Question about Mag Innovision LT776s 17" LCD Monitor

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Display goes blank when brightness is above 70 percent

MAG 17 inch LCD Symptoms: 1: Monitor bulb stays on for a couple of seconds when power is turned on (to monitor) or when the display setting are changed from the control panel (from second monitor, running dual monitors). Example: if I change the refresh rate of the monitor it will light up for a couple of seconds. 2. I reset the monitor and this allowed it to stay lit for a small period of time but then problem returned. I then adjusted the brightness and found that the problem is related to this area. If I turn down the brightness below 70 percent it remains lit. The unit is about 11 months old. Is the bulb going bad? or the bulb controler? It is still under warranty so i should be able to have any repairs done for free. But the tech side of me wants to know what's causing this problem. Thanks for your help. Sincerely, Dean

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Re: Display goes blank when brightness is above 70...

This is a generic symptom that could happen to any LCD monitor.
The following is a generic answer applicable to most.

Two possible causes are bad capacitors or a bad light inside the LCD panel.

Open the unit and check to see if any of the capacitors in the power supply or other boards look domed or vented on the top.

Replace any capacitors accordingly. Use the same value capacitors. Most often, 1000uF 16V or 25V, 470uF at 16 or 25V, 220uF at 16V or 25V.

If this doesn’t solve the problem, try checking the surface-mount transistors on the inverter board that run the lights. Some times these transistors go bad. Check the area for any cracked or overheated ceramic or mylar capacitors.
Also, you may have a bad light inside the panel. This is tough to test without a spare light to use for troubleshooting.

You can take the panel apart and inspect the lamps but it is very tedious. It's tough enough to get them apart and back together again never mind keeping the layers clean. You have to try not to get any dust between the layers or you will see it in the picture.

There are usually two light fixtures each of which holds two lamps. One fixture is at the top and one at the bottom. Remove them one at a time and inspect the lamps to see if any are broken or very dark on the ends. If one looks out of place, it could be bad.

You'll have to find replacement lights on the net. It's not easy to replace them, but if you've gone this far, good luck. You should be able to get generic instructions off of the site that sells the lamps.

Posted on Mar 27, 2008

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