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Old 10th Nov 2019, 12:05 pm   #63
ms660's Avatar
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 10,707
Default Re: Vintage Radio and Phonograph cutter schematic

No hum with the volume control turned down and massive hum with volume turned up suggests 50Hz hum, sometimes caused by a screened lead that has lost it's ground connection or a control grid that's floating, ie: no or extremely high resistance to ground, other causes could be heater/cathode leakage in a valve.

Hum problems can be difficult to diagnose via the internet.....Is the hum level the same on Radio and Pickup?

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