Sorry but this will be a long post.
PART 1
Let me point out that these are two sets with different models but both using the same suspect board (DELTA EADP-130BF A), the inverter/power supply board. Also for completeness let me specify that a different board (Darfon, forgot the version) is sometimes used in both of these models, which usually blows the transformers. This is not the case with these Delta boards.
Both sets show almost identical behavior, except that one of them does rather intermittently while the other does it all the time. The behavior is that the TVs turn on, display the logo, then screen turns off for two seconds (normal in this design), then screens turn back on and turn off permanently after 2-3 seconds.
Here is what I've learned.
IT'S NOT THE LAMPS, AND IT'S NOT THE TRANSFORMERS.
The problem is located in the section controlled by the transformer that has the smaller heat sink. It's not the transformer being defective cause not only have I removed it and test it, I've also exchanged with one from the other board, not part of this suspicious area, and the problem continues to happen.
It's not problems with the lamps either, long story, but I've completely ruled it out.
I've checked the four ceramic **10J capacitors in that section and they're within specs.
I've also checked C261, **105j and it's also within specs.
What I have not done is mess too much with the tiny components on the bottom of the board in that section until I get some pointers from here.
I've also re-touched the solder on all around the transformers and the components around them.
Now, one important thing. In this board each transformer controls four lamps, through two lamps connectors. If I take a 47k 5w resistor and solder it to the lamps connector, with or without the lamps connected too, the set gets past the two seconds to black problem and works fine. This happens whether I solder the resistor on either of the two lamps connectors. This is how I found out that the problem is somewhat related to this location.
PART 1
Let me point out that these are two sets with different models but both using the same suspect board (DELTA EADP-130BF A), the inverter/power supply board. Also for completeness let me specify that a different board (Darfon, forgot the version) is sometimes used in both of these models, which usually blows the transformers. This is not the case with these Delta boards.
Both sets show almost identical behavior, except that one of them does rather intermittently while the other does it all the time. The behavior is that the TVs turn on, display the logo, then screen turns off for two seconds (normal in this design), then screens turn back on and turn off permanently after 2-3 seconds.
Here is what I've learned.
IT'S NOT THE LAMPS, AND IT'S NOT THE TRANSFORMERS.
The problem is located in the section controlled by the transformer that has the smaller heat sink. It's not the transformer being defective cause not only have I removed it and test it, I've also exchanged with one from the other board, not part of this suspicious area, and the problem continues to happen.
It's not problems with the lamps either, long story, but I've completely ruled it out.
I've checked the four ceramic **10J capacitors in that section and they're within specs.
I've also checked C261, **105j and it's also within specs.
What I have not done is mess too much with the tiny components on the bottom of the board in that section until I get some pointers from here.
I've also re-touched the solder on all around the transformers and the components around them.
Now, one important thing. In this board each transformer controls four lamps, through two lamps connectors. If I take a 47k 5w resistor and solder it to the lamps connector, with or without the lamps connected too, the set gets past the two seconds to black problem and works fine. This happens whether I solder the resistor on either of the two lamps connectors. This is how I found out that the problem is somewhat related to this location.
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