Hello all,

Recently, the Sony GDM-FW900 (a 24" 16:9 CRT) I purchased back in 2000
gave up the ghost. Given the use I've put it to these past few years,
and a couple of abusive moves along the way, I can hardly claim that I
didn't get my money's worth out of it, but that doesn't stop me from
wanting to see if I can't wring just a little bit more.

While basically competent (though perhaps not by the standards of this
group), I really don't know anything about monitor repair. I've read
the sci.electronics.repair FAQ on the subject, which was very helpful
but I've still got that "if you touch the inside of your monitor, you
die" thing in the back of my head.

This is a really, really complicated monitor, so I was hoping that with
some description, someone might point me in the right direction and
narrow down the possibilities.

The history:

This is not the original monitor. It was replaced after about a year
because my old one would occasionally make a popping sound. The new
one, however, has always done the same thing, if less frequently
(perhaps once a month). The popping sound (which sounds exactly like a
knuckle cracking) is typically preceded by a period of increasing
fuzziness which may last for just a second or as long as a couple of
minutes. As soon as it pops, the crystal is razor sharp again (perhaps
even sharper than it usually is, or perhaps that's just a brain trick).

The current problem originally manifested as an inability to wake up
from "sleep" mode. Powering off and on wouldn't do anything, but
unplugging everything and leaving it overnight would often cause it to
make the "turning off" noises at some point hours later, after which it
would work.

I was able to get around this problem for a month or so by simply
leaving it on 24x7. Perhaps as a consequence, when the light of my life
accidentally put it in sleep mode, it never came back.

The symptoms:

When you turn it on, there's a single really click, which is exactly as
it has ever been. However, it no longer attempts to degauss.

With no input connected, the monitor comes on and goes to sleep. It
looks like it's working. If you try anything to get a picture, it goes
into the monitor's error mode, which is the power LED flashing orange.
Not even the service manual (which I have) says what the flashes mean,
it just has a copy of the owner's manual page; both say to "count the
seconds between orange flashes of the power indicator and inform your
authorized Sony dealer."

What I've tried:

My gut reaction is that something in there is slowly picking up a charge
in a very naughty way. When it picks up enough charge, the resulting
field is enough to defocus the electron beam. Since the precessing blur
appears mostly uniform over the screen, my guess is it would need to be
toward the back, near the neck of the CRT.

I don't know if the "popping" problem is at all related to the
won't-display problem, but it's certainly a coincidence that the other
problem also seems somehow related to a weird charge, given the way it
would initially "discharge" and start working if left alone for a few hours.

Research suggests that this may be arcing from the flyback, but I bet
that's a part that's too expensive / hard to replace to just "try it and
see." Does anyone have any feel for how much these cost or how hard
they are to replace? (I have rudimentary soldering skills / equipment.)

A more baseless guess is that this "extra charge" I've imagined up is
somehow fooling part of the monitor into thinking it's already on,
keeping it from waking up from sleep or powering on fresh.

I've disassembled it and checked for fuses or "obvious" fusable
resistors with no luck.

I think the "missing degauss" when it starts up is suggestive of
something as well, I'm just not sure what.

To reiterate, I've gotten my money out of this monitor. I've already
ordered a replacement (though it's several weeks away). But if I can
fix this to at least "sort of work" (particularly for the next several
weeks ;-) ), I'd like to keep some lead out of the landfill for awhile
longer. If I can find a fairly definitive fix that will put another
year or two of life into it, I may be able to find a worthwhile
organization to donate it to after the replacement arrives because it
really is a great monitor and I'm sure somebody could use it.

While researching this problem I did quite a few Google searches, and
there are a lot of people on this group who know an amazing amount about
this stuff. All I'm hoping is that somebody can kick me in the right
direction on this, so I can squeeze whatever might be left out of this
guy. I should be able to provide any necessary information.

Thank you so much for any help/advice!

Jeff

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Jeff Wheelhouse