LG 42LD420 no power

[rtstorm]

Re: LG 42LD420 no power

Oke i try that, all are 0V except 3.3V

[nomoresonys]

Re: LG 42LD420 no power

ok, now it's tricky but you can use a little precision flat blade screwdriver to lift the little tab that holds the wire in place and slip it out of the connector, you want to remove inverter on-off wire from connector on powerboard side, done with tv unplugged from power.

[rtstorm]

Re: LG 42LD420 no power

Ok, i remove it and test. Still 0V on Stand-by and 0V when Power On

[nomoresonys]

Re: LG 42LD420 no power

then temporarily just tape the metal end of wire you removed so it doesn't accidentally contact anything, then with that wire out of the way, put the connector back in place, make sure that wire is out of the way and taped off, use about a 1k resistor to jumper from 3.5 to inverter on-off, then test tv.

[rtstorm]

Re: LG 42LD420 no power

Yea, now the backlight is working but no picture

[nomoresonys]

Re: LG 42LD420 no power

ok, that should mean that your backlights and powerboard are ok, looks like the damage is on the mainboard, maybe test some things there, maybe check the voltage regulators on the mainboard, some testing there: https://www.youtube.com/watch?v=ocqnqmBxiqY

[rtstorm]

Re: LG 42LD420 no power

Thank you, will continue tomorrow.

[nomoresonys]

Re: LG 42LD420 no power

can also check the fuse on tcon board, see if its blown, see if you have any voltage on either end of fuse neg. probe on chassis.

[rtstorm]

Re: LG 42LD420 no power

I check it and no voltage is goint to tcom board. So i guess the MB is dead. I check under microscope whole board and no shorts or visible damage. I found this component and i do not know what is it?
Label A952 (X1002 on board)

[nomoresonys]

Re: LG 42LD420 no power

well it's not totally dead, it's sending some signals but not inv on-off to the powerboard but it could be partially dead, ever since I fixed my sony that was took out by lightning with a firmware update, I never rule out that a firmware update might do the trick but I don't know, the lightning may have just killed part of the board, but if all that is too hard to do, then a replacement mainboard should bring it back to life and may be the simplest solution.

[diif]

Re: LG 42LD420 no power

Give the processor some heat, it's an LD series, so there's a good chance its suffering from BGA failure.

[rtstorm]

Re: LG 42LD420 no power

well it's not totally dead, it's sending some signals but not inv on-off to the powerboard but it could be partially dead, ever since I fixed my sony that was took out by lightning with a firmware update, I never rule out that a firmware update might do the trick but I don't know, the lightning may have just killed part of the board, but if all that is too hard to do, then a replacement mainboard should bring it back to life and may be the simplest solution.

I would try to reflash it but i do not think that there are a fw update online or bios .bin file to flash

[nomoresonys]

Re: LG 42LD420 no power

Indeed, that's always a problem, the tv makers just can't wait to take the firmware off their sites or just never make it available in some cases, they would rather sell us another tv than give us a way to fix the one we already laid out good money for.

[rtstorm]

Re: LG 42LD420 no power

Hey i found a board on ebay but the seller say that the board is from model: 37LD420
The board have the same code on it (attachment). Only EBU number is different but EAX number is the same. Will this work on my 42LD420?

[rtstorm]

Re: LG 42LD420 no power

Hello, just a quick update on this. I replace the main board and TV works. Thank you

[nomoresonys]

Re: LG 42LD420 no power

glad to hear it, was it the board in post #34 that worked for you?

[rtstorm]

Re: LG 42LD420 no power

No, it was this one from ebay