the pot > > > thats > > > > got > > > > > the value 'stuck'. Zero that pot and it's fine again. It's > > > totally > > > > > random and depends on the combination of pots and values. The > > > > actual > > > > > sound itself changes fine with the pot movement. It's just > the > > > > > displaying of the values that is a bit screwed. > > > > > > > > > > Remember is the physical displaying of the values that gets > > > stuck, > > > > > not the actual values that control the analogue parameters. > > They > > > > are > > > > > working fine. > > > > > > > > > > If anyone can help I'd really appreciate it, the schems are > > > here: > > > > > http://www.matrixsy nth.com/blog/ media/Moog/ > MemorymoogSchema > > tics/ > > > > > > > > > > The service manual is here: > > > > > http://www.retrosyn th.com/docs/ memorymoog/ mm_service. pdf > > > > > > > > > > Apart from this fault..it seems to be almost fixed. > > > > > > > > > > Thanks, Phil. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > --- In vintagesynthrepair@ yahoogroups. com, "eggwheatis" > > > > > <eggwheatis@ > wrote: > > > > > > > > > > > > A bit more fixed..:o) > > > > > > > > > > > > well actually diagnosed.. > > > > > > > > > > > > The reason all the voices were dead on one card was because > > a > > > > > > CEM3340 VCO chip was shorted, this pulled down the 7905 > > > regulator > > > > > > that sits on the edge of each voice card killing the supply > > to > > > > the > > > > > > other CEM's. I found that a CEM3360 VCA chip was also dead > > on > > > the > > > > > > same card. So after swapping a few CEM's around I know have > > > just > > > > > one > > > > > > Oscillator 3 down. > > > > > > > > > > > > After that I noticed the VCF adsr wasnt working on one > > voice. > > > A > > > > > > quick look at the schems revealed it is generated by a > > CEM3310 > > > on > > > > > > the contour generator board. Sure enough I found the 3310 > > was > > > > dead. > > > > > > > > > > > > So that, on the face of it, appears to be the voices sorted > > > out. > > > > Im > > > > > > sure I'll find more problems. > > > > > > > > > > > > The synth is still totally out of tune, so it will need > full > > > > > > calibration. I'm not going to try that until I have located > > > all > > > > the > > > > > > CEM chips I need. > > > > > > > > > > > > I also swapped all the HC ic's out for the correct LS > > versions > > > > and > > > > > > anything that isnt specified in the parts list. For > instance > > a > > > > lot > > > > > > of the op amps are 1458's, the schematics and parts list > > > specify > > > > > > 4558. The manual also has an addition saying you should > swap > > > any > > > > > > found to 4558. The 4558 is apparently superior. > > > > > > > > > > > > I still have the problem with the displayed pot values, I > > > talked > > > > > > about in an earlier post(below). It drove me mad..I checked > > > out > > > > the > > > > > > whole of the POTPOS circuit, the MUX circuit..the display > > > > > > circuits.... eventually after forgetting theory, schematics > > and > > > > just > > > > > > randomly testing things, I found CR1 to be open on the DMUX > > > > board! > > > > > > It's a 6.2 Zener..I avent changed it yet as I was going > > > out..but > > > > > > after checking the schems I reckon I might have solved > > > it..it's > > > > not > > > > > > mentioned in the service manual, and it's right on the edge > > of > > > > the > > > > > > schems.. > > > > > > > > > > > > Thats it for now..Phil. