Hi there - I'm hoping someone here has some idea of what is going on
here.

I've acquired a JVC GD-V4200PZW 42" plasma display cheaply, as it is
ill, and the owner decided to throw it out without attempting to repair
it... I've investigated the symptoms, and they are as follows:

Upon initial powerup, with no connections, OSD works fine, all menus on
OSD work fine, OSD looks fine... From this, I figure the actual display
itself is fine.

Upon connecting a composite video (or s-video) input, the resulting
display is initially completely illegible, and has magenta streaks all
over the place, dancing in a noiselike fashion. After a power cycle,
the result is sometimes magenta streaks, sometimes cyan, sometimes
yellow (which always seems to saturate to an entirely yellow display,
rapidly). Most of the time, RG&B pixels are all on. Over time, the
image gains some stability, however is completely useless as a display,
as there is still a large amount of noise.

If VGA is connected, the initial display will always be either green
tinted, or normal colour. Power cycling brings about one or the other
each time, however cycling through inputs tends to have less of an
effect. The display is initially extremely unstable, however over time
gains stability, and is covered in lines which almost look like the
Moire effect, however these lines gradually become narrower, and tend
towards the horizontal (initially, they are all over the shop, and
kink). After ~1 hour of uptime, the image is fairly stable, however is
still dominated by grey lines. After several more hours of uptime,
black incursions begin to appear, flickering briefly, and taking the
form of a line reaching across the screen, with a black 'ramp' up
towards the line from below, on the left side of the screen. All pixels
horizontally aligned with the 'ramp' are shifted accordingly with the
ramp to the right.

I've dismantled the unit, and have checked for dry joints, and for
damaged capacitors (there are some *huge* electrolytics in there),
however can't see anything obviously wrong - the time dependancy of the
problems makes me suspect the capacitors, but I'm not sure...

If anyone has any experience in this area at all, any info would be
much appreciated!

Cheers!

Max

It seems the black spikes happen only when there are areas of the
screen which contrast - if it's one uniform colour, or range of
colours, no problem. Contrasty scenes cause issues. I'm actually using
the display to post now, but it's painful on the eyes!

Your unit has to be properly serviced. Most of the time, the actual Plasma
tube is not defective. The support modules that drive it can fail. These
sets are generally serviced at the modular level, just like when servicing a
computer.

The service tech would most likely first try the power supply, or the main
drive module to the screen, and work from there. In some of the older units,
the main Plasma drive module was built directly on to the back of the Plasma
display unit. If this is defective, then the cost to service it will be too
high.

There are some modules that may require specific types of set-ups. You will
most likely not be able to do these set-ups at home, with the resources
available to you. Some of the procedures require specific calibration and
interface equipment, and the factory service manual. There are also some
diagnostics done to troubleshoot and adjust these type of sets. The complete
technology and approach is very different than what it used to be with the
older TV sets.

I am sure that if you found the set in the trash, it most likely had an
estimate done already, and the owner found it to be too expensive to
service, in relation to replacing it for a complete new Plasma set. These
sets are not something someone would throw away without investigating in to
what may be wrong with it.

--

Jerry G.
======


"MAdaXe" wrote in message
ups.com...
Hi there - I'm hoping someone here has some idea of what is going on
here.

I've acquired a JVC GD-V4200PZW 42" plasma display cheaply, as it is
ill, and the owner decided to throw it out without attempting to repair
it... I've investigated the symptoms, and they are as follows:

Upon initial powerup, with no connections, OSD works fine, all menus on
OSD work fine, OSD looks fine... From this, I figure the actual display
itself is fine.

Upon connecting a composite video (or s-video) input, the resulting
display is initially completely illegible, and has magenta streaks all
over the place, dancing in a noiselike fashion. After a power cycle,
the result is sometimes magenta streaks, sometimes cyan, sometimes
yellow (which always seems to saturate to an entirely yellow display,
rapidly). Most of the time, RG&B pixels are all on. Over time, the
image gains some stability, however is completely useless as a display,
as there is still a large amount of noise.

If VGA is connected, the initial display will always be either green
tinted, or normal colour. Power cycling brings about one or the other
each time, however cycling through inputs tends to have less of an
effect. The display is initially extremely unstable, however over time
gains stability, and is covered in lines which almost look like the
Moire effect, however these lines gradually become narrower, and tend
towards the horizontal (initially, they are all over the shop, and
kink). After ~1 hour of uptime, the image is fairly stable, however is
still dominated by grey lines. After several more hours of uptime,
black incursions begin to appear, flickering briefly, and taking the
form of a line reaching across the screen, with a black 'ramp' up
towards the line from below, on the left side of the screen. All pixels
horizontally aligned with the 'ramp' are shifted accordingly with the
ramp to the right.

I've dismantled the unit, and have checked for dry joints, and for
damaged capacitors (there are some *huge* electrolytics in there),
however can't see anything obviously wrong - the time dependancy of the
problems makes me suspect the capacitors, but I'm not sure...

If anyone has any experience in this area at all, any info would be
much appreciated!

Cheers!

Max