Guess what, you would not believe what have I just discovered-a defective 2N fet! A defective component in either primary or secondary side could cause low output voltage. I could not believe it was this faulty fet that causes all the output voltages to drop! If the LCD monitor designed to run on 18 or 24 volts then you could use a light bulb from the big trailer. Removing the cover was a bit easy compared to other models. However this monitor boards looks perfectly okay.
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Dell Computer Monitor EFPb User Guide |
When the power is on the light bulb still do not lit and the sound still could be heard. If the LCD monitor designed to run on 18 or 24 volts then you could use a light bulb from the big trailer.
You could use this method but first you must confirm that the secondary filter capacitors, TL adjustable precision shunt regulator ic, optoisolators and components surrounding the optoisolator is working before you proceed to use the light bulb. After checking all the components I was surprised that all of them tested okay.
Since I had checked all the components and could not locate the fault, the only way that I could do is to direct replace the semiconductor devices such as the diodes, scr, fet, and transistors. From experienced I do encountered semiconductor components breakdown when under full operating voltage.
Dell E151FPB LCD Monitor
This is the time to really test your basic electronics skill because you now know at which area the fault is and you just have to use your skills to locate the exact bad component. Plasma TV Repair Ebook. Removing the fuse as shown in the photo and connect the bulb between the supply line and the cold ground could tell which section is giving problem.
Dell Efpb LCD monitor came in with the complaint of no power but upon carefully look at the LCD you could see a very light blur white flashes across the screen and the power LED is not lit.
Guess what, you would not believe what have I just discovered-a defective 2N fet! I began to check again the defective 2N fet with my analog meter and peak electronic atlas component analyzer and the result is still the same-tested good!
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However this monitor boards looks perfectly okay. E1151fpb I measure the 12 volts line with a monitoe multimeter, the readout was about 7- 8 volts which was very unusual. One by one of the semiconductor components I replaced and power on each time I had changed it to see if the bulb light up or not. Now we could use a 12 volt automobile brake light bulb to test at which section that is causing the low voltage output problem.
It was quite challenging to troubleshoot this kind of problem where you are hundred percent sure that the primary side is giving problem yet you could not find out the culprit.
What you have just learned from here was that if all the suspected components tested good, the only way to reveal the truth is to direct replace the parts. The moments I have replaced this fet and power on, the bulb immediately light up. Hope you enjoy this article and more good articles to e151pfb everyday! I could not believe it was this faulty fet that causes all the output voltages to drop! Just like flyback transformer, the best testing equipment to test Fet and other components is actually the equipment itself because it runs on full operating voltage, frequency, signal and etc.
As usual whenever the mainboard and power board were exposed, I would look for any bulged capacitor, darkened area, a loosen connector and etc. In fact this is good news to us because we know what the next step that we should make.
Wishing you all the best and happy repairing! There were not much components in the primary side, and you could easily check all of them in less than 20 minutes. How To Test Electronics Components.
A defective component in either primary or secondary side could cause low output voltage. Removing the monitorr was a bit easy compared to other models.