Casio CZ/ VZ/ FZ - Pro Series

>Great tip, I'm investigating just now. Yesterday, magically it worked
>for some hours, so I'm pretty sure the bulk of the synth is in perfect
>condition. What would be the best way to bypass the relays? Thanks a lot :)

The relay may not be the problem- I'm not sure specifically about the CZ-1, 
but sometimes relays that are used this way only switch on when the power 
supply voltage has stabilized.  If some voltage is out of spec, or 
fluctuating, or whatever, then the relay might not turn on.

Anyway when the relay turns on or off it should make an audible click, 
though you may not be able to hear it without opening the synth up- if this 
corresponds to the audio output turning on and off, then you've found the 
source of the problem.