[sdiy] Prophet 600 diagnostic eprom?

[Eric Frampton]

In the simple solutions to complex problems department: it was a bad IC socket. The spring for pin 15 of the oscillator had snapped off. The whole socket actually disintegrated as I was removing it.

Thanks again for all the assistance.

e

> On Jun 20, 2016, at 11:36 AM, mail <mail at m4moti.com> wrote:
> 
> 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:
>> 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.

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