After a few days of dealing with crap jobs in order to keep things going and paying the bills, a beautiful woman walked through the door, seductively asking for attention. A wonderful Fender Dual Showman. I gently sat her on the bench and we chatted for a while. “I’m suffering with some strange noises” she said. Don’t worry was my reply. Admiring her various front sockets, I carefully introduced and input and, oh yeah, what a racket. Now with her bonnet up, we saw this amp was almost original. Some very strange things happened when the reverb was turned up and the tremolo changed speed and all hell broke loose. You see, the HT (high voltage) to each stage in the amp is feed from the main HT supply, via various resistors and decoupled by a few electrolytic capacitors. I call the condensers as I am a grown up. When these capdensors dry up and loose their lust for life, you end up with some very strange feedback issues on the HT supplies. This causes signals from the amps reverb, vibrato stages to be allowed to interfere with each other. So, armed with a trusty test capdensor on leads, bridging across the ones in situ, provides a quick test. Changed a handful of parts and we were back to fully working delight. With a tear in my eye, I watched as she walked out the workshop, hoping one day she may come back.
Lots a Lady, wait untill I have a vintage JCM 800. She’ll come back. If not,who cares.
Lot of luck,I meant.