Lg 60pa6500 149v va

[bman4]

Got this plasma to fix and was told black screen.

The tv was working for me for a month after sitting unplugged for a year.

Then i was getting black screen with sound and button funtioning .

After i leave it unplugged it worked but now its worse.

No bad solder joints.

The logic board xd chip burns to the touch.

The logic board has a later date then the others and read about the reprogramming because out of sync .

I tried heating the logic board and dont know of it acclerated the turn off period.

The vsc id 29v when picture goes black and 150 when working.

When the screen is black and its on i get 5v , vs 204.9 va 55v .

When the tv is in test mode and working i get va is 149v.

With main disconnected the test mode still eventually goes blank screen.

The boards are all making noise as if they are working.

I think its logic or y board, might have to find a matching set.

If the va was 149 would it not fry the pannel.

Now with the tv black after working and no power button reset im getting no vsc , 149va , vs204.9, vy 249 and clicking noise from psu.

I heated the brown spots and heat sinks on sc or ymain and think i got a instnat black screen.

[bman4]

Re: Lg 60pa6500 149v va

Gonna rebuld this sc board because the igbts look like they been through hell, probably all degraded.

After heating the heat sinks on y main , sc board i think it got worse , it still works even with 149v va !

I cleaned all connections and the picture got cleaner and the power usage went down.

i had a long hot night of it working fine then it gave up the next day.

The logic is dated 2012 .10.19 and x and y is dated 2012.10.23.

Sincerely,
Bman4

[Biruslapio]

Re: Lg 60pa6500 149v va

What about the buffer boards? For 149V to be detected in VA, some voltage is leaking through the panel to the bottom adress buffers, very dangerous, could be these Renesas buffer chips shorting, but usually when they short the TV has an unstable image with lots of flickering, then it shuts down after some seconds.

https://www.badcaps.net/forum/showthread.php?t=88868

This user also had problems with the same TV, logic board dying, and VA voltage fluctuating.

[bman4]

Re: Lg 60pa6500 149v va

I will disconnect the buffers to see if the 149v is still there.

The picture is fine , No fluctuations in va voltage.

it looks like something was spilt on the y sus .

More testing for me.

Disconnected buffers and 149v is still present.

I think the y sus is leaking the 149v .

[Biruslapio]

Re: Lg 60pa6500 149v va

You should test the buffer IC pins forward voltages or resistance, not connecting them will cause the tv to produce no image of course, then it's not a proper diagnose.

[bman4]

Re: Lg 60pa6500 149v va

I was reading from vs to va pins thinking ground was black on this set.

From chassis ground i get steady 55v .


I think i have a intermitted open igbt or smd ect on y sus causeing vsc to drop .

[Biruslapio]

Re: Lg 60pa6500 149v va

Hm, I suspected something like that, but since you said VA was back to normal when screen was black, I thought it really was at 149V before.

So, do not heat up the Y-SUS more than it already does by itself, all these PA models suffer from Y-SUS and Y-buffers failures, and when the IGBTs blow it causes massive shorts across the board, Gate drivers, Optocouplers and SMD resistors all go bad.

It may just be bad soldering joints, but since you already ruled that out, change the energy saving options on the menu, if the TV does not shutdown on Medium, it's a problem with one of the sustain boards.

The XD logic board chip should not abnormally heat under any conditions, 60ºC is already considered burning hot for humans, how hot is it?

[bman4]

Re: Lg 60pa6500 149v va

Im really lucky ysus has not blown yet, alot of discoloration on the pcb.

I think its worse since i gave it a little heat.

I think the heat from resoldering everything sped up its failure.

Worked for a week with no issues after cleaning and resolder.

I checked the logic board with a temp gun and think it was above 60c and hurt to touch, will check again.

Someone posted that the y sus is married to logic and there was a reprogramming procedure in lg service manual and cant recall if that was just for a Pacific model.

Ive tried disabling eco features and low or high setting and think it made it worse.

Vsc drops, vy , va and vs 5v is still there and blink code changes on logic.

[Biruslapio]

Re: Lg 60pa6500 149v va

About the Y-SUS being linked to the logic board with something more than signals, not plausible, the only adjusts that board permits are -VY, VSC, and the er_up/dn signals, there's no eeprom or other trimpots on the board.

Is the Z-SUS fine? When it shuts down, is Z-BIAS (VZB) on spec?

[bman4]

Re: Lg 60pa6500 149v va

Well after re seating connections and removing the ysus and buffers it works again.

I dont know if its from flexing the board when removing ect.

I notice a heat pad had stains on it from something that was spilt and the back cover has evidence of a spill.

Cleaned the ysus and pads , it been working for 3h .

The logic board dose reach 60c exactly .

Thank you,
Happy holidays,
Bman4