Still Having RCA 8TS30 Issues

[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.

[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.

Sorry for my ignorance here...what size and what type cap did you use for the video feed? Let me see if my limited but slowly growing knowledge of this stuff is correct...the reason for the capacitor is to protect the source from DC in the TV?

[Yamamaya42]

The exact value is not super critical, since there is so little voltage to start with, people have used a .1 or .01 film type with out problems.

[Chris K]

Originally Posted by Yamamaya42

The exact value is not super critical, since there is so little voltage to start with, people have used a .1 or .01 film type with out problems.

No change in symptoms with a composite signal into the 1st video grid. R130 is reading 180 ohms and not 150 ohm. I got the freeze spray today.

[Yamamaya42]

Originally Posted by Chris K

No change in symptoms with a composite signal into the 1st video grid. R130 is reading 180 ohms and not 150 ohm. I got the freeze spray today.

BINGO!

That is out of tolerance for 10%
and you may have others, some say that having it go higher than 20% is OK, but in my case, I checked each and EVERY resistor, using this site, https://www.allaboutcircuits.com/too...de-calculator/
If it tested within 10% or better, I marked it with green paint, if it checked below, I replaced with a new 1% resistor, This could be your problem, not sure, but It is what I had to go through

[Chris K]

Replaced the R130 resistor with a 1% 150 ohm and it is better. It's not stable, it still twitches but it hasn't gone completely out of sync like it was before. Voltage hasn't changed much but I think going through this and replacing resistors across the board in the IF circuits is something I should do. The 1500pf caps as well.

[Chris K]

I think I'm going to replace all of the resistors in the sync circuit first even if they test good when cold. I was fooling around with the freeze spray on resistors in that circuit and the picture had some transient stability.

[Yamamaya42]

Originally Posted by Chris K

Replaced the R130 resistor with a 1% 150 ohm and it is better. It's not stable, it still twitches but it hasn't gone completely out of sync like it was before. Voltage hasn't changed much but I think going through this and replacing resistors across the board in the IF circuits is something I should do. The 1500pf caps as well.

Not sure why you chose 150s to replace the 130s, as the IF is always picky, but most likely, as you go through the whole set and replace all out of tol resistors no matter what section, things will get more stable, this of course will take a lot of time, it took me 2-3 months to do mine staring with a very unstable pic, to what I have now.

[Chris K]

Those resistors are 150 ohm in my TV

[old_coot88]

There's one test you could do 'experimentally' to raise the 135V source, just to determine whether the problem is due to low voltage there, or not. Just clip open either end of R186c (6750Ω), and insert a resistor in series with a pair of clip leads. I would try first a 1K, then a 2.2K, and maybe a 3.3K, all at least 2 watt rated. If raising the voltage doesn't help the problem, then you know. Just re-connect R186 and pursue another route.

[Chris K]

I’ll give it a try. I found 2 more 270pf caps in the IF (5 all together) and I will say after replacing all of them and a few low ohm out of tolerance resistors in the IF the picture is more stable. A lot of ringing, edge distortion and twitching still but noticeably better.

[Chris K]

Quick update. Still going through the chassis replacing all of the 1500pf caps in the IF and testing/replacing resistors one by one. What an impossible mess to get at these maddening things. The video IF is a crowded spiderweb full of coils, resistors, petrified insulated wiring I'm hesitant to move and the grounding caps, mostly at the bottom of it all. Fortunately, the ETF had beaucoup service data on this chassis that included a wiring diagram that has been extremely helpful.

The picture has gotten worse but I expected that. The horizontal is going to need to be realigned after all of this is complete. At this point, I don't expect to find a smoking gun where I make a replacement and bang...everything works. The video is now rolling horizontally like a sideways vertical hold issue. Looking at the service data, that's probably due to the phase control slug in T-108 needing adjustment but there are multiple tuning parameters in the horizontal circuit that need to work in concert so attempting to adjust slugs and drives right now to find the magical tuning point where everything is stable is pointless.

Someone has done extensive work on this TV throughout its lifetime and some of the component overcrowding is due to that but most of the IF is original. I don't know how any tech diagnosed and serviced this back in the day. For me, at least, it's a big challenge.

[Penthode]

Originally Posted by Chris K

I’ll give it a try. I found 2 more 270pf caps in the IF (5 all together) and I will say after replacing all of them and a few low ohm out of tolerance resistors in the IF the picture is more stable. A lot of ringing, edge distortion and twitching still but noticeably better.

The likely reason there is ringing and edge distortion is because changing the capacitors in the IF section has thrown the IF out of alignment.