Problem with Sony KV-T25SZ8 TV when turning on
 

This television displays a strange image and sound distortion just after
it's been turned on, as shown in this 5 second video.

http://www.youtube.com/watch?v=usQFxTJ04s4

It may do this several times, and, rather disconcertingly, seems to be
slowly getting worse.

Note - the slight flickering is an artefact of the video recording.

I'm using a computer output to show the fault, but I get the same
behaviour on broadcast channels if the computer is completely
disconnected, and turned off.

I suspect a warming up effect. Any ideas?

Sylvia.

Problem with Sony KV-T25SZ8 TV when turning on
 

Sylvia Else wrote:

This television displays a strange image and sound distortion just after
it's been turned on, as shown in this 5 second video.

http://www.youtube.com/watch?v=usQFxTJ04s4

It may do this several times, and, rather disconcertingly, seems to be
slowly getting worse.

Note - the slight flickering is an artefact of the video recording.

I'm using a computer output to show the fault, but I get the same
behaviour on broadcast channels if the computer is completely
disconnected, and turned off.

I suspect a warming up effect. Any ideas?

Sylvia.
Yup, that's High Voltage arcing around in there.

Might me a good idea to have some one that knows more
about it to take a look.

Problem with Sony KV-T25SZ8 TV when turning on
 

Jamie wrote:
Sylvia Else wrote:

This television displays a strange image and sound distortion just
after it's been turned on, as shown in this 5 second video.

http://www.youtube.com/watch?v=usQFxTJ04s4

It may do this several times, and, rather disconcertingly, seems to be
slowly getting worse.

Note - the slight flickering is an artefact of the video recording.

I'm using a computer output to show the fault, but I get the same
behaviour on broadcast channels if the computer is completely
disconnected, and turned off.

I suspect a warming up effect. Any ideas?

Sylvia.
Yup, that's High Voltage arcing around in there.

Ouch!

Might me a good idea to have some one that knows more
about it to take a look.


I've disconnected it from the mains. Later on today (to allow any caps
to discharge) I'll take the back off and see whether there's any obvious
reason for arcing - dead insects, loose connections.

Beyond that, I have the problem of deciding whether it's worth paying to
repair a 10 year old CRT TV :(

Sylvia.

Problem with Sony KV-T25SZ8 TV when turning on
 

Jamie wrote:
Sylvia Else wrote:

Jamie wrote:

Sylvia Else wrote:

This television displays a strange image and sound distortion just
after it's been turned on, as shown in this 5 second video.

http://www.youtube.com/watch?v=usQFxTJ04s4

It may do this several times, and, rather disconcertingly, seems to
be slowly getting worse.

Note - the slight flickering is an artefact of the video recording.

I'm using a computer output to show the fault, but I get the same
behaviour on broadcast channels if the computer is completely
disconnected, and turned off.

I suspect a warming up effect. Any ideas?

Sylvia.

Yup, that's High Voltage arcing around in there.


Ouch!


Might me a good idea to have some one that knows more
about it to take a look.


I've disconnected it from the mains. Later on today (to allow any caps
to discharge) I'll take the back off and see whether there's any
obvious reason for arcing - dead insects, loose connections.

Beyond that, I have the problem of deciding whether it's worth paying
to repair a 10 year old CRT TV :(

Sylvia.
It's not worth having it fixed in my opinion..

If you can't correct the problem via a clean out, I suggest you start
looking for a LCD unit.

That would be my thought exactly.

Sylvia.

Problem with Sony KV-T25SZ8 TV when turning on
 

Sylvia Else wrote:

Jamie wrote:

Sylvia Else wrote:

This television displays a strange image and sound distortion just
after it's been turned on, as shown in this 5 second video.

http://www.youtube.com/watch?v=usQFxTJ04s4

It may do this several times, and, rather disconcertingly, seems to
be slowly getting worse.

Note - the slight flickering is an artefact of the video recording.

I'm using a computer output to show the fault, but I get the same
behaviour on broadcast channels if the computer is completely
disconnected, and turned off.

