Vintage Synth Repair

When you turn the machine on the front panel should be dark with the exception of the 
[TUNE] switch. The machine boots into it's autotune mode and suppresses all of the front 
panel lights and controls while it does so. it should take 8-10 seconds if the machine is 
functional, longer if voices are way out of calibration.

Does the TUNE button LED come on when you power up?

--- In vintagesynthrepair@yahoogroups.com, "Frank Simon" <fsimon001@...> wrote:
>
> Steve,
> I have all power supplies in order. There is power to all boards. When I turn it on 
shouldn't it boot up and LED's cycle on or blink or even be switchable? The panel is dead. 
Does this sound like processor to you?
> 
>   ----- Original Message ----- 
>   From: thirteentech 
>   To: vintagesynthrepair@yahoogroups.com 
>   Sent: Saturday, April 19, 2008 1:07 AM
>   Subject: [vintagesynthrepair] Re: Prophet 10 repair (was Hi from a new member).
> 
> 
>   Each of the 5 voices on each voice board has two CEM3310 envelope generators. One 
>   controls the volume envelope of the voice, and the other controls the filter cutoff of 
the 
>   voice if you bring up the filter envelope modulation control. If the 3310's in the filter 
>   control line are faulty it should only manifest when you turn on the filter envelope 
>   modulation. If this is off then the voice should sound if the VCF cutoff pot is set open. 
If 
>   you have bad 3310's in the VCA envelpoe position, the voice won't sound.
> 
>   I am assuming that your P10 has Rev 3.x Prophet 5 voice boards in it, because in the 
>   Sequential System Technical manual which covers all Prophets from Rev 3.0-3.2, the 
>   Prophet 10 and the Poly Sequencer, they all use the same basic voice board. So for 
>   instance, in Voice 1 of the voice board, U412 is the amplifier envelope generator, and 
>   U417 is the filter envelope generator.
> 
>   --- In vintagesynthrepair@yahoogroups.com, "Frank Simon" <fsimon001@> wrote:
>   >
>   > Steve,
>   > I am pleased to know there is a technique to troube this with the bad ICs. I hope to 
get 
>   to that point soon. If I remember there were no LEDs on control panel lit when turned 
on. 
>   Is there a local spot that isolates that symptom? I haven't removed the top boards yet. 
>   Hopefully I can handle that. 
>   > 
>   > I guess I am confused on VCA and VCF envelope positions. Can you give me a 
>   explanation of how to determine which state the IC is in.
>   > Frank
>   > 
>   > 
>   > 
>   > 
>   > ----- Original Message ----- 
>   > From: thirteentech 
>   > To: vintagesynthrepair@yahoogroups.com 
>   > Sent: Friday, April 18, 2008 6:04 PM
>   > Subject: [vintagesynthrepair] Prophet 10 repair (was Hi from a new member).
>   > 
>   > 
>   > Well, if you have metered all of the power supply rails in the machine, and are 
satisfied 
>   > that they are all in spec, then go ahead and put the voice boards back in. Remove the 
>   > known bad 3310's, and if any were in VCA ENVELOPE positions, replace them with 
>   3310's 
>   > from VCF ENVELOPE positions. This will allow you to set up a patch with the VCF 
>   envelopes 
>   > control turned off and still have all of the voices audible so that you can hear is all 
the 
>   > voices are working. 
>   > 
>   > The EQ board on P10's was another source of problems too of you don't get any 
>   sound. 
>   > 
>   > As for the sequencer board, the best way to test functionality is to get the rest of the 
>   > machine basically playing and then just try out the sequencer and see if it loads and 
>   plays 
>   > back notes.
>   > 
>   > Sounds like your power supply lines are the most important issue, so as I mentioned, 
>   put 
>   > all your attention on them being correct first. There are lots of CEM3310's in the 
>   machine, 
>   > so you can definately get the machine playing without 4 of them, just make sure that 
>   there 
>   > are good chips in the VCA envelope positions.
>   > 
>   > Steve.
>   > 
>   > --- In vintagesynthrepair@yahoogroups.com, "fsimon100" <fsimon001@> wrote:
>   > >
>   > > Steve,
>   > > Thanks, obviously I have a Rev 1. My schematic is a scanned copy and 
>   > > didn't see the note and still don't but I know you are correct. What 
>   > > do you think I could have damaged with the 12v I put in? Like I said 
>   > > U931 shorted and got hot. I know that may be a tough question 
>   > > without personally probing but the board is holding the 5v now. How 
>   > > could I verify functionality of PCB9. 
>   > > 
>   > > Also if I put one of the voice boards in with 4 CEM3310 missing can 
>   > > I continue troubleshooting? Is there a chance I could get confidence 
>   > > from a oscope or panel lights before I buy four CEMs.
>   > > 
>   > > --- In vintagesynthrepair@yahoogroups.com, "thirteentech" 
>   > > <thirteentech@> wrote:
>   > > >
>   > > > The Prophet 10 service manual shows that U603 is a +5V for rev. 1 
>   > > machines, or +12V for Rev. 0 machines. It looks like that supply is 
>   > > for either a 5V 
>   > > > cassette drive or a 12V wafer drive depending on which version of 
>   > > machine you have, but the schematic also shows a note on the 5.6V 
>   > > rail of the PSU 
>   > > > saying: "To PCB 9, Rev 0, not used for Rev 1". So depending on 
