tends to vent the smoke out of the power supply) However on a synth like this which has analogue output circuits but is digitally
controlled , it is disastrous to the logic circuit only in terms that it is looking for 5volts Dc not 2-3,5 volts DC( in case of low AC supply
voltage, your case). Then it does not damage any components, but it scrambles the heck out of any data written into the RAM, which is where
data gets stored, providing data for the analog circuits to perform. When you said you reset it, just exactly what did you do?
The sure fire way to "zap" the Ram is to remove the backup battery or lift either of it's leads and let it rest as long as you are patient, say overnight.
Then that only leads you to a state of a vacant RAM, therefore no sound. Next step restore the RAM via the cassette tape. If you get stuck
recontact me- somewhere I have service data and I think the debugging ROM or try the Wine Country people, they are always
friendly courteous helpful kind. regards Russ
On Oct 20, 2006, at 11:27 AM, Brendan Haley wrote:
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