My sony XBR is quite old (92 vintage) but still love the great picture.
Recently it developed the problem of horizontal bands of light and dark
across the entire screen which only appear in light scenes. If the picture
is dark, there are no bands and the intensity or how visible the bands are
is in direct proportion to how bright the picture is. It appears that the
bands are a distortion in the vertical sync. Thought it could be a power
supply related problem because of the sensitivity to brightness level. I do
have the service manual for the TV. Any suggestions on where to start
looking would be greatly appreciated.

Thanks in advance,
Dan

Dan wrote:
My sony XBR is quite old (92 vintage) but still love the great picture.
Recently it developed the problem of horizontal bands of light and dark
across the entire screen which only appear in light scenes. If the picture
is dark, there are no bands and the intensity or how visible the bands are
is in direct proportion to how bright the picture is. It appears that the
bands are a distortion in the vertical sync. Thought it could be a power
supply related problem because of the sensitivity to brightness level. I do
have the service manual for the TV. Any suggestions on where to start
looking would be greatly appreciated.

Thanks in advance,
Dan




Sounds like a classic case of jailbars, find the capacitor that filters
the B+ to the video amp, usually it's a 250v lytic on the neck board but
I haven't had that symptom on a Sony so it may be elsewhere.

James,
Thanks for your quick response. I should point out that the banding seems to
be a function of the horizontal scan lines being either widely separated or
closer together--you can actually see the difference in the width between
the scanning lines as opposed to normal where you can not easily see the
scan lines. That's why I thought it was associated with vertical scan signal
rather than a video problem.
Dan
"James Sweet" wrote in message
news:Hpqdf.332$9T4.210@trnddc04...
Dan wrote:
My sony XBR is quite old (92 vintage) but still love the great picture.
Recently it developed the problem of horizontal bands of light and dark
across the entire screen which only appear in light scenes. If the
picture is dark, there are no bands and the intensity or how visible the
bands are is in direct proportion to how bright the picture is. It
appears that the bands are a distortion in the vertical sync. Thought it
could be a power supply related problem because of the sensitivity to
brightness level. I do have the service manual for the TV. Any
suggestions on where to start looking would be greatly appreciated.

Thanks in advance,
Dan


Sounds like a classic case of jailbars, find the capacitor that filters
the B+ to the video amp, usually it's a 250v lytic on the neck board but I
haven't had that symptom on a Sony so it may be elsewhere.

That Model is know for many bad filter caps
and a mulitude of bad solder joints .
A heavy weight set worth fixing.

kip

"Dan" "shedlows at comcast.net" wrote in message
...
James,
Thanks for your quick response. I should point out that the banding seems
to be a function of the horizontal scan lines being either widely
separated or closer together--you can actually see the difference in the
width between the scanning lines as opposed to normal where you can not
easily see the scan lines. That's why I thought it was associated with
vertical scan signal rather than a video problem.
Dan
"James Sweet" wrote in message
news:Hpqdf.332$9T4.210@trnddc04...
Dan wrote:
My sony XBR is quite old (92 vintage) but still love the great picture.
Recently it developed the problem of horizontal bands of light and dark
across the entire screen which only appear in light scenes. If the
picture is dark, there are no bands and the intensity or how visible the
bands are is in direct proportion to how bright the picture is. It
appears that the bands are a distortion in the vertical sync. Thought it
could be a power supply related problem because of the sensitivity to
brightness level. I do have the service manual for the TV. Any
suggestions on where to start looking would be greatly appreciated.

Thanks in advance,
Dan


Sounds like a classic case of jailbars, find the capacitor that filters
the B+ to the video amp, usually it's a 250v lytic on the neck board but
I haven't had that symptom on a Sony so it may be elsewhere.

Kip
Any suggestions on which filter caps are suspect in this case? Can I test
them with a cap ESR meter that I have?

Dan
"kip" wrote in message
.. .
That Model is know for many bad filter caps
and a mulitude of bad solder joints .
A heavy weight set worth fixing.

kip

"Dan" "shedlows at comcast.net" wrote in message
...
James,
Thanks for your quick response. I should point out that the banding seems
to be a function of the horizontal scan lines being either widely
separated or closer together--you can actually see the difference in the
width between the scanning lines as opposed to normal where you can not
easily see the scan lines. That's why I thought it was associated with
vertical scan signal rather than a video problem.
Dan
"James Sweet" wrote in message
news:Hpqdf.332$9T4.210@trnddc04...
Dan wrote:
My sony XBR is quite old (92 vintage) but still love the great picture.
Recently it developed the problem of horizontal bands of light and dark
across the entire screen which only appear in light scenes. If the
picture is dark, there are no bands and the intensity or how visible
the bands are is in direct proportion to how bright the picture is. It
appears that the bands are a distortion in the vertical sync. Thought
it could be a power supply related problem because of the sensitivity
to brightness level. I do have the service manual for the TV. Any
suggestions on where to start looking would be greatly appreciated.

Thanks in advance,
Dan


Sounds like a classic case of jailbars, find the capacitor that filters
the B+ to the video amp, usually it's a 250v lytic on the neck board but
I haven't had that symptom on a Sony so it may be elsewhere.

Yes use the ESR meter...also look for swollen caps
in the power sections and around the flyback area.
Caps are cheap ....Go to it.
kip
"Dan" "shedlows at comcast.net" wrote in message
...
Kip
Any suggestions on which filter caps are suspect in this case? Can I test
them with a cap ESR meter that I have?

