Hi folks. This panel seems to be a 'favourite' on these forums. I've checked through all the existing posts and my issue doesn't match up with the common faults described. I think it might be the logic board.
I acquired it second-hand recently and the previous owner described the panel working fine until a power cut, when it only turned back on briefly. The apparent issue was that, when powered on, the TV would display the manufacturer logo and then go into standby mode. I figured this was the main board shutting it down after a test condition failed.
I checked the capacitors and found that all the 100uF, 100V caps had blown their arses out. Replace them and tried again - same problem. No other visual problems are apparent. (Note: the user was a heavy smoker and I have had to clean the boards and chassis from top to bottom - the same problem existed before and after I cleaned everything.)
I did the usual steps of measuring voltages (all good) and unplugging boards in sequence and none of this made a difference. I then desoldered and checked cap C802 because of the sheer amount of reports that this goes bad, but it was absolutely fine.
Something changed around this point. Now when I plug it in, I don't get the LG logo anymore, just some momentary snow before there is no image (and no sound - there never has been), but the panel is 'on', instead of going into standby like before. The Y-SUS board is making some noise when powered, but not when the unit is off or in standby. Also, the red light on the main board is lit.
I have tried the AUTO_EXT_GEN test pattern feature and no picture is produced, though it does alter the sound coming from the Y-SUS board. There is a green light on the logic board, which is displaying what looks like an error code (one long dash, one short dash, repeated once) but I have no documentation to refer to (the service manual appears not to include such codes).
Any ideas?
p.s. I've noticed a common factor people discuss with this panel is clicking relays - mine appears to be a revision that has no relays.
I acquired it second-hand recently and the previous owner described the panel working fine until a power cut, when it only turned back on briefly. The apparent issue was that, when powered on, the TV would display the manufacturer logo and then go into standby mode. I figured this was the main board shutting it down after a test condition failed.
I checked the capacitors and found that all the 100uF, 100V caps had blown their arses out. Replace them and tried again - same problem. No other visual problems are apparent. (Note: the user was a heavy smoker and I have had to clean the boards and chassis from top to bottom - the same problem existed before and after I cleaned everything.)
I did the usual steps of measuring voltages (all good) and unplugging boards in sequence and none of this made a difference. I then desoldered and checked cap C802 because of the sheer amount of reports that this goes bad, but it was absolutely fine.
Something changed around this point. Now when I plug it in, I don't get the LG logo anymore, just some momentary snow before there is no image (and no sound - there never has been), but the panel is 'on', instead of going into standby like before. The Y-SUS board is making some noise when powered, but not when the unit is off or in standby. Also, the red light on the main board is lit.
I have tried the AUTO_EXT_GEN test pattern feature and no picture is produced, though it does alter the sound coming from the Y-SUS board. There is a green light on the logic board, which is displaying what looks like an error code (one long dash, one short dash, repeated once) but I have no documentation to refer to (the service manual appears not to include such codes).
Any ideas?
p.s. I've noticed a common factor people discuss with this panel is clicking relays - mine appears to be a revision that has no relays.
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