LG 42LB5610 no reaction at all after lightning

[wylcot]

A friend's parents gave me that 4k TV set after lightning struck our village, saying "if you can fix it...". Their insurance had paid for a new one.

It just doesn't do anything when plugged, or pushed on the I/O button.

So I thought I'd buy a new power board, but actually, it didn't change anything.

Do you guys think the motherboard could be faulty?
If so, where could i check tensions, please?

[neilc6]

Re: LG 42LB5610 no reaction at all after lightning

Basic troubleshooting for dead TVs.
1. Check main fuse. If blown, you likely have shorted components (FETs or diodes) on the power supply.
2. Measure for standby voltage. The main board needs voltage to be in standby mode and to accept the commands to turn on the TV. If no standby voltage, the power supply is suspect. Maybe marked 5VSTB, VSB, 5V...
3. Check for PS-ON and BL-ON signals from the main board. These two signals are used to turn on the power supply (additional voltages) and turn on the backlight. If the main board has power and it isn't sending these signals, the main board is suspect.

[wylcot]

Re: LG 42LB5610 no reaction at all after lightning

Thanks Neil,

So I've checked the 2 fuses on the power supply, and they're ok.

I guess I'd need the manual to know where to check the standby voltage...?

[dick_barton]

Re: LG 42LB5610 no reaction at all after lightning

If this is your board then the voltages to check are given

[wylcot]

Re: LG 42LB5610 no reaction at all after lightning

Oh well, that's absolutely true !

So I don't seem to get much, except 3.5v approximately where it's supposed to be...

I'm guessing the 12 and 24 show up when it decides to turn on...?

[dick_barton]

Re: LG 42LB5610 no reaction at all after lightning

You can do the same test as in your JVC thread to test the power supply. For this supply connect Standby to PWR_ON and Standby to DRV_On using 1K resistors
https://www.badcaps.net/forum/showthread.php?t=91406

[wylcot]

Re: LG 42LB5610 no reaction at all after lightning

Cool !
Do you mean I need two resistors and connect them at the same time?
And then it should have the other tensions reappear, correct ?

[dick_barton]

Re: LG 42LB5610 no reaction at all after lightning

Yes, the use of two resistors is correct.

[wylcot]

Re: LG 42LB5610 no reaction at all after lightning

Different situation here (compared to my other tv)

I connected Standby to PWR_ON and Standby to DRV_On, and I did have the backlight on.

So the mainboard is faulty, right ?

[dick_barton]

Re: LG 42LB5610 no reaction at all after lightning

If all the secondary supplies come up as well as the backlights then the power supply is working correctly.

[wylcot]

Re: LG 42LB5610 no reaction at all after lightning

I'll check that tomorrow.
And if that's the case, you suggest to get a used main board ?