Shorted Cap In Scalar Board Caused No Display In SONY LED TV KLV-29P423D
This TV was picked up by me from one of my techie friends’ shop, as he sought my help to resolve an issue of no display, with VGH & AVDD missing. As he had already opened and cleaned the set, it saved my time.
Now let us have look at the scalar PCB and bit of inside for those who might be interested:
My techie friend, who always helps and guides me, told me to first of all isolate the concerned pins and its delivery end to the panel and check for any short either in the IC, Panel or that track.
I isolated the panel at the extreme end where it goes to panel and did not get a short in the panel. So rejoined it. Then isolated the track from the IC:
The short was traced to the rest of the track, which had series of SMD caps. In order to find out which was the culprit, my friend suggested applying 5V 5A to the track, after rubbing soldering flux on all the caps in the track. I saw one cap fuming when I did it and easily located it and removed it.
As you can see, it was reading 12.2 Ohms! I took one such cap of around 10uF and fixed it in the place.
Reconnected the tracks and applied power and was happy to see Sony logo displayed on the screen:
Fed my usual Video of Sherlock Holmes and allowed the TV to run for several hours before giving delivery to my friend.
Mission accomplished with double satisfaction gathered to the collection!
This article was prepared for you by Parasuraman Subramanian from India. He is 72 years old and has more than 30 years’ experience in handling antique equipment like Valve Radio, Amps, Reel Tape Recorders and currently studying latest tech-classes conducted by Kerala State Electronics Technicians’ Association. He has done graduation in BBA degree, private diploma in Radio Engineering and retired as MD of a USA company. Presently working as Consultant to Hospital and other institutions.
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