Vintage Synth Repair

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

From: thirteentech

To: vintagesynthrepair@yahoogroups.com

Sent: Wednesday, April 30, 2008 10:38 PM

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

It sounds like you know what you're doing, the only way to test the EPROM's (apart from
hung data or address lines) is to replace them. Have a look on some of the Prophet
websites to see if anyone has posted the EPROM images, but first eliminate everything
else by thorough faultfinding procedures.

--- In vintagesynthrepair@yahoogroups.com, "Frank Simon" ..> wrote:
>
> Steve,
> Since I downloaded the P5 service manual (it only goes to rev 3.2) I have a much better
understanding of the system. It helps to have a good service manual. Before all I had was a
schematic only of the P10. I do have an Oscope and I may borrow a logic analyzer. I have
good troubleshooting skills. I have little microprocessor troubleshooting but as long as I
understand the flow, I know address and data bus and when a part of the system is
Computer Select from a Memory Address Decoder A10-A12 to take Adress from CPU to
output data to Data Bus. So I am going to probe the tune section (since you said that is
first operation) look for CS to the timer and status output then work towards the EPROM if
it gets CS. I think I will put a wire on CPU reset to ground instead of cycling power switch.
>
> In general I need to know sequence of events but isn't that from firmware programmed
in the EPROM. That is where I need help. How do I know it is programmed properly.
>
> ----- Original Message -----
> From: thirteentech
> To: vintagesynthrepair@yahoogroups.com
> Sent: Wednesday, April 30, 2008 6:06 PM
>; Subject: [vintagesynthrepair] Re: Prophet 10 repair (was Hi from a new member).
>
>
> Yes, it sounds like your computer is not running, and you are getting random LED's
when
> you power up. Do you have an oscilloscope and any experience troubleshooting
> microprocessors? If not, you will need someone who can I think.
>
> --- In vintagesynthrepair@yahoogroups.com, "fsimon100" wrote:
> >
> > Steve,
> > I down loaded a P5 service manual. It is very helpful and much
>; > better print than the P10 schematic I have. I can now see the what
> > you meant by the subtractive synthesis gated by the CEM3310. I just
> > need to isolate why the control panel is dead. I have two LEDs light
> > up when I power up but not everytime I power up. I know the CPU is
> > good now. I'm thinking it has to be on the computer system and not
> > the Analog or synth section. Would you agree. Thanks for your help
> > and patience
> >
> >
> > --- In vintagesynthrepair@yahoogroups.com, "thirteentech"
> > > wrote:
> > >
> > > Well, I can't guarantee that the machine will run OK without the
> > sequencer, but it probably will, and is
> > > worth a try. I see one P10 for every dozen P5's that I service, so
> > unfortunately I don't have a P10 in the
> > > shop to look at directly.
> > >
> > > As for service manuals, Sequential put out a large folder called
> > the "Prophet Synthesizer and
> >; > Polyphonic Sequencer System Technical Manual" which has the
> > Prophet 5 REV 3.0, 3.1 and 3.2 service,
> > > programming guide and schematics, the Prophet 10 theory,
> > schematics and parts list, and the Poly
> > > Sequencer theory and schematics, the Prophet 5 remote service and
> > schematics, and update mod info
> > > for the Rev 3.3 update. much of the P10 section refers to the P5
> > schematics.
> > >
> > > The basic differences between a P10 and a Rev 3.x P5 are: The
> > P10's master tune is digitized whereas
> > > the P5's is connected directly to the common analog circuit. The
> > P10 also has 6k of PROM compared to
> > > the P5's 2k to allow it to scan the keys and controls better to
> > keep scanning delays down to a
> > > maximum of 11ms.
> > >
> > > So if the machine is frozen, the best thing to do is to just start
> > making sure that every CPU line looks
> > > like it is doing the right thing, and then move on to each device
> > on the data bus and see if it's chip
> > > select input is working. If it is and you have gone through all of
> > the basic troubleshooting that you
> > > would expect to do with a microprocessor circuit, and it all seems
