Help removing jail bars from Zenith 19JC55Z
 

I'm hoping someone here can help me. I have a Zenith Chromacolor II using the 19JC55Z chassis and the left 1/4 of the screen has vertical bars (I believe they're called "Jail Bars"). I've searched and found very little. What I did find pointed to bad caps.

I'm attaching a pic of the problem and hope this can be fixed. The set has been in the family since '77 and has had its trippler and driver board replaced. Other than those two things, she's original and still has a great picture (well, until the bars showed up).

If you need more information, please let me know. I do have the repair manual, but it doesn't have any troubleshooting section.

Thanks

Look for a 4.7uF or 10uF @ 160v or 250v electrolytic cap on the 9-88 board, if I recall (or on the 9-121 socket board if that set has an inline tube). It's been years, but I think there's another electrolytic down on the bottom section of the chassis (opposite end from the power transformer), and somewhat buried. It may even be on the upright section but toward the bottom (the side of the upright without the modules; facing the CRT). Sorry for the blurry memory on that...

Charles

i had that issue on a couple of vertical chassis zeniths.it turned out to be loose horizontal module.sylvania solid state sets also produced this same defect when the screws were loose on the horizontal/vertical module.i have this on my magnavox bicentennial set.only with direct tv box.it is fine on dvd.

My set has both of those boards. The 9-88 is the luminance board and the 9-121 is the video output board. Neither of them have any 4.7uF or 10uF caps. The luminance board has two high voltage caps... one at 100v and one at 500v. The video output has caps much higher... 500v to 1.5Kv.

Not sure where to go from here. The video output board is about a year old (it was NOS).

Does this info help?

Thanks

When I first noticed the problem, I opened the set and removed and reseated the boards. It didn't help, so I tried again using Deoxit to clean the contacts, still no help.

The caps in it are 35 yrs old and I'm sure the electrolytic ones are pretty dry by now.

man.. that's an odd symptom. I have a ton of Chromacolor modules, so if you need any, let me know which ones.......

OOPS! Brain was absent on the 9-121... I meant the 9-151. That was a System III board, but showed up in the few late Chro II sets with inline tubes.

Let me take a look at the manual on that chassis to refresh my memory... Might not get a chance til tomorrow, but now I need to know because it's bugging me :nerd: . It was definitely an electrolytic; not one of the paper or mylar caps.

Charles

Okay, the 9-88 board has 5 electrolytics. Three .47uF @ 50v, one 22uF @ 16v and one 33uF @ 25v. The rest are ceramic and mylars.

Thanks! Great to know. I spent a good month locating a 9-121. It was NOS and I got it for $10. After a lesson in adjusting the color pots, I managed to actually get a better color output than factory. The whites are so much whiter now.

Bump

The boosted B+ that screen controls get G2 voltage from has a bad electrolytic.
Possibly a sweep-derived voltage serving the video stages also.
If somebody could post a schematic of CRT and G2-video circuits, we could pick it out.

I have a PDF of the schematics. It has all the boards, part lists and circuit diagrams. Only problem is that it is too large to attach here. Which boards are you needing? Is it the video output board (9-121)? That's the board attached to the neck of the CRT. It has the master G2 and the RGB G2s. If that's the board, I might be able to copy and past that info into another smaller file.

IIRC, The boosted B+ filter cap is a section of one of the can type caps on the rear chassis.

I've attached a PDF that has a rather large chassis schematic. Is the info needed somewhere on this? I get a bit lost trying to trace things and am not really sure what I really looking for. If it is on the schematic and can be pointed out, I'm sure I could then find it on the set (well, that's the hope).

Thanks!

I'm pretty sure the boost filter is inside the multi-section power supply filter cap. If so and if that cap is bad, you'd be better off to replace the entire capacitor with individual capacitors. Trust me, I've learned this the hard way. One section of a cap will be bad, I'll isolate the bad section and add a good cap to the circuit, and then another section will fail in a week.

And how would one go about finding the multi-section cap? My best guess is that it's on the same side as the tripler, etc. Any clue as to what it might look like?

Thanks!

It's a tall, round silver can on the flat part of the chassis, next to the power transformer.

From your schematic, it looks like it would be CX228, the 10 uF 350 V cap located below the HOT on the schematic.
It's a standalone cap, buried in the chassis, not on a module. It filters the 250 V that powers the video outputs on the 9-121-01C module.

Okay, it's been awhile, but I'm finally getting around to working on this problem.

I've replaced the 10uf 350v cap (it measured out at only 4uf and appeared to have leaked some time in the past), so it was bad. While I was in there, I replaced other axial caps and removed the canister. The canister tested good, but I'm taking it to my brother's for testing with his ESR (or what ever that thing is called). I found a place that has an NOS canister, but I don't trust that after all these years it will be worth trying. I have purchased all the caps that are inside the canister and my brother will open it and replace all of them and put the back in the canister.

Let's hope this does the trick, because it started getting worse. The left 1/3 of the screen would have nice contrast and brightness, but the right 2/3 of the screen would be way too bright until it warmed up and then they would almost even out. It would still show the jail bars, though.

Anyway, I appreciate all the help and I'll let you know how it goes. Should be done by Friday.

Good luck buddy!!!

I was thinking those bars MIGHT HAVE BEEN some kind of interference and i was gonna suggest moving her and see if they were still there.. (When our neighbour used to key up his radio in the house next door many years ago we got similar RF interference on the screen which is why i wondered)


I want to wish ya the best of luck getting her fixed!!!!

Success! No more jail bars and no more uneven brightness across the screen!

So it seems it was the 10uf 350v cap, only. I tested the canister and it was good, so I put it back in.

Upon firing her up, no smoke, not sparks and no blown fuses. Yea, I didn't mess anything up while in there (not that I normally do that). :)

The only thing I had to do was run DVD Essentials and calibrate the brightness and contrast again. Picture looks beautiful!

Thanks to all here. You make my repairs a success with your input.

I love the Chromacolor sets. Always have. Never have I owned one, though.

Congrats my friend!!!!!!

Give her a pat for me would ya??

:)