Question about ViewSonic VG800 18" LCD Monitor

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Thanks I used your solution to repair 24 bad Viewsonic 19" flatscreens. We had 28 bad and 24 were due to the bad cap. The others come on for like 1/10 second then turn off. Problem follows the LCD panel not inverter or power board.

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  • frank_drebin Mar 27, 2008

    No, what I mean is, I swapped a known good power/video board and the problem persisted. I then swapped the inverter board, same problem. The problem was in the LCD itself. I used the other boards (with the new caps) in other monitors with no problem.

  • frank_drebin Mar 27, 2008

    Yeah, these are my parts machines now. Thanks for your help though. Saved us a ton of money. I hope these last a few more years now. I also had 10 Samsung Syncmasters that wouldn't power up and fixed them as well. They each had 3 bad caps and a bad fusable link on the 13v power supply.


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Without having it in front of me to test it's tough to tell. Sounds like a power supply problem, the shotgun approach would be to just replace all the electrolytics and see if that fixes the issue starting with the ones closest to the power input.

This is a VG800 right? Because the power supply and video boards are integrated on the monitor, so you can't really narrow it down between the power or video side of the board (you can unplug the inverter, but it sounds like you've already tried that). Since the power button is just a soft start button (the monitor always has power once it's been plugged in) you can try troubleshooting the parts of the board that are constantly energized and figure out where the power is switched on by the soft switch, that may be helpful.

Posted on Mar 27, 2008

  • Chris M
    Chris M Mar 27, 2008

    Ok, that makes more sense then, I was wondering what you meant.

    So the LVDS signal that is sent off of the main board is sent up to another circuit behind the screen itself. There must be an issue on that circuit. If you take the panel itself out of the cradle there should be a small metal panel that is screwed onto the back of the screen itself. If you remove the screws and carefully flip the metal guard forward you should see the circuit that actually sends the signals to the individual transistors on the screen itself. I'm wondering if something isn't shorted to the panel chassis up there and causing the panel to shut off. The trouble there is that the circuitry on the back of the panel is all very tiny surface mount components which are very difficult to work on so unless it's something obvious. I don't really have any more ideas :) You might want to keep those four as backups since you have so many of those monitors around if you can't come up with anything.


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