Old Muntz TV for sale Locally to me, Should I pick it up?

[vortalexfan]

Originally Posted by Kevin Kuehn

Also, leaving the 1 meg carbon comp resistor going to the CRT anode button original is asking for trouble. Only after you change it will you know if it's contributing to your voltage sag.

Tuner voltage issue - Looking at Sams schematic the tuner gets it's b+ from the voltage derived on the cathode(pin 8) of the 6V6 audio output tube(V12). A starting point would be to measure V12 pin 8 relative to ground, then R13 feeds that voltage to the tuners RF amp, mixer, and oscillator. So verify that you have the same voltage on one side of R13 as you do on pin 8 of V12. Next measure on the opposite side of R13 and see how much lower the b+ is at that point. Then from that point forward, R10 splits off b+ to the mixer tube( one half of V2) and R12 feeds b+ to the oscillator(the other half of V2). So measuring on both sides of those 3 resistors(all referenced to ground) should give some indication of where you're dropping too much b+ to the tuner.

**[edit]**

I just noticed R13 is under the main chassis(near the tuner), but R10 and R12 are inside the tuner, so would require removing the tuner cover to measure. If you get lucky, and actually the most likely is the problem will show up right around R13. According to your earlier voltage measurements there's not much drop in voltage between the 6AK5 and 6J6.

I just measured the Voltage from Pin 8 of the 6V6 in reference to Chassis Ground and I got 158.4 VDC and then on the input side of R13 I got 158.4 VDC as well, and then on the output side of R13 I got 154.4 VDC so only a 4 VDC drop between Pin 8 of the 6V6 tube and R13's output side.

I already have the cover removed on the tuner so I just need to figure out which resistors in the tuner are R10 and R12, so I can measure them.

[Kevin Kuehn]

Originally Posted by vortalexfan

I just measured the Voltage from Pin 8 of the 6V6 in reference to Chassis Ground and I got 158.4 VDC and then on the input side of R13 I got 158.4 VDC as well, and then on the output side of R13 I got 154.4 VDC so only a 4 VDC drop between Pin 8 of the 6V6 tube and R13's output side.

I already have the cover removed on the tuner so I just need to figure out which resistors in the tuner are R10 and R12, so I can measure them.

Apparently something has changed since you measured last with the tubes out. Try measuring again from the top on pins 5 and 6 of the 6AK5, with the tube out, still in reference to ground.

[vortalexfan]

Originally Posted by Kevin Kuehn

Apparently something has changed since you measured last with the tubes out. Try measuring again from the top on pins 5 and 6 of the 6AK5, with the tube out, still in reference to ground.

Well the only thing different was that the tubes were installed in the tuner when I took those measurements of Pin 8 of the 6V6 and input and output sides of R13, other than that nothing has changed circuitry wise in this TV.

[jr_tech]

There is also a possibility that the sagging/blooming high voltage slump is caused by downstream problems such as a weak horizontal output or damper tube, or perhaps the horizontal frequency being way off. In such a situation, a good strong 1B3 might worsen the symptoms, while a weak one might act as a current limiter.

I would not pitch any 1B3s biased on performance in this semi-working set.

jr

[Kevin Kuehn]

Originally Posted by jr_tech

There is also a possibility that the sagging/blooming high voltage slump is caused by downstream problems such as a weak horizontal output or damper tube, or perhaps the horizontal frequency being way off. In such a situation, a good strong 1B3 might worsen the symptoms, while a weak one might act as a current limiter.

I would not pitch any 1B3s biased on performance in this semi-working set.

jr

One could tweak the horizontal frequency slug and see if there's improvement.

[Electronic M]

Originally Posted by Kevin Kuehn

One could tweak the horizontal frequency slug and see if there's improvement.

Given the set currently has a good raster I'd recommend leaving the horizontal and HV system alone until video is made to work...If the horizontal looks off frequency with video adjust it, but don't risk messing it up until there is a clear and obvious problem.

Once he has video any small to moderate issues can be accurately assessed with a test pattern, followed by localized troubleshooting...

[old_coot88]

Originally Posted by Electronic M

Given the set currently has a good raster I'd recommend leaving the horizontal and HV system alone until video is made to work...If the horizontal looks off frequency with video adjust it, but don't risk messing it up until there is a clear and obvious problem.

Absolutely. Always tackle the most obvious problem foist.

[Kevin Kuehn]

Oh but it's so tempting to tweak.

[jr_tech]

Originally Posted by jr_tech

There is also a possibility that the sagging/blooming high voltage slump is caused by downstream problems such as a weak horizontal output or damper tube, or perhaps the horizontal frequency being way off. In such a situation, a good strong 1B3 might worsen the symptoms, while a weak one might act as a current limiter.

I would not pitch any 1B3s biased on performance in this semi-working set.

jr

Since replacing the horizontal output tube restored HV in this recent problem, I still think that is an area of concern.

jr

[Kevin Kuehn]

Originally Posted by jr_tech

Since replacing the horizontal output tube restored HV in this recent problem, I still think that is an area of concern.

jr

The horizontal frequency could be right on the edge of not wanting to resonant. Pretty common to be a little off after a full recap.

[vortalexfan]

Originally Posted by jr_tech

Since replacing the horizontal output tube restored HV in this recent problem, I still think that is an area of concern.

jr

Well the horizontal output tube that's in the TV now that brought back the High Voltage is the Original Meck Branded 6BG6G tube and the one that I had in there when I lost my high voltage was a NOS Tung-Sol 6BG6GA tube.

The horizontal Oscillator Tube which is a 6SN7GT which is an older RCA Replacement from the late 1950s that tests near the bottom of the good zone of my Tube Tester may also be causing problems as well, which I have a NOS Tung-Sol 6SN7GTB tube but the middle keyway pin is busted on it so I don't know if I can install it correctly for it to work in my set.

As for the horizontal frequency it's about as centered as it's going to get.

[vortalexfan]

Here's a picture of what the picture looks like now.

See picture below.

[old_coot88]

Originally Posted by vortalexfan

Here's a picture of what the picture looks like now.

Izzat pic with the doorknob in circuit?

[Kevin Kuehn]

Wow, whether this TV is working or doesn't is making my head spin. That's a respectable picture you have there right now, although it could be a tad brighter. Where was the brightness set for that picture?

[bandersen]

Maybe, but if you do need a replacement, there are used and NOS on ebay for much less.

https://www.ebay.com/itm/500pF-20-00...S/333120846632