dell lcd monitor repair

No Power In Dell E176FPb LCD Monitor Solved!

The moment the cover had been removed I saw 6 bulged electrolytic capacitors at the secondary side. Two of them were 1000uf 16 volt and the other four were 470 uf 35 volt.

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For your information the main fuse did not blow. The question now is why the electrolytic capacitors became bulged? There are three reasons for it:

1) Bad components in the primary power supply side especially the big main filter capacitor.

2) Over voltage caused by defective component in Optoisolator IC circuit (secondary side)

3) Low quality of Electrolytic capacitors were used

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Judging from above the first thing I do was to check if there are any bad component in the power primary side. Upon careful inspection, I saw the main filter capacitor one of the leads already corroded due to the leakage of the internal electrolyte. Testing it with my Blue ESR meter shown a slightly high ESR ohm.

Note: Even if the main capacitor is tested good with Blue ESR meter you also need to directly replace it because if you didn’t, I believe in few weeks to few months time the problem in the cap will arise and cause the Monitor not to function again. In worst case, it could blow up the components in power section!

I did not check on the components in the Optoisolator IC secondary circuit because I believe the main cause of why the 6 electrolytic capacitors bulged was because of the main capacitor. After replacement with the 7 Electrolytic capacitors the LCD Monitor worked like charm again.

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Tip: Assuming if you want to check on the Optoisolator IC circuit pay special attention to the resistors value. A higher than normal resistance value in this circuit could cause all the secondary output voltages to increase thus all the electrolytic capacitors will burst or becomes bulge. Check also to see if the phototransistor in the Optoisolator IC have leakage or open circuit.

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