First post on a problematic tv for me, also my first plasma.It is a nexus nx502 using the lg pdp50x3 panel, it uses an advent 667phst18-200 power board. I received the tv from the original owner after it made a loud bang and quit working.
I opened it up expecting to find some blown capacitors and indeed there was one large 330uf filter cap with the top vented. The fuse was still good so I ordered up two new Panasonic caps to replace the filter caps. After soldering in the replacements I tried to turn on the tv only to have a 100pf multilayer ceramic bypass cap explode as well as the chopper ic strx6769 and of course blow the fuse. I found replacement parts and soldered them in. The set passed the light bulb test turning on for a second then back off. I applied a new fuse and plugged in the set (fuse ok) when I hit the power button I got to watch my 15$ ic explode.
All the secondary side components are testing ok, I was thinking maybe its something that only breaks down when fully powered up
I have ring tested the primary and secondary of the switch mode transformers and they are ringing ok. With the strx6769 out of circuit I get my 5v, 12v and 3.3v on my main board. As far as I can tell this means the strx6769 provides my vs and va voltages only. Can a short on a different board drag enough current across the chip to make it explode or
should I still be concentrating on my power board as the main culprit? My new str chips should be here today and I can continue trouble shooting after they get here.
I have the following test equipment-Oscilloscope, multimeter, capacitance meter, esr meter, ring tester, and my trusty light bulb. I can shoot more pictures later but here is the power board from shopjimmy. The strx6769 is the chip about dead center in the board.
I opened it up expecting to find some blown capacitors and indeed there was one large 330uf filter cap with the top vented. The fuse was still good so I ordered up two new Panasonic caps to replace the filter caps. After soldering in the replacements I tried to turn on the tv only to have a 100pf multilayer ceramic bypass cap explode as well as the chopper ic strx6769 and of course blow the fuse. I found replacement parts and soldered them in. The set passed the light bulb test turning on for a second then back off. I applied a new fuse and plugged in the set (fuse ok) when I hit the power button I got to watch my 15$ ic explode.
All the secondary side components are testing ok, I was thinking maybe its something that only breaks down when fully powered up
I have ring tested the primary and secondary of the switch mode transformers and they are ringing ok. With the strx6769 out of circuit I get my 5v, 12v and 3.3v on my main board. As far as I can tell this means the strx6769 provides my vs and va voltages only. Can a short on a different board drag enough current across the chip to make it explode or
should I still be concentrating on my power board as the main culprit? My new str chips should be here today and I can continue trouble shooting after they get here.
I have the following test equipment-Oscilloscope, multimeter, capacitance meter, esr meter, ring tester, and my trusty light bulb. I can shoot more pictures later but here is the power board from shopjimmy. The strx6769 is the chip about dead center in the board.
on a better note I was testing the board off chassis and noticed it was acting differently. Low and behold I have my vs voltages as long as the ground screw isn't tied to the chassis. It only grounds in one spot on the primary and one on the secondary. So I am gathering that one of my components is shorting to ground in the secondary. I am only uploading the first 3 pictures today, I will upload the rest when I get on a faster internet connection.
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