My girlfriend has a Zenith B27A11Z TV, made in 2000, that has a
vertical deflection problem. It started as the vertical deflection
going out from time to time, and if she tapped on the TV it would come
back. So I said OK, it's probably just a bad solder joint, maybe I
can look at it sometime. But I never got around to looking at it.
Now she says that tapping it doesn't fix it anymore. Sometimes
turning it on and off does, but sometimes that doesn't work either and
if she turns it on and off too many times it stops working altogether
until she unplugs it. Now I'm wondering whether it's really a bad
joint. Of course, she still wants me to look at it. So, are there
any particular points or components that are known to go out on this
model, so that I can hopefully get this thing over with as soon as
possible?

"Jim Shaffer" wrote in message
...
My girlfriend has a Zenith B27A11Z TV, made in 2000, that has a
vertical deflection problem. It started as the vertical deflection
going out from time to time, and if she tapped on the TV it would come
back. So I said OK, it's probably just a bad solder joint, maybe I
can look at it sometime. But I never got around to looking at it.
Now she says that tapping it doesn't fix it anymore. Sometimes
turning it on and off does, but sometimes that doesn't work either and
if she turns it on and off too many times it stops working altogether
until she unplugs it. Now I'm wondering whether it's really a bad
joint. Of course, she still wants me to look at it. So, are there
any particular points or components that are known to go out on this
model, so that I can hopefully get this thing over with as soon as
possible?


Probably still solder connections - both at the vertical output IC and at
the deflection yoke plug. Should have been tended to sooner - the bad solder
connections can kill the IC, but it sounds as if the connections just got
worse since there is still full defection sometimes at turn-on.

Mark Z.

On Nov 17, 5:33*am, "Mark D. Zacharias" wrote:
"Jim Shaffer" wrote in message

...

My girlfriend has a Zenith B27A11Z TV, made in 2000, that has a
vertical deflection problem. *It started as the vertical deflection
going out from time to time, and if she tapped on the TV it would come
back. *So I said OK, it's probably just a bad solder joint, maybe I
can look at it sometime. *But I never got around to looking at it.
Now she says that tapping it doesn't fix it anymore. *Sometimes
turning it on and off does, but sometimes that doesn't work either and
if she turns it on and off too many times it stops working altogether
until she unplugs it. *Now I'm wondering whether it's really a bad
joint. *Of course, she still wants me to look at it. *So, are there
any particular points or components that are known to go out on this
model, so that I can hopefully get this thing over with as soon as
possible?

Probably still solder connections - both at the vertical output IC and at
the deflection yoke plug. Should have been tended to sooner - the bad solder
connections can kill the IC, but it sounds as if the connections just got
worse since there is still full defection sometimes at turn-on.

Mark Z.

I remember that there was a series of Zeniths a few years back in
which a diode in the vertical circuit would become flaky. It would
check good with an ohm meter as I recall but would fail
intermittently. I think it was a black high speed switching diode like
an NTE 506 about a 1 watt size near the vertical IC. Lenny. .

On 16 nov, 23:00, Jim Shaffer wrote:
My girlfriend has a Zenith B27A11Z TV, made in 2000, that has a
vertical deflection problem. It started as the vertical deflection
going out from time to time, and if she tapped on the TV it would come
back. So I said OK, it's probably just a bad solder joint, maybe I
can look at it sometime. But I never got around to looking at it.
Now she says that tapping it doesn't fix it anymore. Sometimes
turning it on and off does, but sometimes that doesn't work either and
if she turns it on and off too many times it stops working altogether
until she unplugs it. Now I'm wondering whether it's really a bad
joint. Of course, she still wants me to look at it. So, are there
any particular points or components that are known to go out on this
model, so that I can hopefully get this thing over with as soon as
possible?

this is an exact scenario which demonstrates the idea you should NEVER
nurse along an intermittent fault, the reason being that as time goes
on what starts as a simple cheap fix ends up in a complicated mess.
Chances are, other components and even the power supply have been
stressed through repeated powering up and down.
tell her to get it checked right away!
-B

Probably still solder connections - both at the vertical output IC and at
the deflection yoke plug. Should have been tended to sooner - the bad solder
connections can kill the IC, but it sounds as if the connections just got
worse since there is still full defection sometimes at turn-on.

