Vintage Synth Repair

Excellent news, well done..so did you use the Ram I
suggested? Or did you find a 444?

Thanks, Phil.


--- 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.
> >
> 
> 
> 



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