I suspect a warming up effect. Any ideas?

Sylvia.

Yup, that's High Voltage arcing around in there.


Ouch!


Might me a good idea to have some one that knows more
about it to take a look.


I've disconnected it from the mains. Later on today (to allow any caps
to discharge) I'll take the back off and see whether there's any obvious
reason for arcing - dead insects, loose connections.

Beyond that, I have the problem of deciding whether it's worth paying to
repair a 10 year old CRT TV :(

Sylvia.
It's not worth having it fixed in my opinion..

If you can't correct the problem via a clean out, I suggest you start
looking for a LCD unit.

Problem with Sony KV-T25SZ8 TV when turning on
 

Sylvia Else wrote:
This television displays a strange image and sound distortion just after
it's been turned on, as shown in this 5 second video.

http://www.youtube.com/watch?v=usQFxTJ04s4

It may do this several times, and, rather disconcertingly, seems to be
slowly getting worse.

Note - the slight flickering is an artefact of the video recording.

I'm using a computer output to show the fault, but I get the same
behaviour on broadcast channels if the computer is completely
disconnected, and turned off.

I suspect a warming up effect. Any ideas?

Sylvia.

Affects picture contents, colour and sound; could be a supply voltage.
Maybe check the PSU for bulging caps.

Tony

Problem with Sony KV-T25SZ8 TV when turning on
 

Meat Plow wrote:
On Mon, 10 Aug 2009 11:32:24 +1000, Sylvia Else
wrote:

Jamie wrote:
Sylvia Else wrote:

This television displays a strange image and sound distortion just
after it's been turned on, as shown in this 5 second video.

http://www.youtube.com/watch?v=usQFxTJ04s4

It may do this several times, and, rather disconcertingly, seems to be
slowly getting worse.

Note - the slight flickering is an artefact of the video recording.

I'm using a computer output to show the fault, but I get the same
behaviour on broadcast channels if the computer is completely
disconnected, and turned off.

I suspect a warming up effect. Any ideas?

Sylvia.
Yup, that's High Voltage arcing around in there.
Ouch!
Might me a good idea to have some one that knows more
about it to take a look.

I've disconnected it from the mains. Later on today (to allow any caps
to discharge) I'll take the back off and see whether there's any obvious
reason for arcing - dead insects, loose connections.

Beyond that, I have the problem of deciding whether it's worth paying to
repair a 10 year old CRT TV :(

Sylvia.

Remember the CRT can store a nasty zap. It might be an easy fix by
cleaning off the HV components. Over time to build up on HV parts I've
seen airborne contaminants cause arcs. But again watch the anode
connection on the CRT.

It would help if I could see where it was arcing, but like all good
intermittent faults, it only seems to happen when no one's looking at
the circuitry. I've given it a general clean out. We'll see....

Sylvia.

Problem with Sony KV-T25SZ8 TV when turning on
 

Sylvia Else wrote:
Jamie wrote:
Sylvia Else wrote:

This television displays a strange image and sound distortion just
after it's been turned on, as shown in this 5 second video.

http://www.youtube.com/watch?v=usQFxTJ04s4

It may do this several times, and, rather disconcertingly, seems to
be slowly getting worse.

Note - the slight flickering is an artefact of the video recording.

I'm using a computer output to show the fault, but I get the same
behaviour on broadcast channels if the computer is completely
disconnected, and turned off.

I suspect a warming up effect. Any ideas?

Sylvia.
Yup, that's High Voltage arcing around in there.

Ouch!

Might me a good idea to have some one that knows more
about it to take a look.


I've disconnected it from the mains. Later on today (to allow any caps
to discharge) I'll take the back off and see whether there's any obvious
reason for arcing - dead insects, loose connections.

Accumulated dust &/or smoke on the EHT circuitry & the back of the CRT.
Take the back off the TV & see if you can see any arcing.

Beyond that, I have the problem of deciding whether it's worth paying to
repair a 10 year old CRT TV :(

I would. It most likely needs nothing more than cleaning out all the gunk.

