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 > > > > > > > > > > > > > > > > > > > > > > > > > > > >
Message
Re: [vintagesynthrepair] Re: Memorymoog repair
2008-11-02 by Philip