Vintage Synth Repair

----- Original Message -----

From: Stephen Jones

To: vintagesynthrepair@yahoogroups.com

Sent: Monday, April 28, 2008 12:14 AM

Subject: Re: [vintagesynthrepair] Re: Prophet 10 repair (was Hi from a new member).

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@neo.rr.com> 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" ..> 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" 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" 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"
> > > > > 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"
>; > > > wrote:
> > > > > >
> > > > > > Hi Steve,
> > > > > > I have a manual I downloaded from
> paintingwithsound.com. It is
> > > > hard to read. I was a little disappointed
> when
=== message truncated ===

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