HP LP3065 monitor half bad screen

[mjsbv]

I've just aquired an HP LP3065 monitor, with a partial functioning screen. I've read through previous posts about this monitor but none seem to describe the problem this one has. When I got it the bottom quarter of the screen showed perfectly straight vertical lines in a random array of colors. The top 3/4 was fine (this was the reason it was discarded). After a short time turned on the next quarter up has joined the bottom quarter and now also shows the same banding (in perfect alignment) so its half good half bad now. No flickering or dancing around, but the bands are different from one time to the next when turned on. The other unusual feature is that when turned on the top half lights up instantly like normal but the bottom starts black but slowly the vertical banding becomes visible.

So far I've pulled out all the boards and looked for obvious toasted parts, and unplugged/replugged all the connectors. Nothing so far has made a difference. I'm assuming that since all parts of the screen eventually show light that there isn't a problem with the power supply, inverter board, or fluroecent tubes. I'm thinking of shooting some of the boards/components with hot/cold air. There are a few EL caps on the main board and the PS but not any on the screen interface board. None of the caps appear to be bulged but I haven't tested any yet. I haven't taken any pictures yet but the boards all look identical to the pict's posted on other threads related to this monitor.

I'm hopeing some of the guru's on this site can offer some clues, or ideas I can test to narrow it down.

Thanks
mjsbv

[mjsbv]

Re: HP LP3065 monitor half bad screen

Here is a pict's of the screen.

Thanks in advance for your help.
mjsbv

[Rtech]

Re: HP LP3065 monitor half bad screen

Replace the Screen...

[mjsbv]

Re: HP LP3065 monitor half bad screen

Update. I've managed to recover the quarter of the screen that died, but the bottom quarter is still elusive. The problem seems to be the horizontal scan data isn't making it to the screen. When I mess with the two flex connectors that go from the interface board to the screen I get varied results. The quarter that came back (and has stayed so far) did so after I cleaned/polished the ends of the flex. I got the bottom quarter to come up briefly one day when it was particurarly cold in the shop. If worked for a few min but faded out as the screen warmed up. I tried cold spray on the interface board and connectors but that didn't help.

[Lumberjack777]

Re: HP LP3065 monitor half bad screen

Here's a youtube video you might be interested in....
http://www.youtube.com/watch?v=purk_SyiT44

[mjsbv]

Re: HP LP3065 monitor half bad screen

That was an intresting video. Thanks for the link. I hadn't gotten around to taking of that part of the trim to expose the flex connectors to the screen, so I did that. There are 12 flex cables each with a chip attached to the back side. There is a pressure plate on the frame that goes over the top of them to put pressure on them, or act as a heat sink (not sure which). I pushed and prodded all of them with no effect on screen performance. Cold spray didn't matter either but the chips attached to the flex do get pretty hot. Hotter than seemed reasonable to me. I got out my O-scope and was poking about looking for signals that might be missing when suddenly a burst of smoke came rolling out. Always a bad sign, but the screen continued to work somewhat. After that poking on the flex cables did seem to make some difference and a couple more sections of the screen were intermittent. The smoke came from the interface board though not the cables or where I was poking around. I found a zener diode (ZD1) on the interface board that was smoked and now tests shorted. I wonder if the diode was going bad and finally let go or I shorted it out. Whatever its toast now. Here is a picture of the board with bad diode (circled in red), a couple larger shots of the board. Of course I cant read the lettering on it now. The last picture is of a similar board on a different thread that shows the diode but I still can't quite make out its lettering either. Any thoughts on what this zener diode might be?

Thanks
mjsbv