Hello,
I'm trying to diagnose a fault that just developed,
I get sound, and I can feel/here the static electricy
that's generated on the screen when it's turned on.
The screen remains black.

I took the back off the TV and I can see that all
of the neck filamants are unlit.

Please advise. This is a 1992 Sony 27 inch XBR
(kv27-xbr35) Thanks for any assistance.

Dave

"davexnet02" wrote in message
...
Hello,
I'm trying to diagnose a fault that just developed,
I get sound, and I can feel/here the static electricy
that's generated on the screen when it's turned on.
The screen remains black.

I took the back off the TV and I can see that all
of the neck filamants are unlit.

Please advise. This is a 1992 Sony 27 inch XBR
(kv27-xbr35) Thanks for any assistance.

Dave

Dry joint, heater supply off the line ouput transformer?

David

On Tue, 14 Dec 2004 19:58:27 -0000, "David Sewell"
wrote:


"davexnet02" wrote in message
.. .
Hello,
I'm trying to diagnose a fault that just developed,
I get sound, and I can feel/here the static electricy
that's generated on the screen when it's turned on.
The screen remains black.

I took the back off the TV and I can see that all
of the neck filamants are unlit.

Please advise. This is a 1992 Sony 27 inch XBR
(kv27-xbr35) Thanks for any assistance.

Dave

Dry joint, heater supply off the line ouput transformer?

David

LOPT = flyback?
There's the thick wire that goes to the anode,
and a thinner wire that goes to the small circuit board
at the back of the tube. Is that the heater?
I thought it was the focus.

Dave

Loss of +200 VDC to the video driver/output. Defective Video driver/output.
Defective CRT, Etc Post the diagnostic measurements you have actually made
so we may asset what you have done already then render assistance.
"davexnet02" wrote in message
...
On Tue, 14 Dec 2004 19:58:27 -0000, "David Sewell"
wrote:


"davexnet02" wrote in message
. ..
Hello,
I'm trying to diagnose a fault that just developed,
I get sound, and I can feel/here the static electricy
that's generated on the screen when it's turned on.
The screen remains black.

I took the back off the TV and I can see that all
of the neck filamants are unlit.

Please advise. This is a 1992 Sony 27 inch XBR
(kv27-xbr35) Thanks for any assistance.

Dave

Dry joint, heater supply off the line ouput transformer?

David

LOPT = flyback?
There's the thick wire that goes to the anode,
and a thinner wire that goes to the small circuit board
at the back of the tube. Is that the heater?
I thought it was the focus.

Dave

On Tue, 14 Dec 2004 15:58:17 -0500, "Art"
wrote:

Loss of +200 VDC to the video driver/output. Defective Video driver/output.
Defective CRT, Etc Post the diagnostic measurements you have actually made
so we may asset what you have done already then render assistance.
Hi Art, thanks for responding.
Alas, I have not made any "diagnostic measurements", just some
observations. I am not a qualified TV servicer, but I do have some
electronics background, and I have a copy of the service manual.

I have not done anything except resolder all the pins on the
power supply board transformers. (Sony G board).
Problem remains.

Perhaps the TV has reached the end of it's useful life,
or at least it's cost effective life.

Dave

On Tue, 14 Dec 2004 18:47:23 GMT, davexnet02
wrote:

Hello,
I'm trying to diagnose a fault that just developed,
I get sound, and I can feel/here the static electricy
that's generated on the screen when it's turned on.
The screen remains black.

If the red LED flashes, the set may be in IK blanking. Try turning the
screen control up slightly. If the picture comes in, it *could*
indicate a weak CRT. However, we had a Sony KV27EX25 in the shop today
that had no raster. Turning up the screen restored the pix, which is
often associated with a weak picture tube. But the CRT on this set
checked good. Further checking showed a low screen (G2) voltage. We
found an open 1 meg resistor on the CRT board in series with the
screen control. Replacing the resistor restored an excellent picture.

Alan Harriman




I took the back off the TV and I can see that all
of the neck filamants are unlit.

Please advise. This is a 1992 Sony 27 inch XBR
(kv27-xbr35) Thanks for any assistance.

Dave

On Wed, 15 Dec 2004 04:16:15 GMT, Alan Harriman
wrote:

On Tue, 14 Dec 2004 18:47:23 GMT, davexnet02
wrote:

Hello,
I'm trying to diagnose a fault that just developed,
I get sound, and I can feel/here the static electricy
that's generated on the screen when it's turned on.
The screen remains black.

If the red LED flashes, the set may be in IK blanking. Try turning the
screen control up slightly. If the picture comes in, it *could*
indicate a weak CRT. However, we had a Sony KV27EX25 in the shop today
that had no raster. Turning up the screen restored the pix, which is
often associated with a weak picture tube. But the CRT on this set
checked good. Further checking showed a low screen (G2) voltage. We
found an open 1 meg resistor on the CRT board in series with the
screen control. Replacing the resistor restored an excellent picture.

