I am stuck on a problem with a Zenith 4-T-26 (Riders 10-7). There is no volume control. When I turn up the pot, I have no sound until I turn the pot on full. The audio suddenly comes on and is very loud. If I turn it down a small amount, the audio is gone. I have swapped out the pot with a new 3 Meg unit and still have the same problem. There is a resister to ground in the circuit, and the resister is good. Anybody have an idea what the problem is?

Hello there. 3M means 3K in 1930s terminology. Don't know the exact reasoning, but in Spanish, Mil means 1,000, and Million means what it is.

Anyway, your new potentiometer should be a 3K unit. Your old one probably has a crack in the carbon element. Disassemble it. If you need help with this, send me a photograph of the control. Carefully mend the crack in the carbon element with rear window defogger patching material (found at an automotive parts store). If you are not able to do this, simply replace the control. Since the control is likely linked to the on-off switch, it would be ideal to restore the original control, especially for authenticity.

Thomas

M = 1000 in Roman numerals.

Or that.

T.

:M = 1000 in Roman numerals.