How to Troubleshooting and Repairing LCD Monitor Randomly No Display and No Power Problem

April 27, 2019

How to Troubleshooting and Repairing LCD Monitor Randomly No Display and No Power Problem

Model: Dell E152FPb LCD Monitor

Symptom: After 5 minutes or several hours power on the lcd monitor, it will no display and no power (no LED light).

This lcd monitor was sent by my friend with symptom no display randomly. Sometime it happened after several minutes or several hours! As usual, before open the lcd monitor, try to testing this lcd monitor first and it is working properly! So just leave it burnt test and after 2 hours, the problem occur. Before the lcd monitor become no display, i saw the power LED light blinking several times and the light off, after that, no display.

Do you know which section and components failure?

After opened the lcd monitor same as photos above, power on the monitor and starting measured the IP board output voltages, BL_ON signal and mainboard. All these voltages and the BL-ON signal are ok and stable. Even resolder all the bad soldering points also not help at all. When this lcd monitor no display problem came again, i try to testing all the voltages and signal points and found that this monitor is in the standby mode. Where you need to push the lcd monitor power switch to on it again, then it will came the exactly voltages.

So i guess it could be the mainboard MCU, Flash IC (or their firmware), crystal and the control panel/key pad. Then i try the easy step first, disconnect the control panel and direct power on from the main AC plug. LCD Monitor working properly and i continue to testing control panel board. Suddenly i found that 4 micro switch buttons, got 3 buttons were leaked. You can refer to the picture below:

The good micro switch button when you push it on, then you can get the 0 (Zero) ohm, when release it, then it is no value or call it infinity. I suggest that change all 4 micro switch together to prevent any return case.

After changed these micro switch buttons, this lcd monitor are working perfectly now!

Conclusion: Actually changed these components are easy but it is hard to find out the culprit! So you need to know how LCD Monitor working and the knowledge of troubleshooting & repairing LCD Monitor!

Enjoy Repair!

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