Dan
"kip" wrote in message
.. .
That Model is know for many bad filter caps
and a mulitude of bad solder joints .
A heavy weight set worth fixing.

kip

"Dan" "shedlows at comcast.net" wrote in message
...
James,
Thanks for your quick response. I should point out that the banding
seems to be a function of the horizontal scan lines being either widely
separated or closer together--you can actually see the difference in the
width between the scanning lines as opposed to normal where you can not
easily see the scan lines. That's why I thought it was associated with
vertical scan signal rather than a video problem.
Dan
"James Sweet" wrote in message
news:Hpqdf.332$9T4.210@trnddc04...
Dan wrote:
My sony XBR is quite old (92 vintage) but still love the great
picture. Recently it developed the problem of horizontal bands of
light and dark across the entire screen which only appear in light
scenes. If the picture is dark, there are no bands and the intensity
or how visible the bands are is in direct proportion to how bright the
picture is. It appears that the bands are a distortion in the vertical
sync. Thought it could be a power supply related problem because of
the sensitivity to brightness level. I do have the service manual for
the TV. Any suggestions on where to start looking would be greatly
appreciated.

Thanks in advance,
Dan


Sounds like a classic case of jailbars, find the capacitor that filters
the B+ to the video amp, usually it's a 250v lytic on the neck board
but I haven't had that symptom on a Sony so it may be elsewhere.

May just be bad solder at the vertical IC. Sky.


"Dan" "shedlows at comcast.net" wrote in message
...
My sony XBR is quite old (92 vintage) but still love the great picture.
Recently it developed the problem of horizontal bands of light and dark
across the entire screen which only appear in light scenes. If the picture
is dark, there are no bands and the intensity or how visible the bands are
is in direct proportion to how bright the picture is. It appears that the
bands are a distortion in the vertical sync. Thought it could be a power
supply related problem because of the sensitivity to brightness level. I
do have the service manual for the TV. Any suggestions on where to start
looking would be greatly appreciated.

Thanks in advance,
Dan

Thanks for all of your suggestions--will have at it and let you know how I
make out
"Skype_man" wrote in message
.. .
May just be bad solder at the vertical IC. Sky.


"Dan" "shedlows at comcast.net" wrote in message
...
My sony XBR is quite old (92 vintage) but still love the great picture.
Recently it developed the problem of horizontal bands of light and dark
across the entire screen which only appear in light scenes. If the
picture is dark, there are no bands and the intensity or how visible the
bands are is in direct proportion to how bright the picture is. It
appears that the bands are a distortion in the vertical sync. Thought it
could be a power supply related problem because of the sensitivity to
brightness level. I do have the service manual for the TV. Any
suggestions on where to start looking would be greatly appreciated.

Thanks in advance,
Dan

Thanks for all of your suggestions--will have at it and let you know how I
make out
"Skype_man" wrote in message
.. .
May just be bad solder at the vertical IC. Sky.


"Dan" "shedlows at comcast.net" wrote in message
...
My sony XBR is quite old (92 vintage) but still love the great picture.
Recently it developed the problem of horizontal bands of light and dark
across the entire screen which only appear in light scenes. If the
picture is dark, there are no bands and the intensity or how visible the
bands are is in direct proportion to how bright the picture is. It
appears that the bands are a distortion in the vertical sync. Thought it
could be a power supply related problem because of the sensitivity to
brightness level. I do have the service manual for the TV. Any
suggestions on where to start looking would be greatly appreciated.

Thanks in advance,
Dan

One last question--TV must have heard that I was about to repair it--is now
working fine. The symptoms normally started a short time after warming up
but then sometimes disappeared. Today no symptoms. Question--is this more
likely a poor solder connection than a bad filter cap. Thought once a cap
went bad it would stay bad.
"Dan" "shedlows at comcast.net" wrote in message
...
Thanks for all of your suggestions--will have at it and let you know how I
make out
"Skype_man" wrote in message
.. .
May just be bad solder at the vertical IC. Sky.


"Dan" "shedlows at comcast.net" wrote in message
...
My sony XBR is quite old (92 vintage) but still love the great picture.
Recently it developed the problem of horizontal bands of light and dark
across the entire screen which only appear in light scenes. If the
picture is dark, there are no bands and the intensity or how visible the
bands are is in direct proportion to how bright the picture is. It
appears that the bands are a distortion in the vertical sync. Thought it
could be a power supply related problem because of the sensitivity to
brightness level. I do have the service manual for the TV. Any
suggestions on where to start looking would be greatly appreciated.

Thanks in advance,
Dan

Once a cap goes bad it stays bad?
If a capacitor is marginal, in other words just barely outside of
tolerance for ESR and in process of drying out, the temperature will
affect how the capacitor acts in circuit. It is not uncommon for it to
appear to work when it is warmed up when it is just outside of
specification.

That being said, your specific symptom is more than likely solder
connection related. The set will need carefully inspected for bad
solder connections to all the low voltage regulators, the vertical ic,
along with potential solder problems inside the tuner and IF can.

No, lytics heal sorta when the temp goes up. Many sets in the shop need
a cooldown before we can see a symptom.

If you are indeed seeing rarifications in the scan lines head for the
vertical, and if included, the N-S pincushion ckt or the dynamic
convergence circuit. Of course you are still looking for electrolytics,
most likely.

JURB

Actually my symptoms only appear when temp goes up. Always start after set
is on for some time and then may disappear after a time. Never appear when
set is first turned on.

For the past 2 days, no symptoms, even after extended operation but I have
not done anything to fix it.

Once again, thanks for all of your helpful responses. I'm a newbie on this
list and it is the most responsive and helpful list I have ever posted to.

wrote in message
ups.com...
No, lytics heal sorta when the temp goes up. Many sets in the shop need
a cooldown before we can see a symptom.

If you are indeed seeing rarifications in the scan lines head for the
vertical, and if included, the N-S pincushion ckt or the dynamic
convergence circuit. Of course you are still looking for electrolytics,
most likely.

JURB