Zenith flat chassis jail bars - Videokarma.org TV - Video

zeno · #1 11-13-2014, 10:00 AM

A while back someone had this problem & was never solved.
Also had one at the shop years ago but never followed up
on it.
Although its the upright chassis this refers to they are near
identical electricly. From TP-11 training manual

1) lead dress of the wiring between the 22-5001 caps.
2) getting into IF module via the 24V B+. moving the B+
wire to a different point cures it.
3) I also personally think the replacement triplers may be
the cause or other lead dress issues. It would be nice to
see a true virgin set to see the dress of the HV, yoke, CRT
and convergance as the factory made it.

73 Zeno

Jon A. · #2 11-13-2014, 07:29 PM

Mine is probably untouched electronically. Why someone took the screws out of the tab wheel though is beyond me as there's nothing wrong with the tuner. I have acquired new safety caps but haven't been able to replace the originals yet.

Once I am able to get at it, what exactly would I need to take pictures of?

rrrhre2s · #3 11-14-2014, 09:16 PM

I can't remember exactly where the capacitor is located, but I remember a set from when I was servicing those sets that had that problem.

There was an electrolytic capacitor open and just passing your hand around near the IF would change the bars.

I do remember that if the IF cable was unplugged the bars were easier to find with the O-scope.

It's terrible to get Old, nothing works like it did when you were younger.

rrrhre2s

zeno · #4 11-15-2014, 04:32 PM

Quote:

Originally Posted by Jon A.

Mine is probably untouched electronically. Why someone took the screws out of the tab wheel though is beyond me as there's nothing wrong with the tuner. I have acquired new safety caps but haven't been able to replace the originals yet.

Once I am able to get at it, what exactly would I need to take pictures of?

If it hasnt been touched photo the wiring routes of the CRT socket,
HV & focus leads, Yoke & convergance leads. If virgin the should be
held in place by wire ties etc. I always tried to get them back
where they were but most tech go lazy on that. On a Zenith
it usually dont matter but I have seen jail bars on others due to
lead dress..........

73 Zeno

zeno · #5 11-15-2014, 04:52 PM

Quote:

Originally Posted by rrrhre2s

I can't remember exactly where the capacitor is located, but I remember a set from when I was servicing those sets that had that problem.

There was an electrolytic capacitor open and just passing your hand around near the IF would change the bars.

I do remember that if the IF cable was unplugged the bars were easier to find with the O-scope.

It's terrible to get Old, nothing works like it did when you were younger.

rrrhre2s

Yes, getting old. It sucks BUT you can say almost anything & not get
into a gunfight, they think you just a crazy old fart

Interesting comment on jail bars, seems almost imposable with all the steel in a Zenith your hand near the IF strip would do that. I will dig
up the old thread & pass it along if he isnt reading this. I know its
not a one time thing, while helping on it I called our old road man.
He had one after he did some other work but the customer didnt
want to go further. Like to know myself as I do want to get a
flat chassis myself someday & knowing my luck it will have jail bars.

73 Zeno

Findm-Keepm · #6 11-15-2014, 05:07 PM

Quote:

Originally Posted by rrrhre2s

I can't remember exactly where the capacitor is located, but I remember a set from when I was servicing those sets that had that problem.

There was an electrolytic capacitor open and just passing your hand around near the IF would change the bars.

I do remember that if the IF cable was unplugged the bars were easier to find with the O-scope.

It's terrible to get Old, nothing works like it did when you were younger.

rrrhre2s

c208, a 5uf, usually a Callins. We replaced all of the Callins caps in Zeniths, as a way to prevent callbacks. 5uf 15 or 25V cap - just look for the black cap with red ends near the IF module.

zeno · #7 11-15-2014, 06:40 PM

Quote:

Originally Posted by Findm-Keepm

c208, a 5uf, usually a Callins. We replaced all of the Callins caps in Zeniths, as a way to prevent callbacks. 5uf 15 or 25V cap - just look for the black cap with red ends near the IF module.

Good to know. I just remember the NP cap in the video & another in the
AGC that caused snow IIRC. I am not a re-capper but in this case
it would have paid off.

BTW that index was in great shape & much appreciated, will
return the favor when I can........

73 Zeno

zeno · #8 11-15-2014, 07:30 PM

The old thread
http://www.videokarma.org/showthread.php?p=3081658

I dropped him a PM hopefully this will help him.

73 Zeno

Jon A. · #9 11-16-2014, 08:40 PM

Quote:

Originally Posted by zeno

If it hasnt been touched photo the wiring routes of the CRT socket,
HV & focus leads, Yoke & convergance leads. If virgin the should be
held in place by wire ties etc. I always tried to get them back
where they were but most tech go lazy on that. On a Zenith
it usually dont matter but I have seen jail bars on others due to
lead dress..........

73 Zeno

Here we go, hopefully everything's in place.

Alastair E · #10 11-30-2014, 08:07 AM

Thought--as they were Irish made, its only the UK that had these terrible black plastic bomb components...

Thorn UK/BRC (Ferguson, Baird, Ultra etc),sets were full of them. At the age they are now--Replace On Sight!!

They were suspect 30 years ago, never the best of caps....

KentTeffeteller · #11 01-04-2015, 09:34 PM

Yes, Callins Ticking Time Bombs. Replace them on sight.

TinCanAlley · #12 03-08-2015, 06:09 PM

Okay, been away for some time now. Basically gave up every fixing the jailbars.

I'm not sure what in this thread I should be doing/checking, so I'll attach pics of the areas I believe are being noted.

I'm attaching pics of the lead dress of the set when I got it. I don't know if it's factory, but I'm also attaching a pic of after the cleaning where I tried to put them all back the way I found them.

I'm also attaching a pic of the safety caps (the 22-5001 mentioned) and the bottom side of the IF module where I believe the 23.4V B+ is located on the 4th pin of the module in the upper left of the section I outlined.

So if there is anything you think I should be doing in any of those areas, please let me know.

zeno · #13 03-09-2015, 09:10 AM

Look for small electrolytics in the area of the IF
module. Black & say "Callins" on them.
Cant find my manual so must have sold it.
The 24 V line will use white/brown wiring. Zenith
did a lot of color coding back then.

73 Zeno

TinCanAlley · #14 03-09-2015, 01:30 PM

Quote:

Originally Posted by zeno

Look for small electrolytics in the area of the IF
module. Black & say "Callins" on them.
Cant find my manual so must have sold it.
The 24 V line will use white/brown wiring. Zenith
did a lot of color coding back then.

73 Zeno

Would those caps be on the top or underside? I recapped the entire chassis, minus the sound board and any in the tuner and remote receiver section.

TinCanAlley · #15 03-15-2015, 03:56 PM

Quote:

Originally Posted by zeno

Look for small electrolytics in the area of the IF
module. Black & say "Callins" on them.
Cant find my manual so must have sold it.
The 24 V line will use white/brown wiring. Zenith
did a lot of color coding back then.

73 Zeno

Any thoughts on location? I recapped the chassis, minus the modules. Are the caps on a module? If not, I must have replaced them already.

Would be nice to one day watch a space movie with out the jailbars. That's when they stand out the most.