LG Plasma 50PA5500. Sound, no picture !!
Sorry if this is too repetitive, or in the wrong place.
I'm new, and having much the same problem. My LG50PA5500 TV has been working flawlessly since new. The other day, while in the midst of watching a broadcast DTV channel, the entire screen suddenly and silently went dark (no snaps, crackles or pops); sound, channel selection and inputs all work OK.
I have checked connections and voltages from: stdby, pwr supply board fuses, psb output voltages to Zsus board and its fuse, output voltages from Zsus to Ysus and its fuse. All precisely normal!! I've also checked voltages to the other control boards, etc.
No indications of cap problems, though they will need to be tested with tester in tomorrow's mail. Also a transistor tester coming.
The ONLY slight indication of anything amiss, is a (what I would call!!) light "toasting" (no pun, sorry) about 1.5" in irregular diameter towards the center from the copper coil of the Ysus board. I almost "feel" that that would be consistent with fair wear and tear of 9 years use, but of course, heat is the eternal enemy of electronics. I have very closely examined both X and Y boards, front and back for any damage indications.
I have not yet touched the Y buffer boards. If that is the next step, what is it that I should check and the sequence to follow????
I'm kind of at a standstill, and need some direction before I start swapping out boards left and right. Any help would be greatly appreciated. Thanx
FOLLOW-UP: I've tested the E-caps on the unmounted Ysus board, with mixed results, using both a DVM cap testing as well as an ESR meter; some good, some borderline, some bad, but all tested in-circuit. The tests, along with the discoloration on the board, are leading my naive judgement to suspect a bad Ysus board- maybe more than one bad component on it.
I removed the Y buffer boards for a CLOSE visual inspection; all looked good- way better than the Ysus board, with its apparent 'toasting'. I inspected the 8 ribbon cables and find no evidence of rubbing, etc, as discussed elsewhere. I did remove both Y buffer boards, and checked them for grounds (at ribbon output connections). I have not checked the resistance/voltage across the VSC-r273 and VY-r272 resistors. I'm not sure how to configure everything first, nor what I'm looking for, as has been commented on elsewhere.
When looking at the whole boards "picture" from the back of the TV, it is apparent, that the only discoloration/overheating, is on the Ysus board, but I can't seem to find, or even know how to find, a "smoking gun" which would explain the sudden complete loss of picture.
I've been reading through all the posts, bit by bit (!!!), trying to gather info from all you guys expertise. Any help you can offer would be most welcome. I think if I can get the display back to normal, I'll still have a great 1K plasma for a couple more years, until the OLEDs come down in price!! Please help if you can. Thank you very much.
I'm new, and having much the same problem. My LG50PA5500 TV has been working flawlessly since new. The other day, while in the midst of watching a broadcast DTV channel, the entire screen suddenly and silently went dark (no snaps, crackles or pops); sound, channel selection and inputs all work OK.
I have checked connections and voltages from: stdby, pwr supply board fuses, psb output voltages to Zsus board and its fuse, output voltages from Zsus to Ysus and its fuse. All precisely normal!! I've also checked voltages to the other control boards, etc.
No indications of cap problems, though they will need to be tested with tester in tomorrow's mail. Also a transistor tester coming.
The ONLY slight indication of anything amiss, is a (what I would call!!) light "toasting" (no pun, sorry) about 1.5" in irregular diameter towards the center from the copper coil of the Ysus board. I almost "feel" that that would be consistent with fair wear and tear of 9 years use, but of course, heat is the eternal enemy of electronics. I have very closely examined both X and Y boards, front and back for any damage indications.
I have not yet touched the Y buffer boards. If that is the next step, what is it that I should check and the sequence to follow????
I'm kind of at a standstill, and need some direction before I start swapping out boards left and right. Any help would be greatly appreciated. Thanx
FOLLOW-UP: I've tested the E-caps on the unmounted Ysus board, with mixed results, using both a DVM cap testing as well as an ESR meter; some good, some borderline, some bad, but all tested in-circuit. The tests, along with the discoloration on the board, are leading my naive judgement to suspect a bad Ysus board- maybe more than one bad component on it.
I removed the Y buffer boards for a CLOSE visual inspection; all looked good- way better than the Ysus board, with its apparent 'toasting'. I inspected the 8 ribbon cables and find no evidence of rubbing, etc, as discussed elsewhere. I did remove both Y buffer boards, and checked them for grounds (at ribbon output connections). I have not checked the resistance/voltage across the VSC-r273 and VY-r272 resistors. I'm not sure how to configure everything first, nor what I'm looking for, as has been commented on elsewhere.
When looking at the whole boards "picture" from the back of the TV, it is apparent, that the only discoloration/overheating, is on the Ysus board, but I can't seem to find, or even know how to find, a "smoking gun" which would explain the sudden complete loss of picture.
I've been reading through all the posts, bit by bit (!!!), trying to gather info from all you guys expertise. Any help you can offer would be most welcome. I think if I can get the display back to normal, I'll still have a great 1K plasma for a couple more years, until the OLEDs come down in price!! Please help if you can. Thank you very much.