--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------

Problem with Sony KV-T25SZ8 TV when turning on
 

Bob Larter wrote:
Sylvia Else wrote:

Accumulated dust &/or smoke on the EHT circuitry & the back of the CRT.
Take the back off the TV & see if you can see any arcing.


I would. It most likely needs nothing more than cleaning out all the gunk.


It's been a long time since I fixed my CRT TVs. But, wasn't it that the picture
expanded when the HV briefly collapsed when arcing? I can't see this happening
in the video.

Tony

Problem with Sony KV-T25SZ8 TV when turning on
 

TonyS wrote:
Bob Larter wrote:
Sylvia Else wrote:

Accumulated dust &/or smoke on the EHT circuitry & the back of the
CRT. Take the back off the TV & see if you can see any arcing.


I would. It most likely needs nothing more than cleaning out all the
gunk.


It's been a long time since I fixed my CRT TVs. But, wasn't it that the
picture expanded when the HV briefly collapsed when arcing? I can't see
this happening in the video.

I would expect the image to shrink horizontally &/or lose brightness
during arcing.

--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------

Problem with Sony KV-T25SZ8 TV when turning on
 

Bob Larter wrote:
TonyS wrote:
Bob Larter wrote:
Sylvia Else wrote:

Accumulated dust &/or smoke on the EHT circuitry & the back of the
CRT. Take the back off the TV & see if you can see any arcing.


I would. It most likely needs nothing more than cleaning out all the
gunk.


It's been a long time since I fixed my CRT TVs. But, wasn't it that
the picture expanded when the HV briefly collapsed when arcing? I
can't see this happening in the video.

I would expect the image to shrink horizontally &/or lose brightness
during arcing.


I think there is an, albeit slight, reduction in width. Whether the
brightness drops is hard to say because the colour disappears.

What I find striking is that some scan lines appear to start early, by
an amount of time that is quite consistent.

It's not clear to me whether the noise is coming out of the
loudspeakers, or directly from the interior of the TV.

Sylvia.

Problem with Sony KV-T25SZ8 TV when turning on
 

"Sylvia Else" wrote in message
...
Bob Larter wrote:
TonyS wrote:
Bob Larter wrote:
Sylvia Else wrote:

Accumulated dust &/or smoke on the EHT circuitry & the back of the CRT.
Take the back off the TV & see if you can see any arcing.


I would. It most likely needs nothing more than cleaning out all the
gunk.


It's been a long time since I fixed my CRT TVs. But, wasn't it that the
picture expanded when the HV briefly collapsed when arcing? I can't see
this happening in the video.

I would expect the image to shrink horizontally &/or lose brightness
during arcing.


I think there is an, albeit slight, reduction in width. Whether the
brightness drops is hard to say because the colour disappears.

What I find striking is that some scan lines appear to start early, by an
amount of time that is quite consistent.

It's not clear to me whether the noise is coming out of the loudspeakers,
or directly from the interior of the TV.

Sylvia.


Over the years many Sony sets have had an issue with bad solder connections
at the horizontal drive transformer and related parts - the drive
transistor, resistors, etc. A soon-to-be-failing horizontal circuit might
exhibit your symptoms.

Mark Z.

Problem with Sony KV-T25SZ8 TV when turning on
 

Sylvia Else wrote:
Bob Larter wrote:
TonyS wrote:
Bob Larter wrote:
Sylvia Else wrote:

Accumulated dust &/or smoke on the EHT circuitry & the back of the
CRT. Take the back off the TV & see if you can see any arcing.


I would. It most likely needs nothing more than cleaning out all the
gunk.


It's been a long time since I fixed my CRT TVs. But, wasn't it that
the picture expanded when the HV briefly collapsed when arcing? I
can't see this happening in the video.

I would expect the image to shrink horizontally &/or lose brightness
during arcing.


I think there is an, albeit slight, reduction in width. Whether the
brightness drops is hard to say because the colour disappears.

What I find striking is that some scan lines appear to start early, by
an amount of time that is quite consistent.

