snap almost
Cured the main troubles in valve preamp and amp, suspect EL84 and 2 badly
soldered pcb wire links (lead free solder again, note only 2 or 3 years
olkd) . But there is a low level throbbing rumble noise
obviously associated with the tremolo oscillator on the effects board, as it
cycles up and down with varying tremolo pitch and depth.
The owner lives with this but is there a simple cure, assuming its a
grounding/screening/decoupling/smoothing problem.

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Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.ne