Casio CZ/ VZ/ FZ - Pro Series

It could be a multitude of symtoms but try these first which may help  source 
the problem:
 
1. Connect your CZ to another midi sound source and see if the keyboard  
controls it, if it does then the keyboard is fine, if not then it's the keyboard  
controller IC.
 
2. Reverse this and see if the midi sound source (which has a keyboard  
preferably) plays the CZ  sounds. If yes then again its the keyboard  controller 
IC, if no then the CZ has some other internal problem, Probably the  internal 
line amplifier.
 
3. Try turning up your external amplification and see if whilst playing the  
CZ you get any clicking or hissing from your amp. If, yes then it may well be 
a  component that has failed in the amp circuit. If, no then again the 
keyboard IC  (matrix) has failed.
 
*It may well be the actual sound circuitry that has failed. In that case  you 
will be very lucky to repair it since it uses bespoke Casio IC's which  
haven't been in production for 20 years. I would recommend you refer this  machine 
to a qualified engineer in this field. It will be worth it as it's a top  
synth.
 
Hope this helps.
 
 


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