DGTEC DG-FV42LCD solarises

[maxvalutech]

Got this set some months back in a disassembled state and "picture problem". Just got to a it now so reassembled all again - it is a nuisance type set with inverter and tcon on main body and PSU with main inset in back panel. All went OK so fired it up but as I don't have normal broadcast TV had to use satellite box input. To my surprise set went well with a good picture which I monitored for around 40 mins then left it going just checking every now and then. After about 90 mins on the picture suddenly started to solarise and that got worse and worse as bad as I've seen. Turned set off waited 10 seconds and switched back on to find no solarization but jerky bits (image retention?) in parts of picture here and there. Very unusual but must be tcon , surely ???
No pics set still sewn up for further tests at this time.

[steviewonder]

Re: DGTEC DG-FV42LCD solarises

Yes,I would say Tcon too,had similar issues to yours in the past,But saying that,also had a Toshiba set recently with the same issues,that turned out to be a tab bond issue..

[maxvalutech]

Re: DGTEC DG-FV42LCD solarises

Thanks for input Stevie. Took this set apart again to get the tcon board number and give it a good going over and clean up. Also undid and cleaned all connectors and carefully reseated them. With checking of gamma voltages in mind reassembled the set but without tcon metal cover. Also, on a whim, while tcon out I laid that board down on white concrete base in the full sun. Where I am at this time the climate is similar to desert conditions, coldish nights very hot days. The temp was 33C (91F) in the shade and left the board to "cook" for about an hour. Well, so far, the set has had test runs with DVD on AV in 3 to 4 hours stints and no problems evident. Will continue testing and see how it goes....here's hoping!

[maxvalutech]

Re: DGTEC DG-FV42LCD solarises

As above ran this set now for many hours and no problems at all so confidently undid enough to replace metal cover over tcon - this meant taking lvds out of tcon connector and a few leads on main board. Put it all back together and turned it on with DVD attached - yes you guessed it solarization immediately. Now could the tcon cover plate be interfering with something ? It does go over the screen leads as well. I imagine the plate is there to repel rf interference ? I'm now going to try again with it left out of the set. Anyone had problems with these cover plates before??

[Andrew F. Ali]

Re: DGTEC DG-FV42LCD solarises

Are you absolutely sure you are installing the metal cover correctly? It would seem that the FFC/s to the Panel Bd/s or the LVDS cable from the Main Bd. is being distorted some how. The metal cover also acts as a heatsink as you may see heat conducting rubber on the ICs that press on the cover when it is secured in place. I think leaving the T-CON in the sun did nothing really but heat up the board. At 33C that is not hot enough to melt solder or anything.

[maxvalutech]

Re: DGTEC DG-FV42LCD solarises

Thanks Andrew F. Ali and yes I'm sure the plate went in correctly as it has a flange going over the top of the frame with two locating tabs into the frame - no contact with tcon other than sharing the 4 holding screws. Seems more like a heat trap really rather than sink! The heat here in direct sun is much more than shade measurement - years ago I left a large thermometer out in the open while working and when I remembered it found it burst open unable to take pressure from the mercury fill. But the reason for leaving the tcon out was just to see if it hastened anything either good or bad. My reasoning being why did it take so long for the fault to show? A heating problem should not take that much time. So reviewing what I did in final assembly of the set, being remove a few connections including lvds from tcon, putting in cover plate being careful not to disturb screen leads etc, replacing connections, and putting rear panel on, the most likely suspect other than an intermittent was the lvds. Took the rear panel off again and closely looked at lvds in tcon, did look as if slightly down on one side so removed it and then put it in/out/in a few times - a definite looseness or very slight wobble evident so reconnected test DVD after tightening the connection as best I could. Picture again going OK for around 40mins so far. Moving set from workbench to test area could have affected lvds connection in earlier test. Time will tell.

Given the fact that all our planets plus sun and moon are round does that tell us something?


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[maxvalutech]

Re: DGTEC DG-FV42LCD solarises

Yes I did wiggle tcon connector when DVD first on but all OK then. Just did that again after 60mins running and instant solarization so have now reseated and taped it all. Why now not earlier well the tcon connector was very very hot but not from the board but from the set metal back which was too hot to touch. I think the connector just expands from this heat buildup. For info today is mid autumn here but our temperature will peak shortly at 38C (100F) whereas this time next week is forecast to be 23C (73F). These extremes bring their own problems as well as the usual ones.

[maxvalutech]

Re: DGTEC DG-FV42LCD solarises

Have run this set now for many hours and no solarization but another problem has become evident. After 6/7 hours the set suddenly loses picture, audio, backlights but it does not go back into standby as the blue light remains on. Turn it off then on and it goes OK again for another couple of hours then does the same again - no noise or indication beforehand. I suspect PSU so will give it a good look over.