Toshiba TV Vertical Deflection Problem, Almost Fixed ?Need Ideas

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I have a Toshiba 32? TV built in 1994. Model CX32D60, chassis TAC9442.
The problem started with the picture being squeezed from both the top
and bottom of the screen so that only the middle one-third of the
screen had any picture information. It looked like an extreme version
of letterbox format. Thwacking the side of the set would cause the
picture to revert to normal size. After ten minutes or so it would go
back to one-third size whereupon another tap on the side of the TV

the picture would stay normal sized. However, most of the time it
would exhibit slight jittering, just enough to make the text crawl at
the bottom of the screen a bit difficult to read. But sometimes the
picture would lock in perfectly.

Eventually this extreme letterbox became a single bright horizontal
line in the middle of the screen. I would take to warming the chassis
of the TV using a blow dryer aimed through the back of the TV case.
Thwack, blow dryer, thwack, blow dryer, etc. This is no way to watch
TV.

I?ve Googled my TV?s problem and found some solutions on this
newsgroup. This NG is a great resource. Thanks to all that post here.

There are a couple of electrolytic capacitors in the vertical
deflection circuit that lose their integrity with age (heat cycling).
The two capacitors mentioned are C305: 2.2 microfarad 50v, and C342: 1
microfarad 50v. I bought replacement capacitors from DigiKey--
Panasonic brand with 105C temp rating and 63v rating. Parts including
shipping was $2.35. That sure beats the TV repair shop estimate of
$140.00.

I avoided electrocuting myself and replaced the capacitors and also
touched up the solder on the pins of the vertical IC and tested the
TV. Upon initial power-up I had the familiar single horizontal line.
Thwack on the side of the box. Full size picture. Crystal clear.
Looking good. Then I notice there is a thin flickering horizontal line
at the very top of the screen, but on only some channels. I also
notice the score bar used to show information during football and
baseball games and located near the top of the screen seems a bit
lower than usual. It seems like the picture is not being stretched out
quite enough. I?m thinking the set isn?t over-scanning the picture as
much as it should. Still, it?s looking much, much better than before.

The set ran for about 5 hours one night and about 4 hours the next
afternoon when I once again got the dreaded single bright horizontal
line. Thwack. Picture is full sized again. Crystal clear. Single, thin
horizontal static-ky line at the top of the screen. TV held the full
sized picture until it was shut off for the night, about another 4
hours.

What other components should I suspect is causing this problem? Any
ideas?

Re: Toshiba TV Vertical Deflection Problem, Almost Fixed…Need Ideas


The problem started with the picture being squeezed from both the top
and bottom of the screen so that only the middle one-third of the
screen had any picture information. It looked like an extreme version
of letterbox format. Thwacking the side of the set would cause the
picture to revert to normal size. After ten minutes or so it would go
back to one-third size whereupon another tap on the side of the TV

the picture would stay normal sized. However, most of the time it
would exhibit slight jittering, just enough to make the text crawl at
the bottom of the screen a bit difficult to read. But sometimes the
picture would lock in perfectly.

Eventually this extreme letterbox became a single bright horizontal
line in the middle of the screen. I would take to warming the chassis
of the TV using a blow dryer aimed through the back of the TV case.
Thwack, blow dryer, thwack, blow dryer, etc. This is no way to watch
TV.


newsgroup. This NG is a great resource. Thanks to all that post here.

There are a couple of electrolytic capacitors in the vertical
deflection circuit that lose their integrity with age (heat cycling).
The two capacitors mentioned are C305: 2.2 microfarad 50v, and C342: 1
microfarad 50v. I bought replacement capacitors from DigiKey--
Panasonic brand with 105C temp rating and 63v rating. Parts including
shipping was $2.35. That sure beats the TV repair shop estimate of
$140.00.

I avoided electrocuting myself and replaced the capacitors and also
touched up the solder on the pins of the vertical IC and tested the
TV. Upon initial power-up I had the familiar single horizontal line.
Thwack on the side of the box. Full size picture. Crystal clear.
Looking good. Then I notice there is a thin flickering horizontal line
at the very top of the screen, but on only some channels. I also
notice the score bar used to show information during football and
baseball games and located near the top of the screen seems a bit
lower than usual. It seems like the picture is not being stretched out



The set ran for about 5 hours one night and about 4 hours the next
afternoon when I once again got the dreaded single bright horizontal
line. Thwack. Picture is full sized again. Crystal clear. Single, thin
horizontal static-ky line at the top of the screen. TV held the full
sized picture until it was shut off for the night, about another 4
hours.

What other components should I suspect is causing this problem? Any
ideas?

There is obviously a loose connection on a component in the vertical  
section, or leading to the vertical circuit.
With the TV turned on and the back cover off, you need to gently poke around  
on the board with a non-metallic tool until you touch a component that  
causes the problem to go away.
Or...  with the TV off you should look at the solder joints with a high  
power magnifier until you find the suspect solder joints, and resolder those  
spots.
If you keep heating and cooling the TV or whacking it on the side,  
eventually some of the components will fail completely.  If the failure  
causes a bright enough horizontal line, it can burn into the CRT making a  
permanent line.  You are on the right track but you must fix it right before  
more damage is done that you can not repair easily.  



Re: Toshiba TV Vertical Deflection Problem, Almost Fixed.Need Ideas

For now, I'd like to solve the thin horizontal line of static that
happens at the very top of the screen. This seems to me to be a
component that is on the hairy edge of failing--I don't think that
poking it will cause the problem to go away--but I'm not certain.
Anybody have any other ideas on why there is a line of static at the
very top edge of the screen?

*********************

I'm only guessing at this, but I think what you're seeing is not static but
digital data.  I see the same thing at the top of my TV picture (an HDTV
signal converted to be visible on a regular analog TV).  Normally this isn't
seen because it's supposed to be above the viewing area of the picture
itself.  Closed-captioning and other information is embedded in the
"vertical blanking interval," or the brief instant between frames of video.



Re: Toshiba TV Vertical Deflection Problem, Almost Fixed.Need Ideas

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That's what it sounds like.

He should check for a bad capacitor in the vertical output as well.

--
    sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
 Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
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Re: Toshiba TV Vertical Deflection Problem, Almost Fixed.Need Ideas

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What you are seeing is line 21 which contains the closed
caption data. Most sets overscan a bit and this should be
off of the screen.

David


Re: Toshiba TV Vertical Deflection Problem, Almost Fixed.Need Ideas
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Excellent theory, and I agree. This problem is most noticable on the
local PBS station that broadcasts in HD. Also those channels that have
the 16:9 digital signal seem to show this problem the most. Local
analog stations don't have it.

Thanks to everyone for the suggestions. I'll look for the cap near the
"jungle IC"--though it's usually not mentioned when discussing my
model number TV-- and check out the low ohm resistor.



Re: Toshiba TV Vertical Deflection Problem, Almost Fixed…Need Ideas
On Mon, 20 Oct 2008 14:03:16 -0700 (PDT), powrwrap

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Look for a poor solder joint in the vertical output section.  Tap
around the inside with a non conductive thwacker where the vertical
components are and be careful to avoid electrocution. Tap on the yoke
too. Forget about the other issue until the vertical collapse is
fixed.

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