Toshiba TV Vertical Deflection Problem, Almost Fixed …Need I

P

powrwrap

Guest
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
would set it right again. Once the TV was warmed up, approx. ˝ hour,
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?
 
"powrwrap" <powrwrap@aol.com> wrote in message
news:6f5e3246-8354-42b5-b0ed-bbe383dcf831@r15g2000prh.googlegroups.com...
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
would set it right again. Once the TV was warmed up, approx. ˝ hour,
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?

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.
 
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.
 
On Oct 20, 7:25 pm, "Mike S" <nospam> wrote:

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.
Click to expand...
Since the capacitors were replaced the bright horizontal line has
occurred twice--upon initial turn-on after replacing caps and once
after about 8 hours of operation. So I've only had to whack the TV two
times since replacing the caps. And I've not used the blow dryer at
all since the repair.

I did look at the solder joints in the vertical section with bright
lighting and didn't see anything amiss. Nevertheless, as long as I had
the TV opened up I did touch up the vertical IC pins. I suppose it if
happens again I could remove the back of the case and try poking
various components (instead of whacking the TV) to make the bright
horizontal line disappear and isolate the offending component.

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?
 
On Mon, 20 Oct 2008 19:20:59 -0700 (PDT), powrwrap <powrwrap@aol.com>
put finger to keyboard and composed:

I did look at the solder joints in the vertical section with bright
lighting and didn't see anything amiss. Nevertheless, as long as I had
the TV opened up I did touch up the vertical IC pins. I suppose it if
happens again I could remove the back of the case and try poking
various components (instead of whacking the TV) to make the bright
horizontal line disappear and isolate the offending component.
Click to expand...
There should be a low ohm resistor in the vertical yoke circuit. I
believe this resistor provides current feedback to the vertical output
IC. Check it for bad solder joints.

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?
Click to expand...
As someone alse mentioned, this is probably digital information
transmitted during the vertical retrace period. Here in Australia it
could be teletext. IME those lines are invariably caused by dry
capacitors in the vertical section. Just change all the caps in the
vicinity. As still another person mentioned, some Toshiba chassis also
have a problem with a low value electrolytic near the jungle IC. This
is a major multifunction IC, with 40 to 60 pins or so, which handles
colour decoding, luminance, and horizontal and vertical sync outputs.
It could have a TA prefix if it's a Toshiba part.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.
 
"Samuel M. Goldwasser" <sam@seas.upenn.edu> wrote in message
news:8wsi5b7r.fsf@seas.upenn.edu...
"Matt J. McCullar" <mccullar@flash.net> writes:

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?

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

David
 
On Mon, 20 Oct 2008 14:03:16 -0700 (PDT), powrwrap
<powrwrap@aol.com>wrote:

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
would set it right again. Once the TV was warmed up, approx. ? hour,
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?
Click to expand...
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.
 
On Oct 20, 11:06 pm, "Matt J. McCullar" <mccul...@flash.net> wrote:

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.
Click to expand...
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.
 
"Matt J. McCullar" <mccullar@flash.net> writes:

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.
Click to expand...
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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