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Re: 1962 TrueTone 4DC6231-A

Posted: Fri Mar 08, 2024 11:47 pm
by Hi-Fi-Mogul
Voltages:

V1 = Left Channel 1 (noisy hum)

PIN 7 Plate VDC = 118

PIN 1 Cathode VDC = 3.4


V2 = Right Channel 2

PIN 7 Plate VDC = 122

PIN 1 Cathode VDC = 3.4

When I switch tubes b/t channels 1 & 2,
channel 1 grid1 VDC is always higher
than channel 2 grid1 VDC.

Readings of both tubes in Channel 1 position:

Grid 1 Pins 2-5 : VDC 0.11 and 0.11

Readings of both tubes in Channel 2 position:

Grid 1 Pins 2-5: VDC 0.005 and 0.004

Re: 1962 TrueTone 4DC6231-A

Posted: Sat Mar 09, 2024 12:30 am
by electra225
If you have two volt meters you can connect to the grids of both tubes. Leave the meters hooked up and let the amp run for awhile. See if the grid voltage increases as the tube gets hot. You can cover the amp with a cardboard box in order to hold in the heat. If the grid voltage increases by 1 volt or more, I'd say you have grid emissions. If it doesn't increase at all, then your problem is elsewhere.

Re: 1962 TrueTone 4DC6231-A

Posted: Sun Mar 10, 2024 3:33 pm
by Hi-Fi-Mogul
No apparent grid leak, Greg.

I'm gonna place this amp in a box for now.

I've spent a week on it, and I want to work on something
else, that will give results.

Thanks for the inputs so far, everyone.