Vintage Synth Repair

I worked on an XP50 a few months ago and had similar kinds of problems, 
the display didn't work and the likelihood was a problem with the 
contrast control system. The bad news was that a lot of the SMD 
electrolytic capacitors on the main board were leaking, failing and 
leaking a corrosive liquid over nearby components, There is a dual 
op-amp which handles both contrast control and battery monitoring and 
all the electrolytics nearby were leaking, I replaced all the SMD 
electrolytics on the main board (there were 27 if I recall) and two 
thirds of those removed were faulty according to a capacitance and ESR 
tester. Alas on this particular machine, the ASIC which drives the 
display was faulty and is unobtanium so this one bit the dust. I had 
just bought a new display and a keyboard key for it so I lost out 
heavily on that one. Forum gossip seems to hint that all the XP series 
suffer from capacitor problems.


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