#49 Joyo ZoMBie, part two - analysis and repair

It took the best part of an evening and a couple hours the next day, but i managed to lift the schematic for the whole preamp board. I also recreated the board, but that was mostly for sanity-checking. I used all the same component designators, but didn't bother measuring all the dozens of small ceramic caps, because there's only SO far i'm willing to go...

#47 Joyo ZoMBie guitar amplifier teardown

My bandmate got his hands on this Joyo ZoMBie about a week or two back; it was sold as faulty. No idea how or why, but there's something dicky with the tone control - on some power-ups it works fine, but sometimes quits working (ie. sounds like the setting got stuck at some random point along the travel of the knob), no matter how much you twist it. Power cycling sometimes helps, but inconsistently, and even if it does, it just "gives up" again, sooner or later.