Ming Da MC34-AB – Chinese Valve Amplifier Repair

A fault in one of the EL34 output valves caused the failure of this Ming Da MC34-AB amplifier.  As a result of the fault some resistors overheated and the resultant smoke and fumes contaminated the valve base and damaged some of the heater wiring.

Removal of the contamination from the valve base, replacement of the faulty resistors and heater wiring, a new set of valves and adjustment of the bias restored normal operation.

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