Dead pixels on CRT
 

http://tinyurl.com/yz3eko4

How does a CRT end up with a vertical line of dead pixels?

Sylvia.

Dead pixels on CRT
 

Sylvia Else wrote:
http://tinyurl.com/yz3eko4

How does a CRT end up with a vertical line of dead pixels?


Faulty digital frame buffer.

--
Adrian C

Dead pixels on CRT
 

Sylvia Else Inscribed thus:

http://tinyurl.com/yz3eko4

How does a CRT end up with a vertical line of dead pixels?

Sylvia.

I've never seen a crt with a line of dead anything ! If its a dead
straight vertical line then its unlikely to be the crt. Possibly some
artifact of the video feed... maybe ?

--
Best Regards:
Baron.

Dead pixels on CRT
 

On Wed, 04 Nov 2009 22:22:06 +1100, Sylvia Else
wrote:

http://tinyurl.com/yz3eko4

How does a CRT end up with a vertical line of dead pixels?

Sylvia.

It processes the signal as digital then converts to analog for the CRT
driver. I'd guess it is not going to be worth trying to fix, something
is gone in the digital section(s).

Dead pixels on CRT
 

PeterD wrote in
:

On Wed, 04 Nov 2009 22:22:06 +1100, Sylvia Else
wrote:

http://tinyurl.com/yz3eko4

How does a CRT end up with a vertical line of dead pixels?

Sylvia.

It processes the signal as digital then converts to analog for the CRT
driver. I'd guess it is not going to be worth trying to fix, something
is gone in the digital section(s).


some chip in the frame memory?

--
Jim Yanik
jyanik
at
localnet
dot com

Dead pixels on CRT
 

Jim Yanik wrote:
PeterD wrote in
:

On Wed, 04 Nov 2009 22:22:06 +1100, Sylvia Else
wrote:

http://tinyurl.com/yz3eko4

How does a CRT end up with a vertical line of dead pixels?

Sylvia.
It processes the signal as digital then converts to analog for the CRT
driver. I'd guess it is not going to be worth trying to fix, something
is gone in the digital section(s).


some chip in the frame memory?

Could it possibly be a stabilising wire as in the Trinitrons(I know they
are usually horizontal)

Ron

Dead pixels on CRT
 

Sylvia Else wrote:
http://tinyurl.com/yz3eko4

How does a CRT end up with a vertical line of dead pixels?

It doesn't. : I suspect there are *two* "lines of dead
pixels" in this CRT -- though only one is probably visible
(luck?).

There are two (3?) wires that cross the screen (usually horizontally
but since this is a wider aspect ratio screen, they might be
oriented vertically) used to stabilize the aperture grill.

Dead pixels on CRT
 

In article ,
baron wrote:

http://tinyurl.com/yz3eko4

How does a CRT end up with a vertical line of dead pixels?

I've never seen a crt with a line of dead anything ! If its a dead
straight vertical line then its unlikely to be the crt. Possibly some
artifact of the video feed... maybe ?

It's a Trinitron tube. This type of CRT doesn't use a shadow mask.
Instead, it uses a shadow grid - a bunch of very fine parallel
vertical wires, stretched from top to bottom.

An occasional fault in a Trinotron is for one of the shadow wires to
end up out of position. If I recall properly, this can happen if
somebody uses an external degausser - the magnetic field can shove one
wire across the one next to it. This will cause a subtle vertical
stripe to appear on the screen.,. looks rather like a row of dead
pixels.

I think there's a Field Engineering Repair procedure for this...
rapping sideways on the case, with just the right amount of force, to
jar the stuck wires apart and allow the displaced one to snap back to
its correct position. I don't know how much force is required.

One can sometimes see this effect even on a perfectly good
Trinotron tube... I think that in some models there are vertical
reinforcing rods in the grid assembly which can produce a shadow on
the tube.

