I have just found the fault on a KEF PSW 2010 (similar to 2000) and thought I'd share.
Symptom is a buzzing noise from inside the cab. It is actually the speaker protection relay making the noise. The relay is powered by a half wave rectified DC via D10 and R140 which should be smoothed by C52 (47uF 63V). C52 had dried up allowing unsmoothed voltage to reach the relay.
Symptom is a buzzing noise from inside the cab. It is actually the speaker protection relay making the noise. The relay is powered by a half wave rectified DC via D10 and R140 which should be smoothed by C52 (47uF 63V). C52 had dried up allowing unsmoothed voltage to reach the relay.
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