[NJARC] Re. Sears guitar amp

[William S Zukowski]

Sounds like a shorted output transistor.

Is the hum still there with the volume control at minimum?

If you can determine the output transistors' leads, measure the voltage across the emitter - collector leads of each transistor.  The output transistors act like a voltage divider, so you should measure 1/2 the supply voltage across each transistor.  A shorted emitter-collector will have 0 voltage across it, and the other transistor will have full voltage.  However, if it's a base-emitter or base-collector short this method may not be conclusive.  The best way is to remove at least 2 of the connections and measure the resistance between each junction.  Do this with either an older analog VOM or using the dio

Hope this helps.

Bill

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