Shorted LED Driver Mosfet In Hisense LED TV Repaired
Customer sent in this 24″ Hisense LED TV with the complaint of front Red LED light blinking. Red LED light blinking usually is due to problem in the mainboard (secondary side area ) or even in the power supply unit itself.
When I checked on the power supply output voltages, I found that the voltages fluctuated. It can be the problem in the power supply itself or something shorted in the mainboard also can cause the output to fluctuate.
This power supply has a built in LED driver circuit and when I flipped over the board, I found some of the section were affected-see the photo.
It does not look like electrolyte from electrolytic capacitor. Probably due to water entered (probably cola) and short circuit the board.
After cleaning the board with IPA, I checked on the LED driver Mosfet. It was found to be shorted-see the photo below:
Checking on other corresponding components did not find any other shorted parts so I took out another working Mosfet from a junk LED TV and fixed in and powered it up.
There was no more LED blinking and the Hisense logo immediately appeared in the screen-see photos below:
Conclusion- Assuming if the output voltages from the power are good and the power Red LED light still blinks this could means one of the memory ICs data could have corrupted. Of course you need to make sure that the memory ICs are receiving good DC supply voltages. For your information Damon Morrow just launched his latest ebook “Secret LED TV Solutions Volume 1 and you can check it out Here.
This article was prepared for you by Suranga Bandara who owns an Electronics repair shop in Anuradapura, Sri Lanka.
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