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#46
03-20-2023, 01:07 PM
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Section B ( what was between R76 tie point and tuner pin 4 wire ,also lamp m3) should be 13 ohms
Section A ( tie point and tuner pin 4 wire to tie point and tuner pin 3 / C53 ) should be 17 ohms Section c ( tie point and tuner pin 3 / C53 to far point of part to filament strings) should be 8 ohms anything way beyond this is big trouble 
__________________
=^-^= Yasashii yoru ni hitori utau uta. Asu wa kimi to utaou. Yume no tsubasa ni notte. いとおしい人のために 
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#47
03-20-2023, 04:26 PM
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Yes, that is how it is measured
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#49
03-20-2023, 08:15 PM
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Those are the filament pins. You will only get a meaningful reading on the filament pins if all tubes are in their sockets and the power switch is turned on. Don't apply power to the set, just have the switch on. That completes the circuit to the hot chassis.
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#51
03-21-2023, 08:51 AM
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OK, but I don't think you need to go quite that far. First thing I do when I find a value that is way off what is expected, is to start examining that circuit.
Once a problem is detected, I like to track it down rather than look for other problems. They might very well all be connected. Fix that first problem and any others might well be resolved. It was suggested you start with the 12CA5 because it is a crucial piece of the power supply. Check the resistance readings, soon as you find one that is waaay off (ignore the filament), trace out the connections to that pin.
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#53
03-21-2023, 01:24 PM
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I tend to agree, it has to be related somehow, from what I can see, 260v C only goes to 2 points, and is fed via a 2.2k resistor, very easy to pull down, point 1 is the audio output, where you are seeing the odd resistance checks, fed to G1 via R45 (820K) pins 2-5, the other is the horizontal oscillator, via L22 & R62 @ V10 pin1.
Of course, another suspect would be C2c, if perhaps you see a lower resistance to ground on the power supply of R45 than on pins 2-5 side, one way or another, something has to be pulling that 260v C down, and the weirdness at the audio output is a yellow alert, you have to find the red! :P
__________________
=^-^= Yasashii yoru ni hitori utau uta. Asu wa kimi to utaou. Yume no tsubasa ni notte. いとおしい人のために
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#54
03-21-2023, 04:17 PM
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OK I think I found the issue after checking resistances on 12CA5. It led me to check the C2 can electrolytic that I had cut out of the chassis and replaced with a terminal strip containing the 4 electrolytic sections. Embarrassingly, the 2.2k resistor was still attached to the c (triangle) tab on the old C2 can. So, I think if I run the resistor between the positive lead of the 100uf replaced C2 section B and the positive lead of the replacement 22uf C2 section c, that should restore voltage to 260v C. Waddya think?
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#55
03-21-2023, 05:02 PM
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Yes, that resistor feeds the 260 volt bus from the 280 volt bus.
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#57
03-21-2023, 06:47 PM
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Quote:
http://www.nj7p.org/Tubes/PDFs/Frank/093-GE/6CA5.pdf Only diff is the heater. you should not be getting 0 ohms, UNLESS you mean infinite resistance, from a pin not connected.
__________________
=^-^= Yasashii yoru ni hitori utau uta. Asu wa kimi to utaou. Yume no tsubasa ni notte. いとおしい人のために
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#58
03-21-2023, 09:20 PM
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First Light
The 2200 ohm resistor was it. It's a little bit distorted because of the angle but it's got almost full vertical deflection and about 75% horizontal...all through a 200 watt bulb. I can't thank everyone who helped out enough for hanging in there with me! So excited!!!
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#59
03-21-2023, 09:22 PM
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Congrats! Try it without the light bulb. It's limiting the power to the set way too much.
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#60
03-21-2023, 09:31 PM
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Quote:
Bob Andersen you are the man! Thank you so much for your advice and guidance!
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Linear Mode
