Finding this old guitar amp in a local charity shop, it dates from ~1989/early 90's and Made in England.
Alas, once home (and it was a heavy carry ~20kg?), the mains power turned on and lit the power switch, but no sound came from the speaker. The only hum was the mains transformer - linear old skool, no SMPS here! Without circuit diagrams, I challenged myself to try to fix it.
"Relatively" simple innards, with two stage gain via two separate TL072 opamps, through three channels of RC passband equalisation and a very nice Accutronics wire spring reverb (no digital effects!), plus an LM386 audio amp and extra TL072 for good measure, with two 2N0355 power transistors in the finals.
Inside, two blown 3A fast fuses suggested overcurrent somewhere on the single-sided through-hole PCB. There was indeed a short across +32V and ground, and trial and error located it in the relevant large 2200uF ripple capacitor. Replaced and back to great working order. Sprayed the pots with cleaner, added new fuses. The amp is vintage and sounds awesome!
(republished, to include some extra repair footage of the ripple capacitors)
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