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Vintage Synth Repair

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Prophet 600 (probably digital problem)

2006-10-20 by Brendan Haley

So, I have a Prophet 600 here that arrived broken after shipping (we have talked to the person who shipped it and he says it worked before shipping, and he will pay for repairs....and I would at least like to see if I can bring this back to life). It was also turned on with the voltage selector in the 220V position plugged into a 110V receptacle.
and the current symptoms are as follows:
when you turn it on ALL of the LEDS on the digital panel light up and stay lit and the number readout comes all on (i.e. it reads "8.8") and stays on...and no buttons react...and the keyboard makes no sound.
Basically no resetting or anything can get it out of this state.
I have gone in and checked the power supply and all the voltages seem good.
I see waveforms on all the oscillator chips.
I see clock signal on pins that are supposed to have clock signal on the digital side. (looking with a scope)
Do people think getting the service manual from Wine Country will help me?
Could the ROM be toasted? Is there any reasonable way to see if the ROM is fine? (I have a logic probe....not that I think that will help)
Any thoughts.....suggestions for strategy? Is there a way to shut down or bypass the digital side and just make sure the "synth" is working?
-brendan

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