It's not clear to me whether the noise is coming out of the
loudspeakers, or directly from the interior of the TV.

Try muting the sound then listen for the noises. If it's audible at all,
arcing tends to make a hissing or crackling noise.

--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------

Problem with Sony KV-T25SZ8 TV when turning on
 

Bob Larter wrote:
Sylvia Else wrote:
Bob Larter wrote:
TonyS wrote:
Bob Larter wrote:
Sylvia Else wrote:

Accumulated dust &/or smoke on the EHT circuitry & the back of the
CRT. Take the back off the TV & see if you can see any arcing.


I would. It most likely needs nothing more than cleaning out all
the gunk.


It's been a long time since I fixed my CRT TVs. But, wasn't it that
the picture expanded when the HV briefly collapsed when arcing? I
can't see this happening in the video.

I would expect the image to shrink horizontally &/or lose brightness
during arcing.


I think there is an, albeit slight, reduction in width. Whether the
brightness drops is hard to say because the colour disappears.

What I find striking is that some scan lines appear to start early, by
an amount of time that is quite consistent.

It's not clear to me whether the noise is coming out of the
loudspeakers, or directly from the interior of the TV.

Try muting the sound then listen for the noises. If it's audible at all,
arcing tends to make a hissing or crackling noise.


Does muting kill the power to the audio output amplifier, or just its
audio input?

Sylvia.

Problem with Sony KV-T25SZ8 TV when turning on
 

On 10 ago, 02:57, Sylvia Else wrote:
This television displays a strange image and sound distortion just after
it's been turned on, as shown in this 5 second video.

http://www.youtube.com/watch?v=usQFxTJ04s4

It may do this several times, and, rather disconcertingly, seems to be
slowly getting worse.

As others have said, open it up and clean the area near the crt
suction cup. Look under the main pcb at the print side for cracked
solder joints (may have to disconnect some cables - take a picture to
remember) especially in the area near the large transformer. it is a
waste to send it to landfill without at least checking these common
things.

-B

Problem with Sony KV-T25SZ8 TV when turning on
 

"Sylvia Else" wrote in message
...
Bob Larter wrote:
Sylvia Else wrote:
Bob Larter wrote:
TonyS wrote:
Bob Larter wrote:
Sylvia Else wrote:

Accumulated dust &/or smoke on the EHT circuitry & the back of the
CRT. Take the back off the TV & see if you can see any arcing.


I would. It most likely needs nothing more than cleaning out all the
gunk.


It's been a long time since I fixed my CRT TVs. But, wasn't it that
the picture expanded when the HV briefly collapsed when arcing? I
can't see this happening in the video.

I would expect the image to shrink horizontally &/or lose brightness
during arcing.


I think there is an, albeit slight, reduction in width. Whether the
brightness drops is hard to say because the colour disappears.

What I find striking is that some scan lines appear to start early, by
an amount of time that is quite consistent.

It's not clear to me whether the noise is coming out of the
loudspeakers, or directly from the interior of the TV.

Try muting the sound then listen for the noises. If it's audible at all,
arcing tends to make a hissing or crackling noise.


Does muting kill the power to the audio output amplifier, or just its
audio input?

Sylvia.


He meant to listen to whether any sound could be heard from inside the
cabinet, with the volume down (or muted), not from the speakers.

To answer your question, muting is usually accomplished by means of a
transistor placed across the input of the audio amp circuit. When turned ON,
the transistor essentially shorts the input of the amp to ground. Sometimes
a relay is used at the output of the audio amp to open the amp from the
speaker load, although I haven't seen this done on televisions, only on
larger audio amps.

Mark Z.

Problem with Sony KV-T25SZ8 TV when turning on
 

"Meat Plow" wrote in message
...
On Mon, 17 Aug 2009 06:18:32 -0500, "Mark Zacharias"
wrote:

"Sylvia Else" wrote in message
.. .
Bob Larter wrote:
Sylvia Else wrote:
Bob Larter wrote:
TonyS wrote:
Bob Larter wrote:
Sylvia Else wrote:

Accumulated dust &/or smoke on the EHT circuitry & the back of the
CRT. Take the back off the TV & see if you can see any arcing.


