This full HD Plasma set has an oddball fault.
It will have a perfect picture, then a single line would appear at random places on the upper half of the picture.
The line would be fully white or a shade of grey, and the full length of the screen.
Then the top half of the picture--would completely disappear. The line however would bounce around randomly, sometimes disappearing leaving a black upper half....
I had recently scrapped the same model set that had a couple of issues, the main one and reason for scrapping--was a few dead pixel lines running fully vertically--COF chip/panel issue.
--It also had a condition where every other horizontal line of pixels wasn't driven/working, giving the effect of an old CRT set where clearly observable scan-lines are present, and an occasional vertical double image with vertical bounce.
So--Back to the faulty set. First I replace the Y-Buffers.
Still the same. Checked all the multi-way ribbons, all good.
Then goes the Control-Board. No different, Still half a picture, line bobbing about in the black half.
Then I change the Mainboard--because I had one there. No change.
OK--Changed the Y-SUS.....
Ah--Now we have a change, Full screen, but every other line missing, and double-image with bounce (just as it was from the scrapped donor set)
It appears, the address info on both these Y-SUS has issues, all be it of a different nature.
There appears to be three sets of chips which are responsible for the address/clock info on the Y that eventually end up at the Y-Buffer boards.....
Ive not determined--Yet--which chip is causing the issues....
It will have a perfect picture, then a single line would appear at random places on the upper half of the picture.
The line would be fully white or a shade of grey, and the full length of the screen.
Then the top half of the picture--would completely disappear. The line however would bounce around randomly, sometimes disappearing leaving a black upper half....
I had recently scrapped the same model set that had a couple of issues, the main one and reason for scrapping--was a few dead pixel lines running fully vertically--COF chip/panel issue.
--It also had a condition where every other horizontal line of pixels wasn't driven/working, giving the effect of an old CRT set where clearly observable scan-lines are present, and an occasional vertical double image with vertical bounce.
So--Back to the faulty set. First I replace the Y-Buffers.
Still the same. Checked all the multi-way ribbons, all good.
Then goes the Control-Board. No different, Still half a picture, line bobbing about in the black half.
Then I change the Mainboard--because I had one there. No change.
OK--Changed the Y-SUS.....
Ah--Now we have a change, Full screen, but every other line missing, and double-image with bounce (just as it was from the scrapped donor set)
It appears, the address info on both these Y-SUS has issues, all be it of a different nature.
There appears to be three sets of chips which are responsible for the address/clock info on the Y that eventually end up at the Y-Buffer boards.....
Ive not determined--Yet--which chip is causing the issues....
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