Still Having RCA 8TS30 Issues

[Chris K]

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

[Username1]

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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?

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[Yamamaya42]

Yeah, they do look like Resistors!
yours is much cleaner! and lacking that mysterious brown stuff that came out of mine!

[bandersen]

Originally Posted by Yamamaya42

Yeah, they do look like Resistors!
yours is much cleaner! and lacking that mysterious brown stuff that came out of mine!

That's just how they are made. The brown stuff is how they sealed the ends. Seen them many times.

[Yamamaya42]

Originally Posted by bandersen

That's just how they are made. The brown stuff is how they sealed the ends. Seen them many times.

I don't mean the dark red/brown ends, I mean I could not ID the stuff on the body/ middle.
http://suzaku.live-evil.org/1500pf2.png
that's not flux. no idea where it came from. the cap was all alone not near anything else. how did that get on there, unless it came out of the cap?

[Chris K]

The sound is diminished. I have to turn it up all the way to hear a decent tone out of the Sencore VA62. I put a 47uf electrolytic in for the 20uf C224 A section. Too big? I didn't have a 22uf cap for it. It's supposed to be 20uf. The voltage on pin 5 of the 6K6 is -17.6V.

[Chris K]

Actually no there is a 22uf electrolytic there...new Nichicon

[Chris K]

Interesting thing...as I said before, the horizontal oscillator is putting out a clean 15.75 KHz sine wave but when I look at the waveform on the plate of the 6AL5 Horizontal Sync Discriminator, the waveform trace looks fine...it's just unstable and jumping all over with instability in the picture. I don't know if that means anything other than crossing the oscillator off the troubleshooting list. The 6AL5 is new and I've put 3-4 different ones in the socket with the same outcome.

[old_coot88]

Still waitin for that cold-start test on the 135V rail.

[Chris K]

Originally Posted by old_coot88

Still waitin for that cold-start test on the 135V rail.

Oh I did it. It's in this message post salad somewhere. Close to 300V DC on startup, then after 30 seconds or so, it started a slow decline over a minute down to 105V DC

[old_coot88]

Originally Posted by Chris K

Oh I did it. It's in this message post salad somewhere. Close to 300V DC on startup, then after 30 seconds or so, it started a slow decline over a minute down to 105V DC

Ah, missed it. Got a question. The junction between R186 (6750Ω) and R240 (12Ω) should go to chassis ground. Does it? And does R240 correctly measure 12Ω?

Since that junction is the neutral point between the positive and negative supplies, if it lost connection to ground, it would be "floating" and could cause really crazy supply voltage readings. Just a shot in the dark

[Username1]

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Well, I think there has to be something wrong keeping the PS from getting close to the
numbers on the schematic, I thought the audio circuit, but it doesn't look like it.... So
you may want to try doing the fire up from cold and looking for some part getting too
hot too soon, Audio output transformer, maybe primary windings leaking current to
ground. You may also want to run it with a meter on the 135V line, & pull out a tubie
one at a time, and see if a circuit lets that line come up a lot, then possibly poke
around in that circuit. (Just take out 1 tubie, then put it back & remove another
one.) You know taking out Vert. Horiz, outputs are going to make a big
change - cause they use more ampies....

Also, know that power supply problems may and often will effect many other
parts of the tv, so Horiz. jumping instability may be PS problem.....

You also could put this thing out in the yard and light it on fire, sit back & toast
a marshmallow and start another set, and be ahead of the game this time
next week..... In my book, setting it on fire is always an option.....

You also might want to cut the line from the two rectifiers before they
feed the entire set, and measure the current and see if it exceeds
what the 5U4's are rated for..... If it does, then for sure you
know there is a excessive load someplace.....


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[Chris K]

Yeah it does and I replaced it with a new 12 ohm resistor just in case although the original was just fine.

[Yamamaya42]

Something to think about, at first my 130v rail was @ only 107V – 109V, then it was suggested that I remove one side of R130 and see what effect it had, it then came up to 138v stable, pointing me to the problem area.

I also fed capacitor coupled composite video into grid 1 of the 1st video amp (after removing the 4th IF tube), at the time and got a very good picture.

[Chris K]

Originally Posted by Yamamaya42

Something to think about, at first my 130v rail was @ only 107V – 109V, then it was suggested that I remove one side of R130 and see what effect it had, it then came up to 138v stable, pointing me to the problem area.

I also fed capacitor coupled composite video into grid 1 of the 1st video amp (after removing the 4th IF tube), at the time and got a very good picture.

I'll try both of those things tonight. Previously, I sent in an IF signal through the first and then second IF stages and got a picture with the same symptoms. I haven't tried composite directly into the video amp yet.