Alan Harriman
Hi Alan, never seen a flashing LED on this set.
Was that implemented in the 1992 models?

I had suspicions about a weak CRT prior to this failure.
The grey scale was off (too blue) and it was satrting to wash out.

As I mentioned, the CRT filaments are not lit at all.
I'll check the CRT board to see if anything shows up there.
Thanks,
DAve

"RonKZ650" wrote in message
...
As I mentioned, the CRT filaments are not lit at all.
I'll check the CRT board to see if anything shows up there.
Thanks,

If the filiments are not lit, you have no HV.

Not necessarily. Could just be an open on the filament line from the FBT.
Could be an open filament.

Leonard

On Wed, 15 Dec 2004 00:11:54 -0500, "Leonard Caillouet"
wrote:


"RonKZ650" wrote in message
...
As I mentioned, the CRT filaments are not lit at all.
I'll check the CRT board to see if anything shows up there.
Thanks,

If the filiments are not lit, you have no HV.

Not necessarily. Could just be an open on the filament line from the FBT.
Could be an open filament.

Leonard

Thanks for the info - as I mentioned I *suspect* there
is HT, because I get the sense and sounds of static on the
screen when I first turn it on. I get normal audio,
but no raster at all.

Appreciate all the comments!
Dave

"davexnet02" wrote in message
...
On Tue, 14 Dec 2004 15:58:17 -0500, "Art"
wrote:

Loss of +200 VDC to the video driver/output. Defective Video
driver/output.
Defective CRT, Etc Post the diagnostic measurements you have actually
made
so we may asset what you have done already then render assistance.
Hi Art, thanks for responding.
Alas, I have not made any "diagnostic measurements", just some
observations. I am not a qualified TV servicer, but I do have some
electronics background, and I have a copy of the service manual.

I have not done anything except resolder all the pins on the
power supply board transformers. (Sony G board).
Problem remains.

Perhaps the TV has reached the end of it's useful life,
or at least it's cost effective life.

Dave



Don't condemn it just yet, it's quite likely it can be brought back to life
for a bit more, and perhaps much more useful service.

"davexnet02" wrote in message
...
On Wed, 15 Dec 2004 00:11:54 -0500, "Leonard Caillouet"
wrote:


"RonKZ650" wrote in message
...
As I mentioned, the CRT filaments are not lit at all.
I'll check the CRT board to see if anything shows up there.
Thanks,

If the filiments are not lit, you have no HV.

Not necessarily. Could just be an open on the filament line from the
FBT.
Could be an open filament.

Leonard

Thanks for the info - as I mentioned I *suspect* there
is HT, because I get the sense and sounds of static on the
screen when I first turn it on. I get normal audio,
but no raster at all.

Appreciate all the comments!
Dave

Look for cracked solder joints on the neck board or bulging or leaking
electrolytic capacitors. It's quite possible the picture was washed out due
to low filament voltage.

On Wed, 15 Dec 2004 05:51:02 GMT, "James Sweet"
wrote:


"davexnet02" wrote in message
.. .
On Wed, 15 Dec 2004 00:11:54 -0500, "Leonard Caillouet"
wrote:


"RonKZ650" wrote in message
...
As I mentioned, the CRT filaments are not lit at all.
I'll check the CRT board to see if anything shows up there.
Thanks,

If the filiments are not lit, you have no HV.

Not necessarily. Could just be an open on the filament line from the
FBT.
Could be an open filament.

Leonard

Thanks for the info - as I mentioned I *suspect* there
is HT, because I get the sense and sounds of static on the
screen when I first turn it on. I get normal audio,
but no raster at all.

Appreciate all the comments!
Dave

Look for cracked solder joints on the neck board or bulging or leaking
electrolytic capacitors. It's quite possible the picture was washed out due
to low filament voltage.

Thanks James, I'll check it carefully.
The washed out picture went hand in hand with something
else I thought suspicious. It happened at the same time
it developed the blue cast, and the blue cast itself occurred
after particularly bright and contrasty scenes were sustained for
a while.

At the beginning, if I kept the contrast low, after a couple of
hours, the blue cast dissipated. But towards the end, the blue cast
was more or less constant. This whole episode has been about 3 months.

I think it was leonard who said that it sounded as if the tube
was failing.
Dave

On Wed, 15 Dec 2004 05:51:02 GMT, "James Sweet"
wrote:


"davexnet02" wrote in message
.. .
On Wed, 15 Dec 2004 00:11:54 -0500, "Leonard Caillouet"
wrote:


"RonKZ650" wrote in message
...
As I mentioned, the CRT filaments are not lit at all.
I'll check the CRT board to see if anything shows up there.

