Help removing jail bars from Zenith 19JC55Z - Videokarma.org TV - Video

TinCanAlley · #1 07-09-2012, 12:04 PM

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

kx250rider · #2 07-09-2012, 12:22 PM

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

sampson159 · #3 07-09-2012, 12:37 PM

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.

TinCanAlley · #4 07-10-2012, 07:54 PM

Quote:

Originally Posted by kx250rider

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

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

TinCanAlley · #5 07-10-2012, 07:57 PM

Quote:

Originally Posted by sampson159

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.

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.

jstout66 · #6 07-11-2012, 05:32 AM

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

kx250rider · #7 07-11-2012, 11:37 AM

Quote:

Originally Posted by TinCanAlley

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

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

. It was definitely an electrolytic; not one of the paper or mylar caps.

Charles

TinCanAlley · #8 07-11-2012, 02:11 PM

Quote:

Originally Posted by kx250rider

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

. 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.

TinCanAlley · #9 07-11-2012, 02:13 PM

Quote:

Originally Posted by jstout66

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

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.

TinCanAlley · #10 07-18-2012, 04:41 PM

Bump

DavGoodlin · #11 07-19-2012, 08:46 AM

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.

TinCanAlley · #12 07-19-2012, 02:13 PM

Quote:

Originally Posted by DavGoodlin

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.

dieseljeep · #13 07-19-2012, 08:56 PM

Quote:

Originally Posted by DavGoodlin

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.

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

TinCanAlley · #14 07-19-2012, 11:11 PM

Quote:

Originally Posted by dieseljeep

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!

radiotvnut · #15 07-19-2012, 11:49 PM

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.