Still Having RCA 8TS30 Issues

[Chris K]

Originally Posted by Yamamaya42

It should be interesting to see what the full output of the 5U4Gs are before going into the bleeder network, as in from pins 8 (cathode positive point ) to the -100v point (transformer center tap) , should be at least 400v, if not more reading at those points.

Service data says 300V DC at pin 8. I have 295V.

[Chris K]

Originally Posted by Yamamaya42

How common is it for the larger 25w resistors to be bad? The tested OK on mine a few years ago, so I left them in. only 1 section candohm resistor tested funny at the time, which I bypassed, I should have done all 3 sections, as I now suspect the other 2 are starting to fail as well, as when the sound is at max,the picture shrinks horizontally. Granted this set had no sound OEM, but that sound not be an issue, as it has the same power system in it as TVs with sound originally.



For now, I have the audio output pulled and am using a cheap LM386 amp for sound till I address the candohm resistor issue, but, do I replace ALL the bleeder network preemptively, or leave the larger 25w resister in if it still seems good?

I could put the big, enameled wire wound back in and see if it makes a difference. The Candohm had to go...not that it was bad but they're too unreliable.

[Chris K]

Or I do have a 10K 7W I could parallel that would get me to 1300???

[jr_tech]

Originally Posted by Chris K

Or I do have a 10K 7W I could parallel that would get me to 1300???

Yes... 1304.

jr

[old_coot88]

On V124 (6AC7) horz osc. control tube, what voltages do you have on:

Pin 8 (plate) -- calls for 194 V
Pin 6 (G2 ----- calls for 105 V
Pin 5 (cathode)
Pin 4 (G1) ---- calls for 2 V negative

Cathode has 10 ohms to ground, so prob. not much there

[Chris K]

I'll check those voltages later today. I've lamented my inability to show via a video what this TV is doing but if you check out shango66 today, he's working on a Packard Bell color set with AGC issues and that TV is doing the exact thing mine is doing. I know this TV does not have an AGC circuit but maybe that narrows the issue down to a specific location. Not sure.

[Chris K]

Originally Posted by old_coot88

On V124 (6AC7) horz osc. control tube, what voltages do you have on:

Pin 8 (plate) -- calls for 194 V
Pin 6 (G2 ----- calls for 105 V
Pin 5 (cathode)
Pin 4 (G1) ---- calls for 2 V negative

Cathode has 10 ohms to ground, so prob. not much there

Plate is 216 V
G2 is 86
G1 is -1.55
Cathode is...30 V DC?

[old_coot88]

30V on the cathode?! What is the resistance-to-ground from the cathode? Print calls for 10 ohms (R194).

[Chris K]

Originally Posted by old_coot88

30V on the cathode?! What is the resistance-to-ground from the cathode? Print calls for 10 ohms (R194).

11.5ohm on the resistor. 30V on pin5 Here
s the topic area...

[old_coot88]

11.5Ω is close enough. The other end of that resistor ties to pin 2 which is ground. There should be solid continuity (zero ohms) from pin 2 to the chassis. Is there?

[Chris K]

Yes

[Yamamaya42]

you may wanna think about replacing the 10ohm resistor anyway, that 30v on the cathode is really weird!

[jr_tech]

Is your volt meter auto range and perhaps indicating 30 mili-volts rather than 30 volts?

jr

[Chris K]

No it’s 30 volts DC. Measured several times. My meter always puts a zero and a decimal and shows millivolts that way

[Chris K]

But let’s hold off on wasting brain power on speculation until I can re re recheck it