Look for cracked solder joints on the neck board or bulging or leaking
electrolytic capacitors. It's quite possible the picture was washed out due
to low filament voltage.

I made some progress on this. I turned up the G2 voltage a
little, and I was able to see that the filaments were lit,
but still no picture.

I pulled the main chassis from the TV and inspected the
underside. I paid attention to the area's close to the
FBT, as this seemed to be where the horizontal and vertical
deflection business was done.

I resoldered some connections, to capacitors, resisitors,
and transformers, anything I could see that looked bad.

I put it back in and turned on the TV.
For 20 minutes, nothing but sound & black screen, (as before)
then all of a sudden - a very weird, electrical crackle, a flash
of bright blue on the screen, followed by normal operation 2 seconds
later. It's been working fine for two days now.
Even the line pairing I was getting in the top half of the screen
is greatly dimished.

A couple of observations though, when I turn of the TV now,
there's a brief display of color spots on the screen in the
center - just for a few seconds. First time I've seen that
on this set.
Second, the G2 voltage. I marked it with a pen before I disturbed
it, and retuned it as close as is possible with this method, but I
don't think it's exact. Is it a big deal if it's slightly out?
regards,
Dave

I would still think you should have the set properly checked by a tech who
is experienced with the model series of Sony set that you have.

Things like the power supply, scans, and power supply should be properly
checked. There is a procedure for setting up the G2 voltage. The details
should be in the service manual for your set. If it a little low, it is not
going to be bad for the CRT, but if it is high, it will accelerate its
deteriation, due to excessive beam current.

You may still have an intermittant solder connection in the set, or
something that is mechanicaly not right, going by how you described that it
came back to life, and is reacting now. This should be properly checked.

Take care about the safety issues when working on TV sets. This is most
important for yourself.

--

Jerry G.
=====

"davexnet02" wrote in message
...
On Wed, 15 Dec 2004 05:51:02 GMT, "James Sweet"
wrote:


"davexnet02" wrote in message
.. .
On Wed, 15 Dec 2004 00:11:54 -0500, "Leonard Caillouet"
wrote:


"RonKZ650" wrote in message
...
As I mentioned, the CRT filaments are not lit at all.
I'll check the CRT board to see if anything shows up there.

Look for cracked solder joints on the neck board or bulging or leaking
electrolytic capacitors. It's quite possible the picture was washed out due
to low filament voltage.

I made some progress on this. I turned up the G2 voltage a
little, and I was able to see that the filaments were lit,
but still no picture.

I pulled the main chassis from the TV and inspected the
underside. I paid attention to the area's close to the
FBT, as this seemed to be where the horizontal and vertical
deflection business was done.

I resoldered some connections, to capacitors, resisitors,
and transformers, anything I could see that looked bad.

I put it back in and turned on the TV.
For 20 minutes, nothing but sound & black screen, (as before)
then all of a sudden - a very weird, electrical crackle, a flash
of bright blue on the screen, followed by normal operation 2 seconds
later. It's been working fine for two days now.
Even the line pairing I was getting in the top half of the screen
is greatly dimished.

A couple of observations though, when I turn of the TV now,
there's a brief display of color spots on the screen in the
center - just for a few seconds. First time I've seen that
on this set.
Second, the G2 voltage. I marked it with a pen before I disturbed
it, and retuned it as close as is possible with this method, but I
don't think it's exact. Is it a big deal if it's slightly out?
regards,
Dave

On Tue, 28 Dec 2004 22:26:40 -0500, "Jerry G."
wrote:

I would still think you should have the set properly checked by a tech who
is experienced with the model series of Sony set that you have.

Things like the power supply, scans, and power supply should be properly
checked. There is a procedure for setting up the G2 voltage. The details
should be in the service manual for your set. If it a little low, it is not
going to be bad for the CRT, but if it is high, it will accelerate its
deteriation, due to excessive beam current.

You may still have an intermittant solder connection in the set, or
something that is mechanicaly not right, going by how you described that it
came back to life, and is reacting now. This should be properly checked.

Take care about the safety issues when working on TV sets. This is most
important for yourself.
Hi Jerry,
thanks for the feedback. I do have the service manual,
but I don't have, nor am I versed in the operation of,
an oscilloscope. Must admit, it would be good to have
it and know how to use it.
There's another setting, sub-contrast (SPIX), that also
requires a scope to set it.

I *did* have a tech repair the powersupply 4 months ago,
but he did not check the alignment. I believe this is the
source of many of the problems I've experienced since.
Such as excesively high brighness and contrast.



