Vintage Synth Repair

Which Rev. Processor board do you have? All the Rev.
3.1 and 3.2 Prophet 5's have a built in memory test,
and latest software versions also have a basic CPU
test. Which software version do you have?


--- Frank Simon <fsimon001@...> wrote:

> Steve,
> The TUNE LED does not come on. Since I am four
> CEM3310s short, should certain slots be populated
> just to get boot up? All the supplies are up. I am
> suspicious of PCB9 due to the 12v applied and you
> mentioned EQ board. There are a couple IC's that are
> warm on the EQ board but not so hot I can't keep my
> finger on it. Can you offer a couple key
> troubleshooting spots for measurements to help me
> isolate this? I'm assuming I have no way to bless
> the Processor. All I have is  an Oscope, function
> generator, and multimeter.
> 
> 
>   ----- Original Message ----- 
>   From: thirteentech 
>   To: vintagesynthrepair@yahoogroups.com 
>   Sent: Monday, April 21, 2008 12:21 AM
>   Subject: [vintagesynthrepair] Re: Prophet 10
> repair (was Hi from a new member).
> 
> 
>   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 
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