Yes

you may wanna think about replacing the 10ohm resistor anyway, that 30v on the cathode is really weird! :scratch2:

Is your volt meter auto range and perhaps indicating 30 mili-volts rather than 30 volts? :scratch2:

jr

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

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

30 volts across a 10 ohm resistor would be 90 watts...resistor would be getting very hot! :scratch2:

jr

When I measure it next, if I’m getting the same thing I’ll post some photos of the measurements and pins. That way if I’m doing something very stupid I won’t end up dragging u guys down any rabbit holes

It is 3 millivolts. Sorry and thanks for picking up on that. My bad. The “m” next to the “V” was microscopic!

I mean 30 mV

And they seem to get smaller every year!:D

jr

You're right about that!!! I paralleled the 1.5k with the 10k resistor to bring the resistance down to 1.3k. Same symptoms although the 135 volt line came up to 105V

Not sure where we go from here. The only thing I can find off is a lower than expected voltage. Can a resistor create a stable unstable condition? If I had not bypassed it by injecting an IF signal directly into the video IF, I would suspect the tuner but that can’t be it. I guess I need to start replacing resistors in the sync and horizontal circuits even if they test ok. At the least it will eliminate them as the culprit.

I think this one may go on the back burner for a while. I’m at a dead end with it. Sometimes it’s for the best to give an old chassis a rest and stop pokin and burnin it! Appreciate everyone’s advice and interest. I’ll be back with it in a bit.

Tryin to give it a rest but just a few more observations. I put the 10BP4 back in the chassis. The symptoms are the same but I noticed it’s less of an issue when the set is cooler. When it’s in sync it’s a beautiful picture and the resolution is very good. That’s why this irks me as much as it does. If I could just get the picture stable it would be a great performer. Once it heats up the problem becomes worse. I don’t know if that means anything or points towards a resistor issue. Trying to walk away but it’s tough. This TV came with it’s original stand so it’s a real find.

I feel your frustration bro. I might've missed it, but have you checked voltages on:

V118 (6SK7) 1st sync amp ----- pertinent voltages are pins 4, 6, 8 (that's G1,G2, plate)

V119 (6SH7) sync separator --- pertinent voltages are pins 4, 6, 8 (that's G1,G2, plate)

V120 (6SN7a) 2nd sync amp -- pertinent voltages are pins 1 & 2 (that's G1 and plate)

Are those tubes lighting up good? If any are metal, they should be getting warm after a few minutes running.

Temperature related suggests drifting components. Got a can of freeze spray or such handy?

Not handy but I'll get some

I'll check those tonight. Yes they are warm and NOS but I've tried several tubes from my stash and from the parts chassis with no change.

It might be worthwhile to check all power supply voltages cold vs hot. :scratch2:

jr

Cathode is ground on all 3 tubes, so wasn't included in voltage chart.

I really don't see a smoking gun here except for the lower voltages associated with the reduced 135V line being bled off to another voltage line source.

6SK7 #4 -3.6V #6 96V #8 187V
6SH7 #4 -4.3V #6 104V #8 103V
6SN7a #1 -1.3V #2 68V

A suggestion - from a dead-cold start, with your voltmeter on the 135V source (jct. of R185/R186), turn the set on. Since the 5U4s give full B+ almost instantly, is the 135V still low? Or is there a signifigant drop as the rest of the tubes begin conducting? This would tell you if it's tubes lugging the 135V down, or something else circuit-wise.

Great suggestion. The diagnostic skills available here are an invaluable instruction. I don't know why trying that didn't occur to me...it should be a pretty revealing exercise but I guess that's part of the learning curve! I will take a look at that this evening and thank you so much for hanging in there with me.

Again, I'm not saying this is the same problem that your set has, but it's the one that MINE had, I too had a weird problem with the 135v rail being very low, it did not cause me any sync problems, but did cause tuning and contrast problems, the fault was eventually tracked to the WHITE HI-Q 1500pf caps on the IF power rail, the ones with the red ends, NOT the brown tube like ones, on mine, many of those red ends seemed to have degraded and gotten gummy, some of the caps looked like they leaked something even, after replacing only those white HI-Q 1500pf caps, my 135v rail then came up to nominal range, and things worked much better, not perfectly as my tuner is a bit weak, but much better then when I started.

Again, not saying that this is the problem you are having, but worth looking at.

