Question about Computers & Internet
Starts the screen and it shows the background image for 1 to 2 seconds then the picture becomes black. Start it again and it does the same thing again. I have opened the screen but do not see any capacitors that are clearly broken. Could it be the mainboard? Or should I replace all capacitors on the psu anyway?
First if you can, try the monitor with other PC first to make sure it is not the PC problem.
If it behaves in the same fashion, then most probably has dying power supply due to bad DC filter caps, just see the top side of the caps to ensure it has not bulged up distorted.See the images bellow
Then there is the logic board. Plug the monitor in but do not activate the power switch so the backlight inverter circuits will be off. Check the 5vdc and the 12~24vdc to make sure they are OK. They should be tested with the load, you can use 6V 1A (6watts) lamp for the 5vdc, and car lamps such as 1157 (12v 8watts lo/26watts high) turn signal brake lamp using high filament connection for testing the 12~18vdc (or use two 1157 in series for 19~24vdc) for the backlight inverter circuits.
If the power supplies are working, the output voltages should be steady at the rated voltages. The power supply will go into shut down if it detects too much current draw due to false in the power supply or short circuits in the backlight inverter or in the logic board.
The backlight inverter circuits:
It takes the 12~24vdc and converts it to high frequency AC to drive the inverter transformers CCFL (Cold Cathode Fluorescent Lamp) assemblies. The transformers will drive the CCFL by applying the start up voltage (around 1500~2000v), when the CCFL start conducting, the voltage will drop down to about 500~800v.
The inverter has detection circuits to detect open circuit if the lamp is not attached or does not fire up after the start up voltage is applied, it will go into shut down. It will also shut down if the lamps draw too much current due to ages (when lamp gets old it will draw more current).
The inverter gets two signals from the logic board, one is the backlight ON/OFF signal, the other one is the Dimming signal for the lamps.
Bad filter caps, resonant caps (in the inverter output circuits), blown transistors/IC, shorted or open transformer winding.
If you are confident with your skill then go ahead else go to an authorized outlet for repairing
Do write back if you face any difficulty while working on the monitor
Posted on Dec 24, 2012
I have the same problem with a customer's monitor (LT716S); it turned out to be damaged power supply board. As I understand it, MAG has a 3 year warranty on parts, will probably charge you a flat labor fee plus shipping. If you do not have your purchase documentation for warranty, dump it and replace. If you can, then you may wish to have it repaired.
My customer replaced theirs; I am trying to purchase replacement parts to repair...good luck.
Posted on Feb 25, 2009
Yes, It sounds like the backlight inverter circuit is shutting down. No inverter power, no backlight. On some monitors the inverter circuit will shot circuit the power power supply which makes the power light flash on some it just kills the backlight. You can usually check with a flashlight. Hold the flashlight pointed at the screen and see if you can see any of the icons or background picture. If you can then it is the backlight circuit or backlight tubes, usually the circuit.
Posted on Jul 24, 2009
Tips for a great answer:
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Aug 04, 2011 | Computers & Internet
Click the picture or color that you want to use for your desktop
If the picture you want to use isn't in the list of desktop
background pictures, click an item in the Picture location
list to see other categories, or click Browse to search
for the picture on your computer. When you find the picture that you want,
double-click it. It will become your desktop background.
Look for pictures in other locations on your
Under Picture position, click the arrow and
choose whether to crop the picture to fill the screen, fit the picture to the
screen, stretch the picture to fit the screen, tile the picture, or center the
picture on the screen, and then click Save
If you choose to have a fitted or centered picture as your desktop
background, you can also frame your picture with a color background. Under Picture position, click Fit or Center. Click Change background color,
click a color, and then click OK.
To make any picture stored on your computer (or a picture you are
currently viewing) your desktop background, right-click the picture, and then
click Set as Desktop Background.
The Set as Desktop Background option
Apr 24, 2011 | Computers & Internet
Jan 30, 2011 | Computers & Internet
You can right click on the picture itself and select "set as Desktop background"
Click on the Start menu button. Then click on Settings and then on Control Panel.
Double-click on the Display icon or text link. This will open a window named Display Properties.
Click on Background if that tab is not selected. Click on one of the items that appear in the box labeled Wallpaper.
Inspect the preview that appears above the Wallpaper menubox. Use the Display menu to the right to experiment with tiling, stretching or centering the picture that you are previewing.
Click on Browse to use an image stored elsewhere on your hard drive. Locate the image and click Open.
Click OK to change your background, or wallpaper. Click Cancel if you decide to maintain your current settings.
Click on this link or copy and paste the complete link into your browser.
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