Problem with Sony KV-T25SZ8 TV when turning on

[Sylvia Else]

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.

 

[Jamie]

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.

 

[Sylvia Else]

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.

 

[Sylvia Else]

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.

 

[Jamie]

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.

 

[TonyS]

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

 

[Meat Plow]

On Mon, 10 Aug 2009 11:32:24 +1000, Sylvia Else
<sylvia@not.at.this.address>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.

 

[Sylvia Else]

Meat Plow wrote:

On Mon, 10 Aug 2009 11:32:24 +1000, Sylvia Else
sylvia@not.at.this.address>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.

 

[Meat Plow]

On Tue, 11 Aug 2009 11:57:52 +1000, Sylvia Else
<sylvia@not.at.this.address>wrote:

Meat Plow wrote:
On Mon, 10 Aug 2009 11:32:24 +1000, Sylvia Else
sylvia@not.at.this.address>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.

Yeah been there done that. A good wipe down with 91% Isopropyl goes a
long way. Watch the anode.

 

[Bob Larter]

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
---^----^---------------------------------------------------------------

 

[TonyS]

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

 

[Bob Larter]

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
---^----^---------------------------------------------------------------

 

[Sylvia Else]

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.

 

[Mark Zacharias]

"Sylvia Else" <sylvia@not.at.this.address> wrote in message
news:00caaccd$0$3654$c3e8da3@news.astraweb.com...

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.

 

[Bob Larter]

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
---^----^---------------------------------------------------------------

 

[Sylvia Else]

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.

 

[Mark Zacharias]

"Sylvia Else" <sylvia@not.at.this.address> wrote in message
news:00049d62$0$7861$c3e8da3@news.astraweb.com...

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.

 

[b]

On 10 ago, 02:57, Sylvia Else <syl...@not.at.this.address> 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

 

[Meat Plow]

On Mon, 17 Aug 2009 06:18:32 -0500, "Mark Zacharias"
<mark_zacharias@sbclobal.net>wrote:

"Sylvia Else" <sylvia@not.at.this.address> wrote in message
news:00049d62$0$7861$c3e8da3@news.astraweb.com...
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?

 

[Mark Zacharias]

"Meat Plow" <meat@petitmorte.net> wrote in message
news:328c2j.2m2.19.3@news.alt.net...

On Mon, 17 Aug 2009 06:18:32 -0500, "Mark Zacharias"
mark_zacharias@sbclobal.net>wrote:

"Sylvia Else" <sylvia@not.at.this.address> wrote in message
news:00049d62$0$7861$c3e8da3@news.astraweb.com...
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.