Vintage Synth Repair

Anybody have any experience with Prophet 600 repair?  I'm working on one
for a friend.  When you turn it on, power is supplied in the correct
voltages to the right places, but no sound is produced and the LCD
screen doesn't even light up.  Every once in a while when you turn it
on, you will get a random synthesized howling from all oscillators, but
this sound cannot be affected in any way by any of the knobs, switches
or other controls - not even the pitch control or volume control!  I'm
trying to see if I can cadge a Z-80 microprocessor chip off of someone I
know, but that's pretty much pure guesswork...

BaM

--
Find out more about Rocket Park at our web page:
http://www.rocketparkmusic.com/