>   > > whether you have a Rev 0 or Rev 1, there will be different supplies 
>   > > on P603 pins 2 and 
>   > > > 3.
>   > > > 
>   > > > 
>   > > > --- In vintagesynthrepair@yahoogroups.com, "Frank Simon" 
>   > > <fsimon001@> wrote:
>   > > > >
>   > > > > Hi Steve,
>   > > > > I have a manual I downloaded from paintingwithsound.com. It is 
>   > > hard to read. I was a little disappointed when the power supply in 
>   > > my schematic 
>   > > > states VR603 was 12v T0-3 down to the wire color. Later to find 
>   > > out as I traced it to the PCB9 Polyphonic sequencer CPU board it 
>   > > needed to be a 5V. 
>   > > > It took out a Dual Flip Flop U931. After that I put a proper 5V in 
>   > > and nothing is shorted. But doesn't mean something else was't 
>   > > damaged on that 
>   > > > board just not shorted. That same part was originally bad when the 
>   > > original 5V Reg was in then the 12V took it out again. That was the 
>   > > first 
>   > > > bonehead move. And as you may read from my first mail the CEM3310 
>   > > story. So my progress is negative. If you can offer a systematic 
>   > > approach to 
>   > > > trouble shoot this maybe by isolating boards or whatever I would 
>   > > appreciate it. If you have a readable schematic you can share it 
>   > > would be great. 
>   > > > > ----- Original Message ----- 
>   > > > > From: Stephen Jones 
>   > > > > To: vintagesynthrepair@yahoogroups.com 
>   > > > > Sent: Tuesday, April 15, 2008 9:35 PM
>   > > > > Subject: Re: [vintagesynthrepair] Hi from a new member.
>   > > > > 
>   > > > > 
>   > > > > Wow, that's a lot of questions. I can help out, but
>   > > > > not all at once, I have a workshop full of synths at
>   > > > > the moment that I am fixing 1 by 1. Starting the the
>   > > > > Prophet 10, do you have a service manual for it?
>   > > > > 
>   > > > > --- Frank Simon <fsimon001@> wrote:
>   > > > > 
>   > > > > > Hi Steve,
>   > > > > > I hope everyone doesn't attack you at once. I had a
>   > > > > > crazy experience where I bought a Prophet 10, Korg
>   > > > > > Trident Mk II, and Roland JX 10 all for $30 each non
>   > > > > > working. I am an RF engineer and novice
>   > > > > > musician/Audio repairman. I know linear more than
>   > > > > > digital but I am going to throw out some questions
>   > > > > > since you offered. 
>   > > > > > 1)My Trident I fixed due to NiCad battery meltdown
>   > > > > > destroying traces but I repaired the PC board(with
>   > > > > > wire) and all works great Strings, Brass,
>   > > > > > FLANGER!!!, but the Synth section makes occasional
>   > > > > > odd noises sounds like processing. Any trouble
>   > > > > > shooting advice would be appreciated.
>   > > > > > 2) The P10 had no sound, lit up, I found a 5V
>   > > > > > regulator pulled down. Found the bad IC(burned my
>   > > > > > finger). Then like a dumb a## I was checking -5V reg
>   > > > > > T0-220 on a voice board,slipped shorted output to
>   > > > > > input and took out 4 CEM3310. OUCH!! Still don't
>   > > > > > know why due to internal Zener in CEM3310. I want to
>   > > > > > continue toubleshooting but don't want to buy pricey
>   > > > > > chips until my confidence is up. Can I put the board
>   > > > > > in without 4 of the 10 CEM3310 and continue. I'm
>   > > > > > sure no sound but -5v reg will be up. Any advice
>   > > > > > appreciated.
>   > > > > > 3) Roland JX10 is total dead. I think power supply
>   > > > > > was good. Lower priority. This one I don't have a
>   > > > > > schematic. Do you have one?
>   > > > > > 4) Finally my Hammond H-112 had low volume and I
>   > > > > > found unplugging the Reverb tank it came back full
>   > > > > > volume. I think the reverb is ok. Do you think it
>   > > > > > could be a tube driver? Sounds odd that it would
>   > > > > > shut the amps down.
>   > > > > > 
>   > > > > > Sorry for the overload. I'm excited about these
>   > > > > > synths. If I fix one I got more than my money back.
>   > > > > > The Korg is very close. I will cry if I can't fix
>   > > > > > the P10.
>   > > > > > Thanks,
>   > > > > > Frank
>   > > > > > 
>   > > > > > 
>   > > > > > ----- Original Message ----- 
>   > > > > > From: thirteentech 
>   > > > > > To: vintagesynthrepair@yahoogroups.com 
>   > > > > > Sent: Tuesday, April 15, 2008 7:54 AM
>   > > > > > Subject: [vintagesynthrepair] Hi from a new
>   > > > > > member.
>   > > > > > 
>   > > > > > 
>   > > > > > Just wanted to introduce myself... I am a
>   > > > > > synthesizer service tech from Sydney, Australia. I 
>   > > > > > have been fixing synths since 1982, as well as a
>   > > > > > lot of touring as a keyboard tech. Currently I 
>   > > > > > have around 22 vintage machines that I play and
>   > > > > > use for recording, and have been a warranty 
>   > > > > > tech in Australia over the years for PPG, Kurzweil
>   > > > > > E-mu and Sequential. Hope I can help out a 
>   > > > > > little on the forum, and learn some new things too
>   > > > > > :-)
>   > > > > > 
>   > > > > > Steve Jones.
>   > > > > > 
>   > > > > > 
>   > > > > > 
>   > > > > > 
>   > > > > 
>   > > > > __________________________________________________________
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>   >
>