Dec 20, 2017, 5:53 PM
Post #1 of 2
I'll try to make this short as possible, but I want to be thorough:
LG plasma 60PK750 - suspected y sustain issue, replaced, still broken..?
Background-A few weeks ago, my wife reported to me that our LG 60" plasma (model 60PK750) that we have had since 2011 was having an issue with the picture flashing and going in and out. That night, I did some research, and read it was likely a bad Y SUS or Y Buffers. A day later, the screen stopped working entirely. Now, when you turn the TV on, the screen goes dark grey from black (indicating the tv is turning on), then simply goes black after a second. You can hear sound, but nothing works, just a completely dark screen (no menu function or anything).
I purchased a used Y SUS board and both Y Buffers from Ebay which were reportedly pulled and tested as working from a new (though damaged in shipping) LG 60PK750. The seller gauranteed the boards were fine, and I assumed after all I read, that installing them would fix my issue.
Fast forward to yesterday, I received the boards in the mail, and first started with installing the Y SUS to see if the issue was with the Y SUS and not the buffers (so I could rule the buffers out and resell them). When I switched out the Y SUS, plugged everything up and turned the TV on, the screen showed a couple of white lines across the top horizontally, but the rest of the screen was still black (not that this is different than what I had with the original Y SUS board). I thought that the buffers must be bad, so I proceed to switch out the buffers as well. When I got all three new boards installed and turned the TV on, the same issue (white lines across the top of the screen).
I decided to try some troubleshooting, so I unplugged the upper Y Buffer as the internet instructed me to do, and the only change was that the white lines moved to the middle of the screen. I plugged the upper back in, and unplugged the lower, and half of the screen turned light grey (the bottom half IIRC, but I could be wrong). I then reinstalled the original Y SUS (leaving the new Y Buffers in), plugged everything in, and my original issue of the screen going dark grey, then turning completely black came back (no white lines on the screen as with the new Y SUS). I did one last test of unplugging the Z SUS, and there was no change whatsoever (black screen). Under all conditions, there was sound.
So I decided to put everything back the way it was (reinstalled all the old boards), and here I am wondering where I can go from here. From the sounds of this, is my issue somewhere else? Did I get faulty boards from Ebay? (seems least likely, though possible of course). I'm not an electronics expert, but I do have a multi-meter, but I would need to be walked through where exactly to test.
We already bought a new 65" Samsung curved LED, but we paid $1500 for this thing 6 years ago and had hoped to fix it for cheap and use it in our kids playroom. I hate to throw it away especially after dumping $90 into it for new Y SUS and Y Buffers, but I'm not willing to put another dime into it unless I can do some tests and have someone on here say with at least 95% certainty my issue likes in _______.
Any input you can provide would be amazing. Again, I'm 100% willing to do some tests, but I need some guidance.
**NOTE: When I installed the new boards, I didn't screw them down completely. I don't think this would matter, but thought I should mention it. Not sure if screwing them down to the TV frame maybe has something to do with grounding them or not, but I wanted to make it easier to remove them if needs be, so when I was installing and plugging the new boards in I didn't tighten them down (just put a couple screws in to hold them in place).
Also, I looked at the strips that plug from the screen (i'm guessing that's where they come from) into the Y Buffers and reseated them multiple times as I heard that a bad connection in these electrical strips can cause issues, and they seemed to be well seated.