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

Dead pixels on CRT
 

Dave Platt wrote:

In article ,
baron wrote:

http://tinyurl.com/yz3eko4

How does a CRT end up with a vertical line of dead pixels?

I've never seen a crt with a line of dead anything ! If its a dead
straight vertical line then its unlikely to be the crt. Possibly some
artifact of the video feed... maybe ?

It's a Trinitron tube. This type of CRT doesn't use a shadow mask.
Instead, it uses a shadow grid - a bunch of very fine parallel
vertical wires, stretched from top to bottom.

An occasional fault in a Trinotron is for one of the shadow wires to
end up out of position. If I recall properly, this can happen if
somebody uses an external degausser - the magnetic field can shove one
wire across the one next to it. This will cause a subtle vertical
stripe to appear on the screen.,. looks rather like a row of dead
pixels.

I think there's a Field Engineering Repair procedure for this...
rapping sideways on the case, with just the right amount of force, to
jar the stuck wires apart and allow the displaced one to snap back to
its correct position. I don't know how much force is required.

One can sometimes see this effect even on a perfectly good
Trinotron tube... I think that in some models there are vertical
reinforcing rods in the grid assembly which can produce a shadow on
the tube.


Dave: Thanks for those notes. I wasn't aware of the vertical wire grid
in a Trinitron tube. I knew about the two horizontal ones. I can
actually see those in my screen.

--
Best Regards:
Baron.

Dead pixels on CRT
 

Adrian C wrote:
Sylvia Else wrote:
http://tinyurl.com/yz3eko4

How does a CRT end up with a vertical line of dead pixels?


Faulty digital frame buffer.

I'd be surprised if a television like that had a frame buffer. What
would it be for?

Sylvia.

Dead pixels on CRT
 

Sylvia Else wrote:
Adrian C wrote:
How does a CRT end up with a vertical line of dead pixels?

Faulty digital frame buffer.

I'd be surprised if a television like that had a frame buffer. What
would it be for?

The set features a digital tuner.

--
Adrian C

Dead pixels on CRT
 

Adrian C wrote:
Sylvia Else wrote:
Adrian C wrote:
How does a CRT end up with a vertical line of dead pixels?

Faulty digital frame buffer.

I'd be surprised if a television like that had a frame buffer. What
would it be for?

The set features a digital tuner.

Fair point. Still, if the pixels were dead only in digital reception
mode, I think the seller would have said so.

Sylvia.

Dead pixels on CRT
 

On Thu, 05 Nov 2009 18:13:57 +1100, Sylvia Else
wrote:

Adrian C wrote:
Sylvia Else wrote:
http://tinyurl.com/yz3eko4

How does a CRT end up with a vertical line of dead pixels?


Faulty digital frame buffer.

I'd be surprised if a television like that had a frame buffer. What
would it be for?

Sylvia.

Read the specifications, the video is digital to the CRT. Basically a
'cross-over' model on the way to full (LCD etc.) digital. Frame
buffers are not unusual in these types of sets (the wide-screen
variety)

Dead pixels on CRT
 

Sylvia Else wrote:
Adrian C wrote:
Sylvia Else wrote:
http://tinyurl.com/yz3eko4

How does a CRT end up with a vertical line of dead pixels?

Faulty digital frame buffer.

I'd be surprised if a television like that had a frame buffer. What
would it be for?

Sylvia.
Freeze pic/digital zoom in/out.

Dead pixels on CRT
 

It's entirely possible that the fault is actually as you've suggested.
I'd try degaussing the middle of the line, in the hopes of shaking
the wire loose.

Get a rubber mallet and hit it in the face - pretty hard. If the
aperture grill lines are twisted, that will set them straight. I've
done this after a nasty trip with an external degaussing coil.

Simply lifting the set and dropping it gently (???) might fix the problem.
This happend to my Sony WEGA in March when it was moved from the LR to the
BR. The splotch disappeared, and has not come back.