I finally got time to work on the TV this weekend. Prodding the plug
and the vertical output chip didn't produce the symptoms. Prodding
the HOT did, but only after the set had been running for about an
hour. So I re-heated the connections, and it ran for about 3 hours
with no problems (although I didn't prod it.) Then it started acting
up again, same problem as before. (It doesn't completely lose
vertical deflection, I misunderstood what she told me; it shrinks to
about half size and jumps.) Putting pressure on the HOT's heat sink
so as to push it towards the outside of the board makes it work
properly, but only so long as pressure is maintained.

So, what do I try next? Should I have completely removed and
re-soldered the HOT? Or do I have a bad HOT since it only acts up
when it's been running for a time?

On Nov 24, 3:46 am, Jim Shaffer wrote:


So, what do I try next? Should I have completely removed and
re-soldered the HOT? Or do I have a bad HOT since it only acts up
when it's been running for a time?

a blanket resolder of the line and frame stages is called for. That
heatsink is flexing the pcb so it could be any one of dozens of joints
in that area. check also the connections to the scan coils (yoke)
As you suspected, it's best to remove old solder from the HOT and
replace, though i doubt this is your problem.
you can make a desolder braid effectively with some old 75 ohm coax
cable dipped in solder flux.

work with a good lamp and check the PCB print for any cracks.

-B

On Nov 24, 3:46 am, Jim Shaffer wrote:

re-soldered the HOT? Or do I have a bad HOT since it only acts up
when it's been running for a time?

a blanket resolder of the line and frame stages is called for. That
heatsink is flexing the pcb so it could be any one of dozens of joints
in that area. check also the connections to the scan coils (yoke)
As you suspected, it's best to remove old solder from the HOT and
replace, though i doubt this is your problem.
you can make a desolder braid effectively with some old 75 ohm coax
cable dipped in solder flux.

work with a good lamp and check the PCB print for any cracks.

-B

So, what do I try next? Should I have completely removed and
re-soldered the HOT? Or do I have a bad HOT since it only acts up
when it's been running for a time?

The HOT is the Horizontal Output Transistor. It drives the
horixontal yoke and flyback. If you are having vertical
issues... then the HOT is not the area that you should look at.

If the hot is bad.... then it would be excessively hot or blown..
If it was blown, your set wouldn't even power up...
If it was excessively hot, then it would blow before 3hrs was up....
or even sooner.
If the HOT was the problem then you'd have artifacts in the other
systems of your set, like noise in the speakers... unable to lock
onto channel... CPU malfunctions from the noise on the data lines...
perhaps causing the channels to change by themselves or spewing
jibberish onto the OSD or even killing the settings RAM chip.

Check the resistors in the vertical circuit. If they are damaged,
the that could cause the issue... especially after heating up.. and
especially for those little chip resistors on the underside of the
board. Get the data sheet for the Video Jungle chip and find the
Vertical Output pin. Replace capacitors in that circuit between the
VJ and Vertical Output. If the vertical circuit has a trimmer pot,
clean it, notice it's position and turn it left, right then back to
it's original position... Replace the capacitors in the Vertical Output
section. Wiggling the HOT headsink and creating the issue doesn't
indicate that you vertical issue is in the horizontal circuit. The
stress you put on one edge of the board will cause flexing on other
parts other than the HOT.


BTW: The collector of the HOT is usually the mounting hole for the
transistor to the heat sink.. And depending on the transistor used
and the quality of the mica insulator that might be behind transistor... that
heat sink could be holding 165+ volts or more just waiting for you to make
that one mistake of touching two places at once.

My advice is to forget the HOT if your TV is powering up and running
for 3hrs. The problem is not in the horizontal circuit. Reflowing that
circuit does nothing but waste solder and iron tip time.


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"SloppyChoppy" wrote in message
...
So, what do I try next? Should I have completely removed and
re-soldered the HOT? Or do I have a bad HOT since it only acts up
when it's been running for a time?

The HOT is the Horizontal Output Transistor. It drives the
horixontal yoke and flyback. If you are having vertical
issues... then the HOT is not the area that you should look at.

