Repairing Electronic devices
Repairing defective electronic devices
I have successfully repaired some electronic devices, mostly for my own use. The most interesting repair job that I have done is a 50” LCD-tv. Tv repairs are interesting if the screen is still intact. For example, if a tv won’t turn on but the power led is blinking, it most certainly has a defective power supply.
So when I opened it up it was obvious that there was something wrong with the power supply because of a visible blown capacitor. Just replacing the capacitor was not enough. I learned that a blown capacitor means that something in this circuit caused it to blow, therefore it is not the cause of the problem but a result of another defective component
I took my time to do some reading into Switch Mode Power Supplies, and learned that the blown capacitor was part of the power factor correction circuit. I tested all components within this circuit with a multimeter (FLUKE 117) and a cheap Chinese multi-function tester. I had to desolder some components in order to test them properly. Eventually I found out that the circuit contained a faulty MOSFET and a faulty diode.
To remove the MOSFET I had to desolder an entire heatsink containing 2 other MOSFET’s. I damaged some pins while doing that I had to replace them all.
After replacing these components, I screwed the power supply back on the TV and plugged in all the cables back on the board. I powered it on and it worked like a charm!