Troubleshooting DELL E173FPB LCD monitor with power flickering symptom is quite easy if you know the correct procedure to test it. There are two sections on the monitor that can cause the power to flicker. Is it a primary or secondary section or even sometimes both sections can be faulty. So to isolate which section is giving you problems. I used an automobile 12 volt light bulb (brake light) and wired it between the 12 volt supply line and cold ground with the fuse removed. If the bulb continues to blink, it is most likely that the primary power section has a problem.

Do not bypass the line for other voltages, such as 3.3 and 5 volts. If any component is shorted to the 5 and 3.3 volt supply, the power may also flicker. If the 12 volt bulb lights up, we can assume the power supply is working fine and there is a short further down the line causing the power supply to flicker. If the bulb lights up and you continue to check the power section, you will waste your time. Now you need to focus on the circuitry in the secondary section, such as the four C5707 transistors that drive the high-voltage transformer on the inverter board.

Just think of these transistors as the horizontal output (HOT) transistor in the CRT monitor that drives the flyback transformer where you worked so hard and the chances of it failing are very high. Upon checking the four transistors off the board, it was found that one of them had a shorted reading with an ohmmeter. of the four high voltage transformers verified to be ok with ringer and ohmmeter test.

Now, here is the secret that I am going to reveal. If you only replace the faulty transistor, it is very likely that the transistor or another C5707 transistor will fail again. Typically what a technician does is test the other transistors with an analog or digital meter. If you use both meters to test the transistors then you have missed the faulty transistor because both meters will not give you the true reading of the transistors. Only some digital meters have hfe check function. In other words, you need to test the hfe reading of a transistor. Although you can replace the other three transistors directly, why don’t we do some detective work to find the cause of the problem?

Using the Peak electronic atlas component analyzer, I was able to clearly see the difference between a good transistor and a bad one. A good C5707 transistor has a lifetime reading of 320 to about 390, but the bad one reads 467! The other two C5707 transistors have a reading of about 350. In the above case, only two C5707 transistors were replaced and the other two are saved. I had this LCD monitor burn in test for many days and it worked perfectly fine.

Conclusion: Whether you are repairing DELL E173FPB LCD Monitor or any other model, such as E172FPB or E171FPB, basically the testing method is the same. You can also use this test procedure on another brand of LCD monitor.