Ready to begin on my roundie

[kc8adu]

i have some extras.
and usually on the weekends in nice weather.
6kt8 in zeniths are as failure prone as 6gh8 in rca

[mbates14]

gimme a date when you are available, and I will see what I have to do those days, and we can plan.

[mbates14]

um, i dont get the analogy. lol.

I never restored RCAs, and never had that tube. at least, I dont think. and im not sure how failure prone they are, but i do know they must be, considering that i have one thats dead. lol.

[mbates14]

got a problem. I found out that one of my TVs as a substitude for one of my 6KT8s.

I now have great color except for the impuritys. But now, I have another problem. certain scenes, ill loose horiz sync, it looks like a scrambled picture they used back in teh analogue cable days, and most scenes, it looks fine.

And sometimes youll get annoying color bands that change the hue of the whole picture at certain scenes. like the AGC circuit is getting upset because of a weak tube or something.


Any ideas what would cause this? The color is astonishing.

[mbates14]

The only time the picture goes nuts, is when there is extreme white, such as a time warner commercial or something. The picture goes nuts.

The color on cartoons looks astonishing. Movies or commercials, it lacks alot of color, the hue changes constantly. But, sometimes its great.

the pic tube RCA2000 gave me is insanly nice in picture. its like brand new. Better than some new TVs I have seen. He told me the emissions was like new. Thats admiral for you. I owe RCA2000 alot.

here is a pic:

[bgadow]

Yep, you've come a L-O-N-G way in a short time! Looking great!

RE:purity, I could not get perfect purity on my Zenith 25MC30. I had to add some "refrigerator" magnets around the edge of the screen (on the inside) and this put things right.

RE: broken tuning gear-I've got a pile of used & NOS gears, and I bet others do, too. If you could get a pic and maybe a measurement of some sort-if you could find a part # in Sams that wouldn't hurt, either.

[mbates14]

if you look closely, the convergence is kinda awful from the center to the right lateral to the corner. Id say a touch up of the 3 coil areas will fix that BUT, i broke the ferrite on one slug. and the other one seized. the ferrite slug core that I broke, tossed the blue out of alignment in the corner by the logo, but the purity is so bad, you dont notice.

Also it wont focus all the way eather, you have to turn the knob all the way clockwise to even come close to a sharp picture, i bet one of those 2.2meg, and 15meg resistors has drifted sllightly.

But, its getting better, and it can only get better from here, but im wondering from all you TV gurus here, the problem that I described earlier, is that in the AGC section?

[rca2000]

I must say, I am IMPRESSED!!

That old tube has some REAL life left in it, as I thought it did. Boy, mike, you have made some serious progress on that set!! I guess it was worth it for me, to drag that old Admiral tv, with that old CRT, home with me, from that barn in northern Michagan, last summer.I ALMOST didn't, as I had an RCA , just the CRT, ready to bring home, but, just as I was ready to load it, it fell off the two-wheeler, and broke the neck. So, as darkness was approaching, I grabbed that Admiral,took it home, and removed the chasis and CRT, later that week. (I still have that chassis. It is a '63, or so admiral chassis, with the HV cage, on the opposite side, from the power supply.).

[Charlie]

Mike,

I think the color bands you were speaking of is means you need a new 6KT8. As KC8 was saying earlier, it's like 6GH8's in RCA. They give the same problem, and always new replacing.

The color bands may come and go as you described... depending on the program, scene, or channel you are watchin. When I got my ctc15 pieced together a few months back, it had the same problem, but only on one channel. The other channels were fine. Changed the 6GH8 (6KT8 in your Zenith) and the bands went away.

You're gettin a pretty good picture there.

[mbates14]

I probably need all 3 new 6KT8s. I stuck a 6AW8 in there, and it works perfect in place of a 6KT8, even though its twice its size. That means I need 3 6KT8s

anyway, i thought it was AGC, because the service info I have says that AGC setting control not being right, or if the AGC drive is weak itll do that.

I have to turn the control all the way to the extreme clockwise to get any kind of watchable picture. The same with teh color killer control. I have to turn it all the way over just to get a decent color picture. if i turn it back, even just a hair, itll go back to black and white. and its hard to explain, but when the color is on, you can see the interlace real badly than on black and white, but on the impure part of the tube, you cant see the pic because the interleave is so bad. When I turn the color killer on, it looks fine.

The only time is does it, is when it plays a modern show. If i go to an old happy days show, or any other color program made in those days, it looks fine, something is overloading the color circuit.

[mbates14]

Jack, you know it was worth it. it saved another roundie from extinction.

hell im so happy that it works, i could pay you more money for that tube! lol.

Here is a pic of a time warner color bar, turn to channel 80 something youll see the same bar, and youll see the impurities im talking about:

as you see some of the color bars, you can tell the color circuitry is overloading, and the color control dont make much difference at all, but almost take all the color out, some scenes, there aint no color

[Charlie]

Ya might try squirtin some contact cleaner in your controls. That might help some. Have you changed any capacitors as of yet?

[mbates14]

nope. which could explain alot of things.


I havent even looked under the chassis thoroughly yet. LOL.

the only cap i replaced was a lytic in the vert circuit. which restored the picture.

it works very well for its age.

[mbates14]

I got the purity fixed!!


I hooked in a modern degausser circuit that solved the problem.

When I wrapped the coil around the inside of the tube, and degaussed it, the impurity and convergence got all wacked out.

I just turned the purity magnet, it returned to normal!! im thinking that pure spot wasnt pure at all. it was magnatized, and the purity ring made that magnatized spot look normal.

But its all better now

now, i have to do a total reconvergence.

[Charlie]

Originally Posted by mbates14

now, i have to do a total reconvergence.

Yeah, if you jack with one, ya end up having to jack with the other. In any case, you're making progress... and that's what counts!