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Philco model 77
#9

Well hmmmmm. Have you replaced any of the caps in the power supply? HV seems good but the bias voltage is pretty low. Try measuring the voltage from pin 1 or 4 to pin 3 w/ the neg lead at 1 or 4 and the plus at pin 3. See if you get a higher reading there for the bias voltage. Seems like your driver and output transformers are good. Both 45's should have the same voltage on the plate, I would suspect that one of your 45's is weak ( the one w/the higher plate voltage). You can try switching the two tubes around and see if same tube have higher voltage on it in the other socket. We need to sort the bias voltage issue out as it's causing the 45's to draw current than they need to.

GL

When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!

Terry


Messages In This Thread
Philco model 77 - by flatheadjr - 09-14-2016, 10:24 PM
RE: Philco model 77 - by flatheadjr - 09-14-2016, 10:25 PM
RE: Philco model 77 - by Arran - 09-16-2016, 03:17 AM
RE: Philco model 77 - by flatheadjr - 09-16-2016, 09:52 PM
RE: Philco model 77 - by Arran - 09-17-2016, 03:50 AM
RE: Philco model 77 - by flatheadjr - 09-17-2016, 08:25 PM
RE: Philco model 77 - by Radioroslyn - 09-17-2016, 09:21 PM
RE: Philco model 77 - by flatheadjr - 09-17-2016, 09:38 PM
RE: Philco model 77 - by Radioroslyn - 09-18-2016, 12:08 AM
RE: Philco model 77 - by flatheadjr - 09-18-2016, 12:47 AM
RE: Philco model 77 - by Radioroslyn - 09-18-2016, 02:52 PM
RE: Philco model 77 - by flatheadjr - 09-18-2016, 04:12 PM
RE: Philco model 77 - by Radioroslyn - 09-18-2016, 04:46 PM
RE: Philco model 77 - by flatheadjr - 09-18-2016, 06:11 PM
RE: Philco model 77 - by Radioroslyn - 09-18-2016, 07:37 PM
RE: Philco model 77 - by flatheadjr - 09-18-2016, 08:56 PM
RE: Philco model 77 - by Radioroslyn - 09-18-2016, 11:56 PM
RE: Philco model 77 - by flatheadjr - 09-19-2016, 12:20 PM
RE: Philco model 77 - by Radioroslyn - 09-19-2016, 01:09 PM
RE: Philco model 77 - by klondike98 - 09-19-2016, 03:01 PM
RE: Philco model 77 - by flatheadjr - 09-20-2016, 09:52 AM
RE: Philco model 77 - by flatheadjr - 09-20-2016, 11:25 PM
RE: Philco model 77 - by flatheadjr - 01-11-2017, 09:14 PM
RE: Philco model 77 - by Ron Ramirez - 01-11-2017, 09:55 PM



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