LG 37LD450 Doesn't Turn On

[Paul678]

The red standby LED turns on solid when I plug the unit
in, but when I hit the power button, the LED slowly
gets dimmer, and then slowly gets brighter, and then
repeats this undulation.

I cannot turn the undulation off with the power button: I
must unplug the unit and plug it back in, to get the solid
red LED again. Nothing shows up on the screen at any
time.

All voltages on the power supply seem normal: 3.5V, 12V,
and 20V. But I don't know of a way to check if the high
voltage going to the CCFLs is turning on or not.

I was thinking this is likely a main motherboard issue, but
it seems possible the high voltage going to the CCFLs
is the problem.

What do you all think?

[Hamie]

Re: LG 37LD450 Doesn't Turn On

Jumping the backlights on would answer your questions.

Uploading pictures of the boards would help.

[ReeceyBurger123]

Re: LG 37LD450 Doesn't Turn On

Bga issue on mainboard.

[dskall]

Re: LG 37LD450 Doesn't Turn On

Pson, blon voltages, image on screen with flashlight, flash on screen from backlights, pictures?

[Paul678]

Re: LG 37LD450 Doesn't Turn On

Pson, blon voltages, image on screen with flashlight, flash on screen from backlights, pictures?

After pressing the power button:

Power-On=3.2V
INV On/Off= 0 V

I could not see an image on the screen while using a strong flashlight
on it.

I also noticed a scratch about 1/2 inch right in the middle of the screen....so maybe this one isn't a good candidate to revive anyways!

[dskall]

Re: LG 37LD450 Doesn't Turn On

I would say mainboard, maybe eeprom

[Paul678]

Re: LG 37LD450 Doesn't Turn On

Here are some pics:

https://www.flickr.com/photos/132723...h/33141927281/

[Hamie]

Re: LG 37LD450 Doesn't Turn On

As reecy pointed out already.
Looks like the set uses an XD engine bga. Prone to cracking. Try reflowing it.

[Paul678]

Re: LG 37LD450 Doesn't Turn On

As reecy pointed out already.
Looks like the set uses an XD engine bga. Prone to cracking. Try reflowing it.

I haven't tried that in years.....link to help refresh my memory
of how to do that again?

[dskall]

Re: LG 37LD450 Doesn't Turn On

Lots of youtube videos.

[Paul678]

Re: LG 37LD450 Doesn't Turn On

Lots of youtube videos.

Ok, here's one:

http://hackaday.com/2011/02/24/heat-...-fixes-laptop/

Should i remove the heatsink first?

[diif]

Re: LG 37LD450 Doesn't Turn On

Should i remove the heatsink first?

Yes. I find it easier to remove them by twisting, rather than pulling straight up.

[ReeceyBurger123]

Re: LG 37LD450 Doesn't Turn On

Remove heatsink, reflow if it works, give it a good reflow and then reapply heatsink with thermal silicon and maybe even add a fan. This is one of these shite Lgs that the cpu heatsink covers half the bloody chip !!!

[diif]

Re: LG 37LD450 Doesn't Turn On

Your hackaday link doesn't detail it, but add some flux around the chip before you reflow.