LG 60PM6700 no picture no sound

[CriticalCritic]

Re: LG 60PM6700 no picture no sound

Thanks for the advice. I have replaced the entire power supply board already though, no change. To be clear, one of the black metal heat sinks on the ysus board is getting very hot. After 20 min of good picture and sound, the TV turns itself off.
I have also replaced the ysus board (first), and also the upper and lower y buffer boards (second). No change in the symptom.
Starting to wonder if the old y buffer boards blew out my new ysus board.

Any advice greatly appreciated ... Bill H.

Hi Bill!
I'm having the exact same problem with the exact same TV! Did you figure out how to fix this problem?

[Unspun01]

Re: LG 60PM6700 no picture no sound

tnbugman and CriticalCritic:

On each of the YSUS and ZSUS boards, please check the quality of the solder connections on the underside of the boards under the pair of large copper coils. There is possibility that these solder connections are burned or poor. Reflow the connections with flux and new leaded solder.

Are the solder connections ok, or do they look cracked/burned/discolored? Report back with your observations.

[pkwhite]

Re: LG 60PM6700 no picture no sound

Go to the logic control board in the middle of the set. Flip up the brown latch on P231 and remove the flat ribbon. Put a paper clip in the 2 holes marked EXT_AUTO_GEN. Power on the tv and check if the test screens come on. If they do, the mainboard is bad.

This was a great hint. I have good test patterns using this test technique. I have swapped the main board with new assemblies...twice. No picture or sound with the original or either of the two *new* replacement main boards. Searching for another clue for where to look for the issue(s). Sure seems like it is external to the main board but somehow related. Perhaps somebody has come across another defect which would kill the picture and sound but not be on the main board? This is a 65PB6900.

[diif]

Re: LG 60PM6700 no picture no sound

This was a great hint. I have good test patterns using this test technique. I have swapped the main board with new assemblies...twice. No picture or sound with the original or either of the two *new* replacement main boards. Searching for another clue for where to look for the issue(s). Sure seems like it is external to the main board but somehow related. Perhaps somebody has come across another defect which would kill the picture and sound but not be on the main board? This is a 65PB6900.

The test shows the whole of the TV is working apart from the mainboard and cable you have disconnected. You say you've put two new boards in, were they brand new ? Check both ends of the cable, perhaps it has picked up a little damage.

[Unspun01]

Re: LG 60PM6700 no picture no sound

If you get test patterns (after disconnecting the mainboard from the logic board, and placing the jumper on the logic board), then the logic board, YSUS, ZSUS, power supply boards are in working condition. Also, the cables connecting these boards to each other, or to the screen are likely good too.

This test isolates the problem to the main board since all others are working. The only other issue could be a damaged or pinched cable between the mainboard and logic board.

Are you certain that your two replacement boards are actually for your TV? There could be many mainboards with same board number and same components, but possibly have different firmware from different models?

Can you confirm 65PB6900? I cannot locate any information on this model number anywhere?

How or where did you buy the replacement boards? are you certain they are exact model numbers?

[pkwhite]

Re: LG 60PM6700 no picture no sound

If you get test patterns (after disconnecting the mainboard from the logic board, and placing the jumper on the logic board), then the logic board, YSUS, ZSUS, power supply boards are in working condition. Also, the cables connecting these boards to each other, or to the screen are likely good too.

This test isolates the problem to the main board since all others are working. The only other issue could be a damaged or pinched cable between the mainboard and logic board.

Are you certain that your two replacement boards are actually for your TV? There could be many mainboards with same board number and same components, but possibly have different firmware from different models?

Can you confirm 65PB6900? I cannot locate any information on this model number anywhere?

How or where did you buy the replacement boards? are you certain they are exact model numbers?

Thanks for fast replies! The Model was incorrect....it is a 60PB6900-UA. The replacement main boards have identical screen printed identifiers across the top starting with PU42A and the part number is EAX65399305. The first new replacement came from abcaGroup and they claimed it was new and offered to send another if I returned the first...which was done. Neither new board brought back picture or sound. I am double checking cables. Voltages coming in from the top of the circuit assembly match the labeling, but I will double check. I have not confirmed firmware differences. The symptoms have been consistent from what I first experienced with the original board. So, I haven't turned over the right rock yet! Thanks again for your help!

[pkwhite]

Re: LG 60PM6700 no picture no sound

My pals diff and Unspun01 nudged me to recheck cables. So, after carefully reseating the flex cable, the set appears to be functioning. Thanks again for your replies!

[Unspun01]

Re: LG 60PM6700 no picture no sound

My pals diff and Unspun01 nudged me to recheck cables. So, after carefully reseating the flex cable, the set appears to be functioning. Thanks again for your replies!

Right on! Glad to hear you got it working. Hang onto those other boards in case you ever need them...

[tvtimmy]

Re: LG 60PM6700 no picture no sound

Good job guys!