The old style ceramic caps?

yes, I posted pics of the ones that gave me problems on your other thread.

http://videokarma.org/showthread.php?t=276630&page=2

I'm wrapping one up right now and all five of the 270pF mica IF coupling caps were bad. Symptom was poor gain. That might account for your tuner being weak.

Never had trouble with the white Hi-Q caps but of course anything is possible.

https://live.staticflickr.com/65535/...e45c6a24_z.jpg

I just know that a third to a half of the ones in mine had rather soft like red ends, and a weird brown sap like stuff that seemed to be coming from them, I really did not get where it came from or how it got there, other that it must have come from the cap somehow.
I can post a pic of some before they were removed later.

And yes, the 270pF micas in mine are still OEM, and most likely need to be changed, but the tuner was in poor shape as well, but did work to some degree, looking inside, I could see insulation starting to come off of the wiring inside, I did try to clean contacts, but not too much, for fear of making it worse, the pair of 150 ohm resistors in the rf amp were quite out of tol when I tried to test them, how far , I don't recall.
This set, does not get snow with no input, but does get a picture (with some slight fuzz) with a normal rf modulator, and crystal clear when I BLAST it with a Blonder Tongue micm-d.
It can do with an alignment, as it's hard to get the sound and video to tune in at the same time, though I don't have sweep marker generator, I have the digital RF generator, which I used on the Arvin TV, which ironically is the only one of my older BW sets that gets snow with no input, meaning that they all could use a touch up.

http://suzaku.live-evil.org/0415202203(1).jpg

pic of the weird brown stuff on the white caps

295V DC when first turned on and it held for 4-5 seconds and then took a steady dive down to 104V in the next minute.

.

These voltages are I think pretty far off.... How are the resistors R160, 161, 157, 228, 153, 156, 157....
I'm wondering about the -18, -2, and -100 v sources, as it looks like they are providing bias for all
the little tubies that are also using the 135V & other sources... Higher G1 voltages will
mean all the tubies conduct just a little bit more for each one.... and you know
what that means.... More Ampies being used.... and if the 3 tubies you
provided G1 voltages for, they are each a little higher..... More
ampies means B+'s all go down..... Good suggestion about
monitoring the 135V as the set warms up, I suspect it will
go down as the set gets going, no surprise there...

.

I don't have those caps in my TV...it has the resistor-like caps all of them in the 6.3V filaments to ground.

Hello there...from my read of the schematic the volts on these should be:

6SK7 #4 -4.3V #6 129V #8 165V
6SH7 #4 -5.2V #6 135V #8 134V
6SN7a #1 I don't know! #2 88V

As for resistors, 228, 153, 159, 157, 158, 160 all test dead on. I replaced 154 and 155 because they were a smidge high.

.

Yes, and did you not post these readings:

Originally Posted by Chris K View Post
I really don't see a smoking gun here except for the lower voltages associated with the reduced 135V line being bled off to another voltage line source.

6SK7 #4 -3.6V #6 96V #8 187V
6SH7 #4 -4.3V #6 104V #8 103V
6SN7a #1 -1.3V #2 68V

With each G1 a little higher than what the schematic calls for?

Anyway, Please post all the Minus Voltage Sources, I'm interested...
Thanks....



.

Higher negative G1 voltage with respect to cathode reduces plate current. Plate voltage is in reverse phase to the grid.

Yes that's what I got (I edited the should be voltage on the 6SH7 pin 4 in my previous post. It's not -18V...its -5.2V

https://imagizer.imageshack.com/v2/1...922/hHkYdH.jpg

https://imagizer.imageshack.com/v2/1...922/zYMbrH.jpg

.

Look at the voltages, Readings Vs. Schematic the readings are closer
to 0, not closer to -7V cutoff. They are increasing with respect
to cathode 0. -3v is higher than -4v.

.

These were on my +135v IF line. :tears: and caused me pure hell in my FADA, even though the parts list called out ONE type, there were 2, the white with the weird leaking, and the tube type that seemed OK.

What's in yours? :O

These things

https://imagizer.imageshack.com/v2/1...924/2pEc4v.jpg

.

Is the sound ok? You see that full water hose from the PS goes to the 6K6 through
some very small value resistors, and a low resistance output transformer....

Is C224A ok?

What voltage is on pin 5 of 6K6?

.