> > to be running, then take a look a
> > > the autotune circuitry, although this is unlikely as your TUNE led
> > is not coming on.
> > >
> > >
> > > --- In vintagesynthrepair@yahoogroups.com, "fsimon100"
> > wrote:
> > > >
> > > > Steve,
> > > > Thanks. Are these diagnostics tribal knowledge or are they
> > > > documented in a manual. I do not hve the P10 manual. If I find
> > one
> > > > will it give me diags.
> > > >
> >; > > I have disconnected the Seq board so obviously your saying it
> > will
> > > > run without it. Great. One system removed. I do have a z80 CPU
> > to
> > > > swap out.
> > > >
> > > > I was thinking the record switch was a microswitch so to enable
> > >; > would be a pull down or pull up Res on PCB.
> > > >;
> > > > --- In vintagesynthrepair@yahoogroups.com, "thirteentech"
> > > > > wrote:
> > > > >
> > > > > I am not certain what the P10's last OS revision was, the
> > highest
> > > > that I have seen on a
> > > > > Prophet 5 is V9.3. Looking at the schematics of the 2 machines
> > the
> > > > CPU board is similar,
> > > > > they do have different EPROM and NV RAM chips. Also the P 10
> > has
> > > > different scanning
> > > > > circuitry because it would have an unacceptable scan delay
> > with 2
> > > > keyboards as opposed
> > > > > to the P5's 1 keyboard, which has a maximum delay of 10 Ms.
> > The
> > > > scanner also scans all of
> > > > > the buttons during each cycle.
> > > > >
> > > > > For what it's worth (not knowing if it also applies to the P-
> > 10),
> > > > to enter the CPU and RAM
> > > > > test on a late rev. Prophet 5, turn off the power, put the
> > record
> > > > switch to "enabled", and
> > > > > jumper test point 304 (MEM TEST) to plus 5V, then turn on. The
> > > > machine starts
> > > > > sequentially flashing it's LED's, to then enter the memory
> > test,
> > > > press TUNE. It runs through
> > > > > 4 tests, counting 1-4 as it does them, and finishes on 0,
> > > > indication no failures. If it stops
> > > > > on 1-4, it is indication a failure of either the scratchpad
> > RAM,
> > > > NV RAM, PROM or 8253
> >; > > > timer (1,2,3 and 4).
> > > > >
> > > > > I haven't used these tests on a P10, so I don't know if they
> > > > apply, but otherwise maybe the
> > > > > best idea would be to disconnect the sequencer board and just
> > > > start the usual traditional
> > > > > checking of the main CPU lines to see if any of the data or
> > > > address lines are hung.
> > > > >
> > > > >
> > > > > --- In vintagesynthrepair@yahoogroups.com, "Frank Simon"
> > > > wrote:
> > > > > >
> > > > > > On Brd 3 there are three EPROMs with the Z80 CPU. The first
> > > > says: 0 TEN 5.0, second
> > > > > says: 1 TEN 5.0, third says: 2 TEN 5.0 on their stickers.
> > > > > >
> > > > > > On Brd 9 there is one EPROM with the Z80 CPU. The sticker on
> > it
> > > > is not too legible what I
> > > > > do see is: SEQ (that part is clear) below it say C1 or C.1 or
> > I
> > > > was thinking maybe 2.1( if
> > > > > upper half of 2 was missing).
> > > > > >
> > > > > > Both Z80s on pin 6 CLK have 2.5MHz clock at about 4v p-p.
> > and 5v
> >; > > dc on pin 11. Does
> > > > > the EPROM lose all programming if battery dies? If so how do
> > you
> > > > reload? Will keyboard
> > > > > not boot without EPROM program. My friend today is bringing me
> > a
> > > > Z80 CPU in so I can
> > > > > swap out.
> > > > > >
> > > > > >
> > > > > >
> > > > >; > ----- Original Message -----
> > > > > > From: thirteentech
> > > > > > To: vintagesynthrepair@yahoogroups.com
> > > > > > Sent: Monday, April 28, 2008 7:47 AM
> > > > > > Subject: [vintagesynthrepair] Re: Prophet 10 repair (was
> > Hi
> > >; > from a new member).
> > > > > >
> >; > > > >
> > > > > > What is written on the stickers on the EPROMS?
> > > > > >
> > > > > > --- In vintagesynthrepair@yahoogroups.com, "Frank Simon"
> > > > wrote:
> > > > > > >
> > > > > > > I don't know. How do I find this out.
> > > > > > > ----- 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 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"
> > > > > > > > > > > <;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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> > > >
> > >
> >
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