Tinkering with a sick LCD...
 

I've been given an LG Flatron 566 15" LCD that is sick... originally it
would turn on and display a good picture, but over time the image would
start to wash out and turn blurry. Now when I turn it on it just goes
mostly white with some horizontal and vertical lines.

The problem seems to be with the later stage of the display circuitry
because it will turn on, and behaves as expected when there is no signal
(goes black after a few seconds and comes back on when the signal returns).
I also managed to somehow enter a diagnostic mode from the front panel that
caused it to cycle through various colours on the screen.

There was one bad capacitor (bulged and leaking) in the power supply, which
I replaced, so I'm wondering if I should just go and replace all the other
electrolytic caps.. I took the main board out and put it in a ziploc bag in
the freezer, and after about 20 minutes I reconnected it, and got something
much more closely resembling a display of the signal from the PC. I was
looking at a page of text and I could see stretched vertical patches where
the letters were being displayed... the horizontal was more well defined
than the vertical.
Also, although I could see the screen change as I did things on the PC, the
response time was extremely high.
So I'm wondering if the temperature sensitivity maybe points toward bad
caps.

I realize there's not a whole lot to service on these things, this one is
just one main chip and some caps, so the likelyhood of repairing is slim,
but I have nothing to lose, and enjoy trying to fix it, even if it is a
wasted effort...

Tinkering with a sick LCD...
 

JM wrote:
I've been given an LG Flatron 566 15" LCD that is sick... originally it
would turn on and display a good picture, but over time the image would
start to wash out and turn blurry. Now when I turn it on it just goes
mostly white with some horizontal and vertical lines.

The problem seems to be with the later stage of the display circuitry
because it will turn on, and behaves as expected when there is no signal
(goes black after a few seconds and comes back on when the signal returns).
I also managed to somehow enter a diagnostic mode from the front panel that
caused it to cycle through various colours on the screen.

There was one bad capacitor (bulged and leaking) in the power supply, which
I replaced, so I'm wondering if I should just go and replace all the other
electrolytic caps.. I took the main board out and put it in a ziploc bag in
the freezer, and after about 20 minutes I reconnected it, and got something
much more closely resembling a display of the signal from the PC. I was
looking at a page of text and I could see stretched vertical patches where
the letters were being displayed... the horizontal was more well defined
than the vertical.
Also, although I could see the screen change as I did things on the PC, the
response time was extremely high.
So I'm wondering if the temperature sensitivity maybe points toward bad
caps.

I realize there's not a whole lot to service on these things, this one is
just one main chip and some caps, so the likelyhood of repairing is slim,
but I have nothing to lose, and enjoy trying to fix it, even if it is a
wasted effort...



replace the caps with at least the same value, but if possible
replace 25V caps with 50V caps etc.
rw