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City: Cumming, GA
In need of some help on a GE model GD630. Replaced the filter caps and all the paper caps, did not change the brown mica caps and only 4 resistors. All the tubes have been checked and are good. It has a Ballast tube BL-49B, the voltage drop across pins 8&3 is 46.4v and pins 7&8 is 4.7v it is about 2v lower than it should be but steady.
Now the part that has got me going in circles. I turn it on and I get a hum (after it warms up) not real loud but its there as I turn up the vol and get nothing until about 75% rotation on the pot (10k checks out ok) I get sound (stations) but the vol is loud and distorted. All the heater voltages look good (maybe low about 1v) . Could I have the polarity of the filter caps reversed? Bad resistors? When I got the radio the filter caps were missing. Tried to go by the voltage chart but nothing matches up. Any idea's
Eric
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City: Roslyn Pa
Hi Eric,
Measure the voltage from pin 8 of the 25L6 - lead to pin 3 and then pin 5. What are the two voltages?
Terry
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
Posts: 451
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Joined: Nov 2011
City: Cumming, GA
hey Terry
should I be reading ac or dc for the voltage chart?
8-3 131vdc (19vac)
8-5 15vdc (3.1vac)
Posts: 7,295
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Joined: Dec 2009
City: Roslyn Pa
Sorry meant to put DC volts. Well those look good so I think the output stage is working ok. You said that you've got some voltages that aren't what they should be. Where are they? This set is a little odd in that the volume control is actually a rf / if gain control. All your tube test good?
Terry
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
Posts: 451
Threads: 85
Joined: Nov 2011
City: Cumming, GA
tested the tubes with a hickok 6000a but can redo, infact I will retest
using the voltage chart and not being sure which is the screen so on
6sk7 pin 3-3.3vdc, pin4-8vdc, pin6-93vdc
6a8g pin4-93vdc, pin5-10vdc, pin6-133vdc
this is to the B- which is ground?
Posts: 451
Threads: 85
Joined: Nov 2011
City: Cumming, GA
Retested the tubes all were 80% or better
Thought I found the problem when I found some brittle and crumbling insulation that looked to be grounding to the chassie but it made no difference
Posts: 451
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Joined: Nov 2011
City: Cumming, GA
If anyone is still looking at this thread I have some questions on the print?
The main filter caps I believe the positive side is where the RED jumper is (polarity is unmarked)? And why is the RED jumper there?
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State, Province, Country: PR
I don't think the drawing is saying that there is a jumper. Its simply indicating that both of those wires=red. Yes, that's the positive of each cap section and they are electrically tied together.
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