followup for someone here with a "static" noisy one.
I got back to this one last week, after rebuilding both power amps with modern functional replacement components. Then one channel was obviously noisey. Swapping predriver boards around, same ch problem. Temp rewiring, crossed over, the outputs of the preamp board , same channel noisey. Shorting the base of the final third SEA filter transistor to ground stopped the noise but the first one was the problem Replaced X301 and X302 of each channel with leg-twisted BC547
-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on