LG 60PZ750 running hot and maldischarged

[goldbird78]

Re: LG 60PZ750 running hot and maldischarged

Board still the same....I had a good friend who is an audio tech come over last weekend and check it out with me and there was no change in the wave form when we were testing. This could be because the board now acts maldischarge right away when I turn on the TV. The one thing I did notice a few times that is very strange is when the TV has been unplugged for 30-45 min and I put the board back I do get a small arc on one of the ground screws, this appears to happen when the screw driver touches the black heat sink and ground screw while installation (see pic). When I do the bub test with this board the buld are brighter than a good board that has no issues so that makes me that there is slight bleed to ground ? When the board is in without the bulbs it will not blow any fuses....I even went as far as replacing all the fgpf4633 IGBT transistors again in case I had a defective one. Below is a recap of what I have done so far.

Tested and Replaced all fgpf4633 transistors twice

replaced all gate resistors that were blown, tested and all read 13.5 Ohms in parallel.

Resoldered inductor coils twice, second time I even bridge the solder to the closest pads beside the coil points in case the the tracing was bad.

Resoldered the C142 small cap that is on the same trace.

touched up all solders on the heat sinks that looked poor.

any update on this? would be interested to see what you discovered.

[goldbird78]

Re: LG 60PZ750 running hot and maldischarged

Well what ever was giving the trouble finally popped the board again.....I put the board back in for further testing without the bulb test because it was not needed in the past and poof within 2 minutes smoked some of the transistors and gate resistors again. I am going to give it one more shot repairing this board......Tom you may see a board on the M6 real soon.....

any update on this? would be interested to see what you discovered.

[goldbird78]

Re: LG 60PZ750 running hot and maldischarged

SOLVED......OMG, it turns out the FGPF4633 IGBT transistors I was replacing were either bad or wrong. The originals were 1B39AX FGPF4633 and I was replacing them with 1G26CJ FGPF4633 which I got off of E-Bay, Is there a difference or did I just get bad E-Bay junk ?? See attached pic's, Right was the original's. Once again I want to thank Tom and others for there help and patience.

[freakaftr8]

Re: LG 60PZ750 running hot and maldischarged

I just repaired same board on a 60PV250. I got the 1B39AX. Works like a charm. Make sure you reflow the coils on the Y main too!

[goldbird78]

Re: LG 60PZ750 running hot and maldischarged

Yep, Did the coils on both boards.... These ran red hot from day one that you could not touch the heat sink for a second or you would burn yourself, and you could smell them running hot. Where did you get yours ?

I just repaired same board on a 60PV250. I got the 1B39AX. Works like a charm. Make sure you reflow the coils on the Y main too!

[freakaftr8]

Re: LG 60PZ750 running hot and maldischarged

I had that problem about a year ago with a 60PZ950. I have tried everything, could not figure it out why it was running so darn hot and malischarged. A lot of red fire pixels in the screen especially on scene changes from bright to dark. The heat sinks were extremely hot.


Gave up and ordered new board.


Got mine here.

https://rover.ebay.com/rover/0/0/0?m...2F282005586198

[freakaftr8]

Re: LG 60PZ750 running hot and maldischarged

Actually they are 1B51AH style. Sorry. I just went through 6 of those mosfets 3 on each heat sync. Also made sure I was reading 16 Ω between those resistors. Therefore I knew everything was good except for the 6.3 amp fuse that was blown. A couple of those solder joints for the coils were so toasted in roasted I that I had to bridge against the bottom of the board against the tracks to make sure that it was making a good connection

[goldbird78]

Re: LG 60PZ750 running hot and maldischarged

The first set of numbers/letters must be a rating. I got mine on E-Bay from China and I replaced them twice and it was still the same so I was not just a bad one in the batch. I robbed some from old boards and it works fine now..........I have been on this for 3 weeks!!

Actually they are 1B51AH style. Sorry

[freakaftr8]

Re: LG 60PZ750 running hot and maldischarged

The more we know. Lol

Underrated parts from China. Heard of this with the Panasonics too.

[tom66]

Re: LG 60PZ750 running hot and maldischarged

To be fair I think I remember the same issue on a PS43D450 Samsung I tried fixing...waveform was quite poor due to the transistors being shit. Strange it was intermittent, though.