Quote:
Originally Posted by dieseljeep
A hum at minimum volume usually indicates power supply hum or AC ripple getting into the B+. Disconnect the speaker and with an 8 ohm or so dummy load, signal trace the audio circuit to see where the hum originates.
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I'm not to sure what your saying by disconnect the speaker and trace. I do have 470m b- to chassis but there has to be another way to track this down. Different tubes nothing works and the chassis grounds at the tubes are super clean and soldered . Should there be voltage from chassis to b- , because I'm getting about 239 Vdc at those points.