Having benefitted greatly from Tom666's excellent detective work on the LG AC detect problem, I was able to do a fix for this model using that technique, so I thought I'd try and supply some details for anyone else. Full credit to Tom666 really.
I had the set for a few years (manufactured 2007) before getting plagued with random power offs. Doing some research, most of the hits were related directly to the classic bad caps on powerboard diagnosis.
I found a kit that was recommended for that, but having swapped the caps, had the same problem, hence more research leading to Tom666's explanation.
First off - identifying the problem. After the power offs happen, you can see the power off history via the on screen diagnostic menu. To access that, press and hold the menu button on the side of the set, and then press and hold the menu button on the remote control as well. From the resulting menu, you can see the power off history as shown in "power off small.jpg". Entries that show "5V Monitor" are "AC detect" issues - i.e. false detections of a fault on the incoming mains supply. To verify that, you can just pull the power at the mains socket, and then check the menu again. You should see another "5V Monitor" entry, based on a real detection of mains failure (as opposed to the false detections that cause random shutdowns).
Next up - fixing the problem. Disassembling the set was pretty straigforward (sorry, I didn't do any pics of that) - basically just screws around the sides on the back of the case. Power board is shown in the full-power-board.jpg . Power board model number is EAY38640201 - possibly also EAY39702801 - I guess those are variants. For the classic bad caps, those are ones mostly in the bottom right hand corner of that pic (although they weren't relevant for me).
There are four couplers that bridge the Primary/Secondary divide. A single one (shown in "1 coupler.jpg") doesn't matter for this fix. Then there is a bank of three (shown in "3 couplers.jpg"). Of those three, PC130 is the only one the bridges in the "correct" direction for the fix. To make the fix, the pins on the right hand side of this photo are the ones that need shorting - i.e. the ones nearest the edge of the board.
After that, hours of trouble free viewing
Hope that's useful for someone else.
Simon
I had the set for a few years (manufactured 2007) before getting plagued with random power offs. Doing some research, most of the hits were related directly to the classic bad caps on powerboard diagnosis.
I found a kit that was recommended for that, but having swapped the caps, had the same problem, hence more research leading to Tom666's explanation.
First off - identifying the problem. After the power offs happen, you can see the power off history via the on screen diagnostic menu. To access that, press and hold the menu button on the side of the set, and then press and hold the menu button on the remote control as well. From the resulting menu, you can see the power off history as shown in "power off small.jpg". Entries that show "5V Monitor" are "AC detect" issues - i.e. false detections of a fault on the incoming mains supply. To verify that, you can just pull the power at the mains socket, and then check the menu again. You should see another "5V Monitor" entry, based on a real detection of mains failure (as opposed to the false detections that cause random shutdowns).
Next up - fixing the problem. Disassembling the set was pretty straigforward (sorry, I didn't do any pics of that) - basically just screws around the sides on the back of the case. Power board is shown in the full-power-board.jpg . Power board model number is EAY38640201 - possibly also EAY39702801 - I guess those are variants. For the classic bad caps, those are ones mostly in the bottom right hand corner of that pic (although they weren't relevant for me).
There are four couplers that bridge the Primary/Secondary divide. A single one (shown in "1 coupler.jpg") doesn't matter for this fix. Then there is a bank of three (shown in "3 couplers.jpg"). Of those three, PC130 is the only one the bridges in the "correct" direction for the fix. To make the fix, the pins on the right hand side of this photo are the ones that need shorting - i.e. the ones nearest the edge of the board.
After that, hours of trouble free viewing
Hope that's useful for someone else.
Simon
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