I would. It most likely needs nothing more than cleaning out all
the
gunk.


It's been a long time since I fixed my CRT TVs. But, wasn't it that
the picture expanded when the HV briefly collapsed when arcing? I
can't see this happening in the video.

I would expect the image to shrink horizontally &/or lose brightness
during arcing.


I think there is an, albeit slight, reduction in width. Whether the
brightness drops is hard to say because the colour disappears.

What I find striking is that some scan lines appear to start early, by
an amount of time that is quite consistent.

It's not clear to me whether the noise is coming out of the
loudspeakers, or directly from the interior of the TV.

Try muting the sound then listen for the noises. If it's audible at
all,
arcing tends to make a hissing or crackling noise.


Does muting kill the power to the audio output amplifier, or just its
audio input?

Sylvia.


He meant to listen to whether any sound could be heard from inside the
cabinet, with the volume down (or muted), not from the speakers.

To answer your question, muting is usually accomplished by means of a
transistor placed across the input of the audio amp circuit. When turned
ON,
the transistor essentially shorts the input of the amp to ground.
Sometimes
a relay is used at the output of the audio amp to open the amp from the
speaker load, although I haven't seen this done on televisions, only on
larger audio amps.

Mark Z.

Isn't lifting the load from a high power audio amp asking for trouble?


Not for a solid state amp. Besides, we're talking about a television audio
amp IC. Hardly high power. Virtually every audio amp or receiver over 40
watts per channel made since around 1970 uses one or more relays to control
the output or protect the speakers in the event of a malfunction.

Mark Z.

Problem with Sony KV-T25SZ8 TV when turning on
 

Sylvia Else wrote:
Bob Larter wrote:
Sylvia Else wrote:
Bob Larter wrote:
TonyS wrote:
Bob Larter wrote:
Sylvia Else wrote:

Accumulated dust &/or smoke on the EHT circuitry & the back of the
CRT. Take the back off the TV & see if you can see any arcing.


I would. It most likely needs nothing more than cleaning out all
the gunk.


It's been a long time since I fixed my CRT TVs. But, wasn't it that
the picture expanded when the HV briefly collapsed when arcing? I
can't see this happening in the video.

I would expect the image to shrink horizontally &/or lose brightness
during arcing.


I think there is an, albeit slight, reduction in width. Whether the
brightness drops is hard to say because the colour disappears.

What I find striking is that some scan lines appear to start early,
by an amount of time that is quite consistent.

It's not clear to me whether the noise is coming out of the
loudspeakers, or directly from the interior of the TV.

Try muting the sound then listen for the noises. If it's audible at
all, arcing tends to make a hissing or crackling noise.


Does muting kill the power to the audio output amplifier, or just its
audio input?

Dunno, but most probably the latter.

--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------

Problem with Sony KV-T25SZ8 TV when turning on
 

Sylvia Else wrote:
This television displays a strange image and sound distortion just after
it's been turned on, as shown in this 5 second video.

http://www.youtube.com/watch?v=usQFxTJ04s4

It may do this several times, and, rather disconcertingly, seems to be
slowly getting worse.

Note - the slight flickering is an artefact of the video recording.

I'm using a computer output to show the fault, but I get the same
behaviour on broadcast channels if the computer is completely
disconnected, and turned off.

I suspect a warming up effect. Any ideas?

Sylvia.

Just a followup on this. The problem got gradually worse, to the point
where it continued for minutes after turn on.

Which gave me a chance to see where it was arcing. Turned out to be
underneath the circuit board, due to a fractured solder joint, and hence
only visible when I had the back of and bent down to see that area. Once
I knew where to look, it was obvious that the joint was broken. 30
second soldering job, and now it's good as new.

The surprise is more that it was working at all.

Special thanks to Jamie for the correct diagnosis of arcing.

Sylvia.

