The Russian markings are quite visible and there is no sign of overheating of the bases, still light brown, and the pcb around looks as new. They look brand new except for simple dragon's teeth marks, ie not repeatedly moved around. The valve set that are in here are all 2009, he took out the new ones and replaced these used ones.
Only just got around to building a Dexion support frame so I can toss these sorts of amps around with gay abandon, and not risk the bottles. I should be able to get back to it in a couple of hours. BTW: Marshall are a total bunch of arseholes. If no new PCB is available from Marshall at a reasonable price - just add a bloody fan!!!!!!!!!!!!!!!!! A single 120mm, 240VAC fan blowing directly on the OP tubes from below cures the overheating / bias runaway problem completely. It is made from UTTER CRAP!! However - uber clever fixes involving a Dremel or mounting resistors in mid air or any similar hare brained ideas are all just re-arranging the deck chairs on the SS Titanic. ** The PCB material is definitely the cause of the problem. Once force warmed and hum level risen it is reluctant to go down again from natural cooling or from freezer spray - what process is going on with in it? Now to replace by fudge fitting to in situ component leads or take the whole thing apart to replace properly? Marshall saw fit to bodge 3 resistors by cutting off the originals and flying replacement ones to the cut wires - so whats good for the goose.
C13 100V 1uF at V1(A) cathode, of all things, is highly sensitive to hot air.
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