40 inch Samsung LED television model UA40J5000AK dead now repaired!

I received a call from a client who wanted his television checked by a technician.

It was within the estate, so using the direction he gave I was able to locate the place effortlessly.

Upon reaching the place, I was shown the television, applied the power and indeed the television was dead, even the power ON led was off.

I opened the television and did scanning on both power and main board and could not see any suspect’s area or component.

I pulled my meter and tested the main fuse and to my surprise I found it okay.

With that I now decided to do proper troubleshooting, first let me point out here that dead symptoms in television(LCD-LED) can be caused by power supply failure or main board failure.

From my analysis I concluded the problem was on the power  board and therefore begin doing sample testing on components especially for short.

Since the fuse was intact I could not suspect shorted component on the primary side since shorted component on the primary side will lead to instant blow to the main fuse.

So I begin testing output component like diodes and transistors which failure rate is quite high.

Testing for shorted components in circuit is okay but if you find a beep, it is always important to solder one pin out of the circuit to confirm the actual culprit.

As I continued testing secondary output components I got a beep across a diode and I wanted to be sure if indeed it’s a beep on just low capacitor resistance reading before charging.

In my case the beep continued and this put a smile on my face, this could be the culprit.

I soldered the two diodes that had beep out of the circuit and found one was dead short.

Since I was working on site I had to go back to my shop because I did not have this diode (FR) with me.

This time I decided to carry with me the whole board for further testing once I replace the faulty diode.

Back in the shop I salvaged the diode from a junk board which had same specs with the one which was faulty, after replacement I tested the board and noted the standby voltage was present and stable.

I went back to the client place hoping for the best and after re-installing the power board, I applied the power and I noted the backlights were on since the television was placed back up.

This put a smile on my face, this is the final results.

Thank up guys

See you in the next class.