Vintage Synth Repair

Frank, 

Not at all, no personal jabs at you intended I
promise. I'm very sorry you feel that way. But when
you start asking what an EPROM is/does, and it takes
ten seconds to google that answer..I just feel you
needed a little bit of advice in other areas not just
the problem with the synth. If my advice upsets and
annoys you then I am sorry. I don't think your
intelligence was ever in question though! 

This is a public forum and you will often get advice
that you don\ufffdt like to hear. I post for the good of
the group hopefully and the archive, not for the
individual.  If you don\ufffdt like my advice or comments
and you feel it is a private tech consultation with
Steve, then don\ufffdt post publicly, email each other
privately. I notice all your posts are addressed to
\ufffdSteve\ufffd anyway, not the group.

Anyway I am certainly no expert by any stretch but I
do have quite good common sense and a pretty logical
brain that has got me a long way without much
theoretical knowledge. I don\ufffdt care too much how
things work, I just want to fix it fast and play
it..if you get me. I want you to fix your synth as
much as the next guy on here.

You have a problem in the digital circuit you need to
scope it or use a logic probe and for that you need to
understand logic circuits, CPU's, data, address busses
etc. I/O ports etc..decent version specific schematics
and or service data. That was advised a few weeks
ago..I suggested you do some of your own research
otherwise it'll be stabbing in the dark to help you,
not hinder you. That's all.

Philip.


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

> Philip,
> You are right. You have been taking jabs at me for
> some reason for some time now. I am an RF Engineer
> for 15 years and prior to that an RF Technician for
> another 6. I have been a musician for 30 years. I am
> a hobbiest musical instrument repaiman with mostly
> amplifiers. I build and repair computers. You are
> correct I am not an expert at the digital domain but
> I do understand more than you think. Steve was kind
> enough to talk to me without insult. If you think my
> postings are an insult to your intelligence please
> don't bother responding.
> 
> Frank
> 
>   ----- Original Message ----- 
>   From: Philip 
>   To: vintagesynthrepair@yahoogroups.com 
>   Sent: Wednesday, April 30, 2008 6:18 PM
>   Subject: Re: [vintagesynthrepair] Re: Prophet 10
> repair
> 
> 
>   Not being funny but I think we said this like 3
> weeks
>   ago....I repeated it too a few days ago.
> 
>   He has a problem in the digital domain that's
> plain to
>   see....but from the kind of things he's said he
> needs
>   to read some books on that kind of stuff, do a bit
> of
>   research etc otherwise it's stabbing in the dark
> time.
> 
>   Ok carry on I'll shut up now :) 
> 
>   --- thirteentech <thirteentech@...> wrote:
> 
>   > 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" <fsimon001@...> 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" 
>   > > <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" 
>   > > <fsimon001@> 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" 
>   > > > > <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-
> 
=== message truncated ===



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