Dave

On Tue, 14 Dec 2004 18:47:23 GMT, davexnet02
wrote:

Hello,
I'm trying to diagnose a fault that just developed,
I get sound, and I can feel/here the static electricy
that's generated on the screen when it's turned on.
The screen remains black.

I took the back off the TV and I can see that all
of the neck filamants are unlit.

Please advise. This is a 1992 Sony 27 inch XBR
(kv27-xbr35) Thanks for any assistance.

Dave

Have you checked the IK voltage on the CRT board? If .6 or so, the CRT
likely has a weak cathode. If 2.2 or so, there is likely another
problem.

Tom

On Wed, 15 Dec 2004 04:27:24 GMT, davexnet02
wrote:

On Wed, 15 Dec 2004 04:16:15 GMT, Alan Harriman
wrote:

On Tue, 14 Dec 2004 18:47:23 GMT, davexnet02
wrote:

Hello,
I'm trying to diagnose a fault that just developed,
I get sound, and I can feel/here the static electricy
that's generated on the screen when it's turned on.
The screen remains black.

If the red LED flashes, the set may be in IK blanking. Try turning the
screen control up slightly. If the picture comes in, it *could*
indicate a weak CRT. However, we had a Sony KV27EX25 in the shop today
that had no raster. Turning up the screen restored the pix, which is
often associated with a weak picture tube. But the CRT on this set
checked good. Further checking showed a low screen (G2) voltage. We
found an open 1 meg resistor on the CRT board in series with the
screen control. Replacing the resistor restored an excellent picture.

Alan Harriman
Hi Alan, never seen a flashing LED on this set.
Was that implemented in the 1992 models?

I had suspicions about a weak CRT prior to this failure.
The grey scale was off (too blue) and it was satrting to wash out.

As I mentioned, the CRT filaments are not lit at all.

Ooops...read your first post too hastily...maybe they have voltage but
you can't see them as being lit. Have you looked at them in the dark?
It is possible to "roll your own" filament transformer, but you should
have a qualified TV repair person do it, as the filament voltage's
value may be critical to the life of the CRT.

Tom
I'll check the CRT board to see if anything shows up there.
Thanks,
DAve

On Wed, 29 Dec 2004 02:30:27 GMT, davexnet02
wrote:

On Wed, 15 Dec 2004 05:51:02 GMT, "James Sweet"
wrote:


"davexnet02" wrote in message
. ..
On Wed, 15 Dec 2004 00:11:54 -0500, "Leonard Caillouet"
wrote:


"RonKZ650" wrote in message
...
As I mentioned, the CRT filaments are not lit at all.
I'll check the CRT board to see if anything shows up there.

Look for cracked solder joints on the neck board or bulging or leaking
electrolytic capacitors. It's quite possible the picture was washed out due
to low filament voltage.

I made some progress on this. I turned up the G2 voltage a
little, and I was able to see that the filaments were lit,
but still no picture.

I pulled the main chassis from the TV and inspected the
underside. I paid attention to the area's close to the
FBT, as this seemed to be where the horizontal and vertical
deflection business was done.

I resoldered some connections, to capacitors, resisitors,
and transformers, anything I could see that looked bad.

I put it back in and turned on the TV.
For 20 minutes, nothing but sound & black screen, (as before)
then all of a sudden - a very weird, electrical crackle, a flash
of bright blue on the screen, followed by normal operation 2 seconds
later. It's been working fine for two days now.
Even the line pairing I was getting in the top half of the screen
is greatly dimished.


The heat finally caused a G1 short in the CRT to remove itself for
now, I think.

Tom
A couple of observations though, when I turn of the TV now,
there's a brief display of color spots on the screen in the
center - just for a few seconds. First time I've seen that
on this set.
Second, the G2 voltage. I marked it with a pen before I disturbed
it, and retuned it as close as is possible with this method, but I
don't think it's exact. Is it a big deal if it's slightly out?
regards,
Dave

On Wed, 29 Dec 2004 21:47:22 GMT, Tom MacIntyre
wrote:

On Tue, 14 Dec 2004 18:47:23 GMT, davexnet02
wrote:

Hello,
I'm trying to diagnose a fault that just developed,
I get sound, and I can feel/here the static electricy
that's generated on the screen when it's turned on.
The screen remains black.

I took the back off the TV and I can see that all
of the neck filamants are unlit.

Please advise. This is a 1992 Sony 27 inch XBR
(kv27-xbr35) Thanks for any assistance.

Dave

Have you checked the IK voltage on the CRT board? If .6 or so, the CRT
likely has a weak cathode. If 2.2 or so, there is likely another
problem.

Tom
HI Tom,
how is this measured? Presumably the black is grounded somewhere
while the red is put on the test point.
Should the TV be set to normal viewing conditions (STANDARD
setting)
Thanks,
Dave