There is a problem with the A4000 machines where some surface mount capacitors go faulty, normally causing intermittent or no audio output from the standard RCAs at the rear.
In a worst case scenario, the caps actually leak electrolyte all over the surrounding PCB, and I saw an A4000 whose PCB pads had actually been disintegrated which made replacement of the capacitors nearly impossible. I attempted the repair and only found limited success.
Electrolytic capacitors do have a short life, relative to other types of capacitors - it's one of the disadvantages to using them in designs. But I don't think Commodore ever envisgaed that we'd still be using their machines 10 years after the bankrupcy!! That means most of our machines are over a decade old, and unfortunately with that kind of age they're ripe for electrolytic capacitor failure.
To add to the misery, I think the main cause of the cap failure in the audio part of the A4000 board was due to Commodore sourcing a cheap batch of Capacitors whose quality wasn't as good.
Generally, I think serious Amiga users should now be keeping an eye on their motherboards. If a problem is spotted early enough, it can normally be recitified quite simply. If it's left to it's own devices, the leaking electrolyte causes damage to surrounding components which may cause a write-off motherboard :-(
People need to be checking for bulging or leaking electrolytic capacitors!
Brian