If the hot is bad.... then it would be excessively hot or blown..
If it was blown, your set wouldn't even power up...
If it was excessively hot, then it would blow before 3hrs was up....
or even sooner.
If the HOT was the problem then you'd have artifacts in the other
systems of your set, like noise in the speakers... unable to lock
onto channel... CPU malfunctions from the noise on the data lines...
perhaps causing the channels to change by themselves or spewing
jibberish onto the OSD or even killing the settings RAM chip.

Check the resistors in the vertical circuit. If they are damaged,
the that could cause the issue... especially after heating up.. and
especially for those little chip resistors on the underside of the
board. Get the data sheet for the Video Jungle chip and find the
Vertical Output pin. Replace capacitors in that circuit between the
VJ and Vertical Output. If the vertical circuit has a trimmer pot,
clean it, notice it's position and turn it left, right then back to
it's original position... Replace the capacitors in the Vertical Output
section. Wiggling the HOT headsink and creating the issue doesn't
indicate that you vertical issue is in the horizontal circuit. The
stress you put on one edge of the board will cause flexing on other
parts other than the HOT.


BTW: The collector of the HOT is usually the mounting hole for the
transistor to the heat sink.. And depending on the transistor used
and the quality of the mica insulator that might be behind transistor...
that
heat sink could be holding 165+ volts or more just waiting for you to make
that one mistake of touching two places at once.

My advice is to forget the HOT if your TV is powering up and running
for 3hrs. The problem is not in the horizontal circuit. Reflowing that
circuit does nothing but waste solder and iron tip time.


--
--------------------------------- --- -- -
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Web @ http://www.newsleecher.com/?usenet
------------------- ----- ---- -- -


I once fixed a Magnetbox with intermittent vertical tearing, turned out to
be a loose crimp on a tiny pot. Sometimes components fracture or stretch
with age, not just solder joints.

On Nov 25, 9:51*pm, "George Jetson" wrote:
"SloppyChoppy" wrote in message

...





So, what do I try next? *Should I have completely removed and
re-soldered the HOT? *Or do I have a bad HOT since it only acts up
when it's been running for a time?

The HOT is the Horizontal Output Transistor. *It drives the
horixontal yoke and flyback. *If you are having vertical
issues... then the HOT is not the area that you should look at.

If the hot is bad.... then it would be excessively hot or blown..
If it was blown, your set wouldn't even power up...
If it was excessively hot, then it would blow before 3hrs was up....
or even sooner.
If the HOT was the problem then you'd have artifacts in the other
systems of your set, like noise in the speakers... unable to lock
onto channel... *CPU malfunctions from the noise on the data lines...
perhaps causing the channels to change by themselves or spewing
jibberish onto the OSD or even killing the settings RAM chip.

Check the resistors in the vertical circuit. *If they are damaged,
the that could cause the issue... especially after heating up.. and
especially for those little chip resistors on the underside of the
board. *Get the data sheet for the Video Jungle chip and find the
Vertical Output pin. *Replace capacitors in that circuit between the
VJ and Vertical Output. *If the vertical circuit has a trimmer pot,
clean it, notice it's position and turn it left, right then back to
it's original position... Replace the capacitors in the Vertical Output
section. *Wiggling the HOT headsink and creating the issue doesn't
indicate that you vertical issue is in the horizontal circuit. *The
stress you put on one edge of the board will cause flexing on other
parts other than the HOT.

BTW: *The collector of the HOT is usually the mounting hole for the
transistor to the heat sink.. *And depending on the transistor used
and the quality of the mica insulator that might be behind *transistor...
that
heat sink could be holding 165+ volts or more just waiting for you to make
that one mistake of touching two places at once.

My advice is to forget the HOT if your TV is powering up and running
for 3hrs. *The problem is not in the horizontal circuit. Reflowing that
circuit does nothing but waste solder and iron tip time.

--
--------------------------------- --- -- -
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Web @http://www.newsleecher.com/?usenet
------------------- ----- ---- -- -

I once fixed a Magnetbox with intermittent vertical tearing, turned out to
be a loose crimp on a tiny pot. *Sometimes components fracture or stretch
with age, not just solder joints.- Hide quoted text -

- Show quoted text -

did you look for the diode? Lenny