samsung TV picture fading

Paul

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Jul 27, 1998, 3:00:00 AM7/27/98

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I have a Samsung Television model CB6630Z that after a short time the
picture fades to black.
It seems to happen if say the channel up button on the remote is held down,
then the picture starts to fade away after a minute or so and retrace lines
begin to show.Then the screen goes black,the sound continues to operate all
the time.
If powered down the fault seems to reset.
If any suggestions as to the cause or a common component to check can be
supplied they would be most appreciated...Thankyou

Tom MacIntyre

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Jul 27, 1998, 3:00:00 AM7/27/98

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"Paul" <paul...@sympac.com.au> wrote:

My guess is that the remote has nothing to do with it...could be
wrong, though. It's likely a short in the CRT, although I've seen bad
heater connections on the CRT socket on a few Samsungs...the retrace
lines seem to indicate the tube itself. Make sure you observe all
safety precautions if you decide to look at it yourself. Good luck.

Tom

>
>

Sam Goldwasser

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Jul 27, 1998, 3:00:00 AM7/27/98

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If the fading is a gradual process I doubt the CRT. A bad filament
connection wouldn't result in retrace lines, just fade to black. Possibly
a bad connection in a power supply or video circuit? Troubleshooting would
require mesuaring voltages and/or waveforms starting at the CRT socket and
working backwards. See the FAQs for info and SAFETY.

--- sam : Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Latest Sam stuff: http://www.repairfaq.org/sam/
Lasers: http://www.repairfaq.org/sam/lasersam.htm
http://www.misty.com/~don/lasersam.html

Janssen Erik

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Jul 28, 1998, 3:00:00 AM7/28/98

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Paul wrote:
>
> I have a Samsung Television model CB6630Z that after a short time the
> picture fades to black.
> It seems to happen if say the channel up button on the remote is held down,
> then the picture starts to fade away after a minute or so and retrace lines
> begin to show.Then the screen goes black,the sound continues to operate all
> the time.
> If powered down the fault seems to reset.
> If any suggestions as to the cause or a common component to check can be
> supplied they would be most appreciated...Thankyou

hi,
I recently had a similar problem on a Samsung-set. It got me confused
too. After a lot a of spraying,hitting and bending I almost gave up on
this one. Finally it seemed to be a false contact in the EHT.
It was an EHT with integrated Vg2 pot-meter. By tilting this potmeter
I could reproduce the problem. My set became stable after using some
contact-spray.
I hope this might help you.
Kind regards

Larry Sabo

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Jul 28, 1998, 3:00:00 AM7/28/98

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You sprayed contact cleaner into the screen pot? Ayone any concerns
about arc-over/fire because of this?

Larry

Video Services

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Jul 28, 1998, 3:00:00 AM7/28/98

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Spraying,hitting and bending ?????
Troubleshooting, I guess I missed in "fix-it" school.

Give me a break.

Rex
Video Services

Janssen Erik

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Jul 28, 1998, 3:00:00 AM7/28/98

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Larry Sabo wrote:
>
> You sprayed contact cleaner into the screen pot? Ayone any concerns
> about arc-over/fire because of this?
>
> Larry
>

Hi,

I didn't had any problem with arc-over...and I had it playing for
several hours.
If I turned the pot , I could feel that there was a small click
so the pot probably had a small pit burned in the surface.
I agree that depending on the state of the pot... that my solution
isn't a final fix... but at least you should be able to locate the
problem. In this case I could define that the problem was in the pot
and one had to replace the complete EHT.
Anyway, on older TV-sets I've seen often common carbon-pots to adjust
the Vg2.
Erik.