Vintage Synth Repair

Does sound like a logic problem to me...

Phil.


--- 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?
> 
=== message truncated ===



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