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jakdedert jakdedert is offline
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Default Sharp LL- T17A4-B lcd Monitor

jakdedert wrote:
Bought from the 'E' place for cheap. Reported symptom: video comes on
and fades out. Figured it was high ESR smps caps.

Actual symptom: backlight comes on, image consist of random horizontal
lines, which eventually--after some intermittent vertical
scrolling--settle into a very nice image. Takes like two minutes to
warm up. Shutting the monitor down for some unknown time starts the
process all over again. Continuous viewing yields a stable image with
good resolution, brightness and linearity. Shutting down for short
periods is not problematic.

There is only one HV (100 @ 400v) cap in the ps. ESR is .46, which I
assume is within tolerance. Other caps in the ps also seem fine.

This presents so like a classic cap issue (needs to warm up), that I'm
going to next pull the video board and check caps there...possibly get
some freeze spray and see if I can duplicate symptoms that way.

Reality check: any problem with the above procedure, or experience with
this particular monitor? Any suggestions as to where to go if the above
doesn't produce a dx and fix?

Thanks as always,

jak


So far, no luck. ESRd all caps on video board. All good. Bad news is
that monitor rarely straightens up anymore. I got it to display
correctly only once this evening, so no chance of trying to reproduce
symptom via freezing components. Power supply voltages appear nominal
and clean. No effect from flexing components. Reseated all cables on
the video board.....

It looks like the horizonal rows are not being addressed, as the current
display is a series of fine vertical lines of whatever color is
predominant in that area of the display. Still some strange horizontal
scrolling effects when first powered, but they only last a few
seconds...two or three horizontal bars scroll down the screen, then
disappear.


Any help here? Is this toast [beyond my ability to fix...]? My scope
(20 mHz) is not fast enough to look at the video timing....

jak