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > --- In vintagesynthrepair@ yahoogroups. com, "eggwheatis" > > > > > > <eggwheatis@ > wrote: > > > > > > > > > > > > > > Fixed the hopeless switch matrix :o) there was a ribbon > > > cable > > > > > > plugged > > > > > > > in the wrong way round into the common analogue board! > > Large > > > > > > repairer > > > > > > > error #5..... > > > > > > > > > > > > > > So now all the button functions work properly and I have > > > > > > Oscillator 3 > > > > > > > back!... although only 4 voices working. > > > > > > > > > > > > > > I also changed 4 of the hc138's to LS138's and the filter > > > has > > > > now > > > > > > > started tracking the keyboard properly...I discovered two > > > > HC377's > > > > > > on > > > > > > > the digital board too..they should be LS variants again... > > > > > > > > > > > > > > So basically im left with OSC 1,2 and 3 not working on > the > > > same > > > > > > voice > > > > > > > card(3 dead cem3340's on the same card surely not? I > hope) > > > OSC > > > > 3 > > > > > > dead > > > > > > > on one other card. Hopeless autotune '0 tuned' all out of > > > tune > > > > > > with > > > > > > > each other even on the same cards... > > > > > > > > > > > > > > Oh and the weird pot problem: when you > > > > > > > move the pots the numbers in the alpha display move up > and > > > down > > > > > > which > > > > > > > is correct, however say you turn one pot and move to > > > another, > > > > > > > well the first pots status doesn't clear from the > display, > > > it's > > > > > > > stuck there, you can see it flicker as you move the other > > > pot > > > > but > > > > > > > it's stuck there unless you go back and zero the original > > > pot. > > > > > > Only > > > > > > > a few pots seem toÃâ cause this problem. > > > > > > > > > > > > > > I reckon swapping out those wrong HC ic's will cure > > > > that..maybe. . > > > > > > > > > > > > > > Im sure I'll find more problems too. It's amazing > > > how 'previous > > > > > > > repairer error' can completely disable a synth that > > probably > > > > only > > > > > > had > > > > > > > a couple of faults to start with. > > > > > > > > > > > > > > Getting there... > > > > > > > > > > > > > > > > > > > > > > > > > > > > --- In vintagesynthrepair@ yahoogroups. com, "eggwheatis" > > > > > > > <eggwheatis@ > wrote: > > > > > > > > > > > > > > > > Well ive now got sound out of it :o) this is going to > be > > > fun > > > > > > > > though...yet again someones been in this before me that > > > looks > > > > > > like > > > > > > > > they weren't on the ball. All the IC are in > > sockets...but > > > > most > > > > > > of > > > > > > > > them have been replaced sometimes with the wrong > variant. > > > > > > > > > > > > > > > > No sound was indeed caused by the PSU....an > electrolytic > > > > > > capacitor > > > > > > > in > > > > > > > > the +15 circuit on the DMUX board was put in backwards. > > > > > Repairer > > > > > > > > error #1. > > > > > > > > > > > > > > > > I thought I'd start by fixing the LED's on the left > hand > > > > control > > > > > > > (LHC) > > > > > > > > board and the missing digit in the alpha display so I > > > could > > > > see > > > > > > > what > > > > > > > > was going on better... > > > > > > > > > > > > > > > > The dead/stuck on LED's were caused by one of the legs > > of > > > the > > > > > > ls378 > > > > > > > > at U8 on the LHC board being bent under itself in the > > > socket. > > > > > > > > Repairer error #2. > > > > > > > > > > > > > > > > The dead digit in the alpha display was caused by a > dead > > > > output > > > > > > on > > > > > > > > the LS273 at U1 on the LHC board. > > > > > > > > > > > > > > > > Anyway so now I can see and hear whats going on I have > a > > > > whole > > > > > > host > > > > > > > > of new problems :o) > > > > > > > > > > > > > > > > I have no Oscillator 3 at all across the board, Osc 1 > > and > > > 2 > > > > > also > > > > > > > dont > > > > > > > > work on one voice. None of the oscillators will auto- > > tune, > > > i > > > > > get > > > > > > > > the '0 tuned message'. The filter self oscillates but > > wont > > > > > track > > > > > > > the > > > > > > > > keyboard. > > > > > > > > > > > > > > > > The switch matrix