Prodigy dead oscillator?

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Hi all, just signed up to the board. My neighbor is letting me borrow his Prodigy (ser. # >4160) and I’m starting to get used to it. It’s my first time ever playing an analog synth, and it sounds awesome! (I mostly play strings and brass, and some keyboard) I understand the basic theory of how it works, so I can pretty easily get the sounds I’m looking for, except for those phat bass lines, which brings me to my problem…

Everything seems to be working as it should except oscillator 1. which just makes a short click attack sound with no sustain. When I first played it yesterday I didn’t get any sound at all from oscillator 1. None of the switches or knobs seem to make any difference, which leads me to believe that the problem is in the main oscillator area.

I have the back off and the solder joints on the back of the PCB look OK, but before I take all the knobs off to get at the front side I’d like to ask your advice. Is this a common problem likely involving the replacement of a part or 2? And does it sound like something I can diagnose by measuring the voltages on the schematic?

I have some experience working on Hammonds/Leslies and tube guitar amps, but this is my first time working with transistors… :open_mouth: any help will be greatly appreciated!

Thanks
Andrew

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Andrew,

Welcome to the board.

Fwiw, sometimes someone phrases their questions so completely, all of us are stumped as to what to suggest.
Yours is one such example.

The only thing I can suggest is that you consider the instrument was just moved and the problem may be physically based.

As for measuring voltages, you might consider using the voltages posted in the service manual and perhaps read what OSC 2 is doing at different nodes.
If you observe wildly different voltages, it’s fair to say something’s wrong.
However it could be either a bad component or physical connection (short or open) causing it.
While not a perfect technique for all repairs, you might consider tapping on the board while (trying to) listening to OSC 1.
You might discover (or eliminate) it being something physical.

Good luck,
Kevin

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Thanks for the suggestions, Kevin.

I should have time to take a look at it by the end of the week; I’ll post back what I find.