LG TV 42LW5700 does not power on fully (PSU EAX62865401/Main board EAX64405501)

[atari1968]

My LG 42LW5700 doesn't power on. when tv plugged on the standby light is
a very week until I switch power on then the standby light blinking slowly.

After checking the power supply,
I measured the output voltage after switch on and everything looks okay

Please see the attached picture of the voltage test for the output ports.

So probably the power supply is ok and the problem could be on the mainboard EAX64405501,
The standby led is always very dim until I switch on and then the led start to blink (high and dim not in the same rate).

What do you think from the measure? What do I need to check next?

I cannot find the boards schematic on the web.

please see the pictures below.

Any help will be appreciated.
Thanks!

[budm]

Re: LG TV 42LW5700 does not power on fully (PSU EAX62865401/Main board EAX64405501)

The chart is useless without having the pin name for each pin.

[tvtimmy]

Re: LG TV 42LW5700 does not power on fully (PSU EAX62865401/Main board EAX64405501)

I believe the mainboard is bad. You can remove the black heatsink and thermal pad and hit the cpu with a heat gun for 45 seconds. If it turns back on, there's the problem. It may last anywhere from a week to 5 years.....nobody knows for sure.

[nomoresonys]

Re: LG TV 42LW5700 does not power on fully (PSU EAX62865401/Main board EAX64405501)

With tv unplugged, unhook cable from powerboard to mainboard, plug tv back into power, see if backlights come on.

[atari1968]

Re: LG TV 42LW5700 does not power on fully (PSU EAX62865401/Main board EAX64405501)

The chart is useless without having the pin name for each pin.

I added the test on the board in a yellow background.
Thanks for your comment.

[atari1968]

Re: LG TV 42LW5700 does not power on fully (PSU EAX62865401/Main board EAX64405501)

With tv unplugged, unhook cable from powerboard to mainboard, plug tv back into power, see if backlights come on.

Thanks for your advice, already done this, but unfortunately, that's not the case.

[atari1968]

Re: LG TV 42LW5700 does not power on fully (PSU EAX62865401/Main board EAX64405501)

I believe the mainboard is bad. You can remove the black heatsink and thermal pad and hit the cpu with a heat gun for 45 seconds. If it turns back on, there's the problem. It may last anywhere from a week to 5 years.....nobody knows for sure.

Thanks, but I want to figure out the exact point first.

[nomoresonys]

Re: LG TV 42LW5700 does not power on fully (PSU EAX62865401/Main board EAX64405501)

That pdf is just a no help picture, the picture in the first post is the way to do it. DON'T need anything fancy, just put down what it says on the label for connector P201, type it out. Test connector from mainboard to powerboard on powerboard side with all boards hooked up, test with tv plugged in but off then hit power, report both conditions here, give pin number, pin description/name and condition both off and when you hit power on. So we can see all the voltages and what they are doing. Try to do test just as instructed, example in second link below if needed. Try to do it just as instructed, if you don't understand something just ask, someone here will probably know.

[atari1968]

Re: LG TV 42LW5700 does not power on fully (PSU EAX62865401/Main board EAX64405501)

With all boards hooked up,
The measurements data is in two conditions:
Plugged in tv off
Plugged in tv on

[nomoresonys]

Re: LG TV 42LW5700 does not power on fully (PSU EAX62865401/Main board EAX64405501)

Looks like the mainboard isn't sending the DRV-ON signal.

[nomoresonys]

Re: LG TV 42LW5700 does not power on fully (PSU EAX62865401/Main board EAX64405501)

I would try to verify the backlights and powerboard, don't know if this powerboard has pullup resistors, may have to use resistors to jumpstart the powerboard by itself, YOU MUST HAVE MAINBOARD UNPLUGGED FROM POWERBOARD IF YOU DO THIS TEST, usually done by connecting the standby pin to power on and drv-on may also need a resistor going to pwm on, so you would use 2 or 3 resistors, then if backlights come on, it's most likely the mainboard at fault.

[EonFlask]

Re: LG TV 42LW5700 does not power on fully (PSU EAX62865401/Main board EAX64405501)

Hi,

I hope that this will you with your problem.

Regards,

[1015286969]

Re: LG TV 42LW5700 does not power on fully (PSU EAX62865401/Main board EAX64405501)

Hi, I realized this is an old thread but just wanted to share my experience. Mine is a LG 47LW5700 and had the same voltage readings as the original author. I baked the main board at 300F for 18min, and worked like a charm. Hope this helps if anyone is looking for advice =)

[neilc6]

Re: LG TV 42LW5700 does not power on fully (PSU EAX62865401/Main board EAX64405501)

LE, LV, LW, LS series all have BGA issues. Lots of repair services on ebay. Home baking is a temporary fix and your problem will likely come back.