LG 42LK450 Which Wire to Unplug Help

[mbosma]

I have an LG 42LK450 that we suspect was hit by a power surge during lightning storm.

The power light comes on and turns blue, but there is no faint picture or glowing at all.

Can someone take a look at these photos and help me troubleshoot what might be bad? From what I've read I need to remove some connections to figure out which boards are bad but don't know where to start or what they are called.

Thanks for any help you can provide.

-Matt

[newtothis]

Re: LG 42LK450 Which Wire to Unplug Help

Have a dmm?

[mbosma]

Re: LG 42LK450 Which Wire to Unplug Help

Yes, but not real experienced with it.

I know how to change the dials and take a reading but not sure what all of the different settings and numbers mean.

[newtothis]

Re: LG 42LK450 Which Wire to Unplug Help

Ok when your online hang about and I will help talk you through it

[newtothis]

Re: LG 42LK450 Which Wire to Unplug Help

From what I've read I need to remove some connections to figure out which boards are bad but don't know where to start or what they are called.

I am also assuming the posts you have read are about Plasma Displays.

What we will be doing is checking the power outputs from the Power Supply Unit (PSU) to see what is going on.

So you could you take a good clear picture of the cable that goes from the PSU to the main Board (the one with the HDMI inputs on it) on the PSU side so I can see the voltage labels next to it.

Cheers

[mbosma]

Re: LG 42LK450 Which Wire to Unplug Help

Ok. I'll do this when I get home today.

[newtothis]

Re: LG 42LK450 Which Wire to Unplug Help

Just post when your online and either me or someone else will help you through it

[budm]

Re: LG 42LK450 Which Wire to Unplug Help

This one looks like your power supply board. There are two fuses that need to be checked, one is for the main AC power, another one (next to the two black inverter transformers) is for the backlights inverter circuits.
http://www.shopjimmy.com/lg-eay62770...t-inverter.htm

[mbosma]

Re: LG 42LK450 Which Wire to Unplug Help

This image work? I'll look at the fuses too.

[newtothis]

Re: LG 42LK450 Which Wire to Unplug Help

Wrong connector.. I need to one ON the PSU that goes to the main

[newtothis]

Re: LG 42LK450 Which Wire to Unplug Help

The one highlighted yellow....

The blue mark I think indicated the Voltage Legend... i need to be able to see this.

And yes do check the 2 fuses as budm stated

[mbosma]

Re: LG 42LK450 Which Wire to Unplug Help



I also looked closely at the two fuses - visually they look fine to me. I'm available to work on it the next couple of hours. Txt# is 765-337-5714

[mbosma]

Re: LG 42LK450 Which Wire to Unplug Help

Tested both fuses. Dmm set on ohm 200 scale - readings for both we're 0.8. Don't know if this is good or bad, nor am I positive I did it correctly.

[Th3_uN1Qu3]

Re: LG 42LK450 Which Wire to Unplug Help

Fuses are good then.

[mbosma]

Re: LG 42LK450 Which Wire to Unplug Help

All, I did some more testing today. Plugged it in and tested for power at the connector pins on the cable. There was no voltage on any of the pins/wires. I then tested the fuse next to the plug and it had (130 v?) Then I tested the other fuse (both ends) by the two black inverters and there was no voltage there either. Does this mean the PSU board is bad?

[newtothis]

Re: LG 42LK450 Which Wire to Unplug Help

Ok the last pic you took for me on the PSU, You are saying there are no voltages there at all?

[mbosma]

Re: LG 42LK450 Which Wire to Unplug Help

Correct. DMM shows 0 on all of the pins.

[newtothis]

Re: LG 42LK450 Which Wire to Unplug Help

You can't be testing them right as you state you have a blue standby light, at least one of those pins will be giving off 5v.

Red probe to pin, black probe to the chassis (screw hole works well)

retest

[mbosma]

Re: LG 42LK450 Which Wire to Unplug Help

Going to go retest now. Back in 5.

[mbosma]

Re: LG 42LK450 Which Wire to Unplug Help

I still get no reading. I tried it with the pin plugged in testing the output and still nothing. I tried to change the multimeter to a different scale and still nothing. Should it be set to dcv on the 20 scale? With the black plugged into the COM hole?

Your absolutely right though- it's definatley my testing. The blue light will only turn on when the pin is connected.

Reminds me of how we troubleshoot computers... 95% of computer problems are located somewhere between the keyboard and the chair.