is hopeless on the LHC board, buttons > > > > > activate > > > > > > > > wrong functions basically, the appegiator doesnt work > > nor > > > > does > > > > > > the > > > > > > > > hold function... > > > > > > > > > > > > > > > > Things I can see right off the bat but need to get > > spares > > > to > > > > > fix > > > > > > > are: > > > > > > > > All the 74ls138's on the digital board have been > > replaced > > > > with > > > > > > HC > > > > > > > > Cmos variants...not a good idea, these are not > > compatible > > > > with > > > > > > TTL > > > > > > > in > > > > > > > > most cases, so i would think they are causing a lot of > > > > problems > > > > > > > > (fingers crossed). You need LS in there or HCT at > > least.. > > > > > > Repairer > > > > > > > > Error #3 > > > > > > > > > > > > > > > > Also there is a TL071 missing out of a socket on the > > DMUX > > > > > > > board..this > > > > > > > > is connected to the auto tune circuit..buffers one of > > the > > > > > > outputs I > > > > > > > > think. Repairer Error #4 > > > > > > > > > > > > > > > > All in all a lot of fun! > > > > > > > > > > > > > > > > Phil. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > --- In vintagesynthrepair@ yahoogroups. com, Philip > > > > <eggwheatis@ > > > > > > > > > wrote: > > > > > > > > > > > > > > > > > > I just gotÃâàa broken Memorymoog. It's really > clean, > > near > > > > mint > > > > > > in > > > > > > > > fact, but not working. Half the reason I bought it is > > > because > > > > I > > > > > > > like > > > > > > > > a challenge :o) ..I haven't even opened it up yet so I > > > > thought > > > > > > I'd > > > > > > > > post up the problems to see if anyone has an idea. > > > > > > > > > Ãâà> > > > > > > > > It boots up ok, but makes very little sound the most > > you > > > > get > > > > > > out > > > > > > > of > > > > > > > > it is a thump or slight squeak when you hit a key, the > > > same > > > > > > pitch > > > > > > > > wherever you hit. The digital side seem to be mostly > > > working. > > > > > > > > > Ãâà> > > > > > > > > If you hit autotune it comes back with '0 tuned' so > it > > > > can't > > > > > > tune > > > > > > > > any of the oscillators probably because it cant 'hear' > > > them > > > > so > > > > > > to > > > > > > > > speak. > > > > > > > > > Ãâà> > > > > > > > > First thoughts are some kind of DAC problem. > > > > > > > > > Ãâà> > > > > > > > > 2: All the LED's on the left hand side don't work at > > all > > > > but > > > > > > the > > > > > > > > buttons do. A few are just stuck on all the time, again > > > the > > > > > > buttons > > > > > > > > work. > > > > > > > > > Ãâà> > > > > > > > > 3: one digit on the alpha/numeric display is barely > > > visible. > > > > > > > > > Ãâà> > > > > > > > > 4: this is a slightly weird one which is hard to > > > describe, > > > > > > when > > > > > > > you > > > > > > > > move the pots the numbers in the alpha display move up > > and > > > > down > > > > > > > which > > > > > > > > is correct., however say you turn oneÃâàpot and > move to > > > > another, > > > > > > > > wellÃâàthe first pots status doesn't clear from > the > > > display, > > > > > it's > > > > > > > > stuck there, you can see it flicker as you move the > > other > > > pot > > > > > > but > > > > > > > > it's stuck there unless you go back and zero > > theÃâàoriginal > > > > pot. > > > > > > > Only > > > > > > > > a few pots seem toÃâàcause this problem. > > > > > > > > > Ãâà> > > > > > > > > Any ideas would be helpful. Obviously the first thing
> > im > > > > > going > > > > > > to > > > > > > > > check is the PSU when I open it up later. > > > > > > > > > Ãâà> > > > > > > > > Thanks, Phil. > > > > > > > > > Ãâà> > > > > > > > > > > > > > > > > > Send instant messages to your online friends > > > > > > > > http://uk.messenger .yahoo.com > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > >