Vintage Synth Repair

I would have to go look at the schematic, but from
memory I think that it would work.


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

> Thanks. Shouldn't I be able to Inject an audio
> generator on the coax connecting the voice board to
> the EQ board to prove the EQ board functional.
>   ----- Original Message ----- 
>   From: Stephen Jones 
>   To: vintagesynthrepair@yahoogroups.com 
>   Sent: Friday, June 06, 2008 5:56 AM
>   Subject: Re: [vintagesynthrepair] Re: Prophet 10
> dead
> 
> 
>   No sound because no stored patches.
> 
>   Put your oscilloscope on some of the VCO wave
> output
>   pins and see if there is an audio waveform there.
> If
>   there is, play some keys and see if the frequency
>   changes. If it doesn't, push the autotune button
> and
>   see if the VCO frequency sweeps as the auto tune
>   process occurs. This will tell you if the computer
> is
>   talking to the sample and holds, and if they in
> turn
>   are driving the VCO's. 
> 
>   If you get that far, put your scope on the outputs
> of
>   the VCF's, and see if there is a signal there.
> Before
>   you do this make sure that you set up a basic
> patch on
>   the front panel with VCO's turned on, mixer up, no
> VCO
>   of VCF modulation, VCF cutoff open, resonance
> down,
>   zero attack and decay of the 2 ADSR's, and so on. 
> 
>   If there is filter output, move on to the voice
>   channel VCA's, and finally the master VCA. The EQ
>   board is another common failure. 
> 
>   --- fsimon100 <fsimon001@...> wrote:
> 
>   > I truly had a great day. I replaced a 1Kx4 RAM
> and
>   > resolved my 
>   > computer problem on my P10. Now all LEDs light
> up
>   > and the unit 
>   > behaves somewhat functional. Upon turn on the
> unit
>   > goes to tune cycle 
>   > then all LEDs light up and entire panel is
>   > functional. Still no sound 
>   > but this is a great milestone. Two problems I
> see
>   > are sequential 
>   > board is dead which I think I'm on top of. This
> is
>   > PCB9 which I over 
>   > voltaged when I put the 12V regulator in instead
> of
>   > 5V (due to poor 
>   > documentation this is an option for tape or
> wafer
>   > drive). I think 
>   > this will be easy to fix but I was hoping to
> help on
>   > one clue. There 
>   > is a window showing voices 1 thru 5 and below 6
> thru
>   > 10. The top 1 
>   > thru 5 show 1,3, and 4 LEDs on continously never
>   > changing. The bottom 
>   > 6 thru 10 change as I hit the keys as if it is
>   > responding however LED 
>   > 7 never comes on. Can someone offer advice. I
> have 4
>   > CEM3310s out on 
>   > the top voice board. It is to my understanding I
> may
>   > get a noise out 
>   > if configured right to see functionality before
> I
>   > buy expensive chips.
>   > 
>   > Sorry long but I am very happy to be at this
> status.
>   > Can sequencer 
>   > shut down operation. Was curious, should I get
> sound
>   > without 
>   > sequencer.
>   > 
>   > 
>   > 
>   > --- In vintagesynthrepair@yahoogroups.com,
> "Frank
>   > Simon" 
>   > <fsimon001@...> wrote:
>   > >
>   > > I did find a chip pulling down DB4 on U311 it
> is a
>   > 6514 4K CMOS 
>   > RAM. Thank god for IC sockets. The only problem
> I'm
>   > a little confused 
>   > on a cross for it. It appears obsolete. It is
> called
>   > D444C on the 
>   > chip and 6514 on schematic. Can anyone offer
> advice
>   > on a cross.
>   > > ----- Original Message ----- 
>   > > From: fsimon100 
>   > > To: vintagesynthrepair@yahoogroups.com 
>   > > Sent: Friday, May 30, 2008 8:58 AM
>   > > Subject: [vintagesynthrepair] Prophet 10 dead
>   > > 
>   > > 
>   > > Was curiouse if anyone can offer help. I
> bought
>   > a dead P10 no 
>   > lights 
>   > > or anything. The processor is good. I put
> logic
>   > analyzer on 
>   > decoder 
>   > > output and see ROM1 (Y0) and RAM (Y5)(which I
>   > believe is the 
>   > scratch 
>   > > pad memory)active at start up. All address
> buses
>   > and Data buses 
>   > are 
>   > > active. I am not certain the algorithm. A flow
>   > chart would be 
>   > nice or 
>   > > some help with what I should see at some
>   > critical points. I am 
>   > > wondering if there is a chance the ROMs lost
>   > programming and how 
>   > would 
>   > > I know. Even if they did shouldn't lights
> and/or
>   > display come on. 
>   > And 
>   > > yes the power supplies are good.
>   > >
>   > 
>   > 
>   > 
> 
> 
> 
>