[sdiy] Prophet 600 diagnostic eprom?

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Try taking out U431 -- Osc B 3340.  It might be that that is bad and its 
output is at DC (+6V?) that is causing OscA to get stuck at a very high 
note and thus fail to step through the tune/scale procedure.  Or check 
U433 -- that opamp might be bad.
  It might not be the switch but the input into the switch 1/4 U429.  
Read the VC at U428.15 for 0-5V.

Bulghur


On 6/19/16 22:29, Eric Frampton wrote:
> With all of your help and guidance, I've got almost all of it sorted. It was multiple issues, not one of which was on the CPU board (y’all were all right!).
>
> The LM311 comparator on the DAC was indeed shot.
>
> One of the 4051’s had gone bad and lost 4 outputs, which happened to be 4 of the voice VCA lines.
>
> Dirty sockets that had sat empty for years caused a couple of the 3340’s to speak at very high frequency. Exercising the chips in the sockets solved that.
>
> Under the magnifying glass I discovered that I actually damaged my Teensy board when I modded it. The GliGli portion of the symptoms, then, was completely unrelated after all.
>
> So now, it’s a very short list: the only thing that isn’t working is oscillator 1A. I’m guessing the Autotune routine is shutting it down because it can’t control it for some reason. I’ve got a solid signal on the related 4051 (U415) and op-amp (U421). Oddly, I’m seeing about +6V on pin 1 of U429 (the output of the 4016) which doesn’t appear on any other voice, so thinking I had a bad 4016 I swapped that. No change. Also tried swapping the 3372 for a known good one in case that 3372’s input was bad and Autotune couldn’t hear the oscillator. Again, no change.
>
> Kinda stumped again, but huge progress was made so I’m still happy. This P600 made music today.
>
> e
>
>> On Jun 19, 2016, at 8:37 AM, Tom Wiltshire <tom at electricdruid.net> wrote:
>>
>> Ah, now that *is* interesting.
>>
>> Can you give us a summary of the symptoms/problems you've got?
>>
>> T.
>>
>> On 19 Jun 2016, at 00:13, Eric Frampton <eric at ericframpton.com> wrote:
>>
>>> I bought and flashed a Teensy with that exact thought in mind (having previously flashed and successfully installed one into a client's P-600), and it didn’t fix the problem. In this case GliGli just won’t boot, which leads me to think the problem is outside the components that GliGli replaces.
>>>
>>> e
>>>
>>>> On Jun 18, 2016, at 8:12 AM, Dan Snazelle <subjectivity at hotmail.com> wrote:
>>>>
>>>> You could just do the gigli p600 teensy update and get rid of the old cpu altogether ;)
>>>>
>>>>
>>>> Best half hour I ever spent for my p600
>>>>
>>>> Sent from my iPhone
>>>>
>>>>> On Jun 18, 2016, at 12:31 AM, Eric Frampton <eric at ericframpton.com> wrote:
>>>>>
>>>>> Any of you kind folks have an image of the Prophet-600 diagnostics you’d be willing to share? I think it’s called DIAG6? I’m taking a break from digging through this OB-X to work on my P-600 now that I have 3340’s to drop in there. There’s something going on with the CPU, but I can’t seem to get to the bottom of it, and I’m hoping those diagnostics might help. I’m willing to pay for your time/energy, I just don’t want to deal with Wine Country.
>>>>>
>>>>> thanks!
>>>>> Eric
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