YP1922-4L LCD power board repair

[Honziq]

I have LG LCD TV. When I turn on the TV backlight turns on for 1 sec and then goes back off. I think it is bad invertor. But i dont know, which of components is bat. MOSFETs and caps seems OK.
Help me, please.
Thanks.

[selldoor]

Re: YP1922-4L LCD power board repair

Ok you need to test the inverter transformers secondary windings.
No Power to Board
Meter on Ohms 2000 test S1 to S2 and S3 to S4 and post the results
I will be going to bed soon - early start tomorrow - someone else might follow up

Which country are you in and mains voltage

[Honziq]

Re: YP1922-4L LCD power board repair

Ok you need to test the inverter transformers secondary windings.
No Power to Board
Meter on Ohms 2000 test S1 to S2 and S3 to S4 and post the results
I will be going to bed soon - early start tomorrow - someone else might follow up

Which country are you in and mains voltage

S1 to S2 - 1080 Ohm
S2 to S3 - 1092 Ohm

[Honziq]

Re: YP1922-4L LCD power board repair

Ok you need to test the inverter transformers secondary windings.
No Power to Board
Meter on Ohms 2000 test S1 to S2 and S3 to S4 and post the results
I will be going to bed soon - early start tomorrow - someone else might follow up

Which country are you in and mains voltage

Hello,
I am in Czech Republic, mains voltage is 220V.

[selldoor]

Re: YP1922-4L LCD power board repair

Ok they look alright. Are the leads on the lamps long enough for you swap each pair over.
Often the bulbas at the top age faster and developa a higher resistance.
Do you have any spare bulbs /another faulty ,even broken monitor or laptop screen.

[Honziq]

Re: YP1922-4L LCD power board repair

Thanks,
i try to swap tubes with one laptop screen tube.
One of the top tubes is bad. When laptop screen is connected TV running always.
Thanks a lot.

[selldoor]

Re: YP1922-4L LCD power board repair

Good - Hopefully you can get a tube for it - if its just for yourself and is watchable with just 3 lamps I have heard of people just sitting a bulb inside the back to make it work but to save having to attack the panel. Bulb fitting can be quite tricky.

[Lumberjack777]

Re: YP1922-4L LCD power board repair

Good - Hopefully you can get a tube for it - if its just for yourself and is watchable with just 3 lamps I have heard of people just sitting a bulb inside the back to make it work but to save having to attack the panel. Bulb fitting can be quite tricky.

Nice job diagnosing that problem so quickly selldoor.

I'm one of those people that simply tapes a bulb about the same size or smaller to the panel. And cover it with black electrical tape or duct tape. Unless its a valuable monitor, its way too much trouble to disassemble and spend $15 or more for a bulb for a $25 monitor. We might start replacing with LED strips someday soon.