Problem with Sony KV-T25SZ8 TV when turning on
 

Sylvia Else wrote:
and now it's good as new.

I may have spoken too soon. Certainly the arcing issue is resolved.

But now the picture colours make it looks as if the tube is in need of a
serious degaussing. Even the television's own set up captions vary in
colour across the screen.

If I understand things correctly, this cannot be a consequence of my
soldering technique, but has to be the result of something moving when I
tilted the TV over to get access to the circuit board.

Either that, or there is previously unnoticed mucking great magnet
underneath my floor boards.

Any thoughts?

Sylvia.

Problem with Sony KV-T25SZ8 TV when turning on
 

Sylvia Else wrote:
Sylvia Else wrote:
and now it's good as new.

I may have spoken too soon. Certainly the arcing issue is resolved.

But now the picture colours make it looks as if the tube is in need of a
serious degaussing. Even the television's own set up captions vary in
colour across the screen.

If I understand things correctly, this cannot be a consequence of my
soldering technique, but has to be the result of something moving when I
tilted the TV over to get access to the circuit board.

Either that, or there is previously unnoticed mucking great magnet
underneath my floor boards.

Any thoughts?

Sylvia.



So I pulled it apart again, checked for anything loose in the stuff
attached the tube - there wasn't - and put it back together...

.... and it's fine.

While I was getting a handle on where exactly it was arcing, I was
running it screen face down (on a soft surface), for a while, so the
Earth's magnetic field would certainly have changed relative position.

Could it be that all it needed was a couple more cycles of its own
degaussing?

I'm pleased that it's OK, but I don't like not knowing why.

Sylvia.

Problem with Sony KV-T25SZ8 TV when turning on
 

Could it be that all it needed was a couple more cycles
of its own degaussing?

Likely. It also might be that the shadow mask got warped, and repeated
handling knocked it back into shape.

Problem with Sony KV-T25SZ8 TV when turning on
 

William Sommerwerck wrote:
Could it be that all it needed was a couple more cycles
of its own degaussing?

Likely. It also might be that the shadow mask got warped, and repeated
handling knocked it back into shape.



Just for the record, and for the benefit of anyone who comes across this
in the archive, further online research revealed that part of the
purpose of the degaussing process is to *magnetise* the shadow mask in
such a way as to cancel out the Earth's magnetic field in the space
between the mask and the screen. This is the reason the shadow mask is
made of a magnetisable material (which otherwise would seem a strange
design choice).

So my experience can be adequately explained by the fact that I powered
the TV up while it was in a completely different orientation from
normal. It was then entirely possible that this would take several
degaussing cycles to undo properly once I had the TV back in the normal
position. The situation was further confused by my failure to realise
that this model only degausses when powered up from the mains, and not
when going from standby to on. It's necessary to power it down
completely for a while before powering it up again for it to do its
degaussing.

So I guess that's that.

Sylvia.

Problem with Sony KV-T25SZ8 TV when turning on
 

Sylvia Else wrote:

William Sommerwerck wrote:
Could it be that all it needed was a couple more cycles
of its own degaussing?

Likely. It also might be that the shadow mask got warped, and
repeated handling knocked it back into shape.



Just for the record, and for the benefit of anyone who comes across
this in the archive, further online research revealed that part of the
purpose of the degaussing process is to *magnetise* the shadow mask in
such a way as to cancel out the Earth's magnetic field in the space
between the mask and the screen. This is the reason the shadow mask is
made of a magnetisable material (which otherwise would seem a strange
design choice).

So my experience can be adequately explained by the fact that I
powered the TV up while it was in a completely different orientation
from normal. It was then entirely possible that this would take
several degaussing cycles to undo properly once I had the TV back in
the normal position. The situation was further confused by my failure
to realise that this model only degausses when powered up from the
mains, and not when going from standby to on. It's necessary to power
it down completely for a while before powering it up again for it to
do its degaussing.

So I guess that's that.

Sylvia.

Its also why many have a manual degauss button or menu selection.

--
Best Regards:
Baron.