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Peavey PV4C slave amp

Unused for a year and then switching on , nasty magnetisation type noise and "B" 1.2 amp thermal breaker trips out. This disengages mains Tx secondary middle from ground , via a triac system crowbar fashion. Selecting DDT disabled, then amp runs ok. I tried running on a variac at

60% mains, with DDT enabled , to see if it would run and then probe difference between A and B channels. Ran ok,so turned up variac progressively, but now even at 100% , amp runs normally. So presumably a cap somewhere got reformed, how to track down which one? Other than ESR meter on caps/replacing all,probing for A/B differences, anyone aware of where a failing cap or more generally zener , opamp or whatever may lie, in the DDT processing section?
Reply to
N_Cook
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** Nonsense - the triacs are used in a speaker protection crow bar.

The power amps use PSU centre taps as speaker outputs - like some QSC amps.

** What happened is that ch B produced a large DC offset when switched on, probably due to bad contacts on the many push fit connectors OR maybe a leaky coupling electro somewhere - THEN the triac crow bar activated and shorted the output.

... Phil

Reply to
Phil Allison

no bad ESR'd electros found. 2 bad spade cons on the A channel. All TO3 bolts needed tightening, 2 on different TO3 about 1/2 turn loose. Perhaps that and cleaning/reseating opamps will have trapped the problem. Reassemble and powerup again and see.

Reply to
N_Cook

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