LG 42" Plasma 42PJ560R - no picture

[tom66]

Re: LG 42" Plasma 42PJ560R - no picture

Well, this is difficult, do you have any access to an oscilloscope?

[abhi1981]

Re: LG 42" Plasma 42PJ560R - no picture

No, I don't have an oscilloscope.

One more thing, the green LED doesn't glow on the control board.

[tom66]

Re: LG 42" Plasma 42PJ560R - no picture

Not at all, no flashing etc.?

[abhi1981]

Re: LG 42" Plasma 42PJ560R - no picture

No, nothing at all. It used to blink when the set was working. Now, it doesn't glow at all.

[tom66]

Re: LG 42" Plasma 42PJ560R - no picture

Hmm. Johnboy on this forum had a problem with the control board on the American version of this TV. Possibly the same issue?

[abhi1981]

Re: LG 42" Plasma 42PJ560R - no picture

How can I check the control board ?

[tom66]

Re: LG 42" Plasma 42PJ560R - no picture

The jumper before should have worked if the control board was OK, but that may also be caused by bad sustain boards. However, I think the LED would still blink if there was an error, it just may only blink a few times.

[abhi1981]

Re: LG 42" Plasma 42PJ560R - no picture

So, should I check the YSUS board? Could a bad YSUS board cause the LED to stop blinking?

[tom66]

Re: LG 42" Plasma 42PJ560R - no picture

The LED should blink at least once, if not several times, before shutting down. Assuming that the YSUS and ZSUS are isolated while you check LED, which I think you did previously?

[abhi1981]

Re: LG 42" Plasma 42PJ560R - no picture

I will check it again. How to isolate the YSUS and ZSUS boards?

[tom66]

Re: LG 42" Plasma 42PJ560R - no picture

Just disconnect the power from the power supply.

[abhi1981]

Re: LG 42" Plasma 42PJ560R - no picture

I did like you said. The LED did not blink even once and a sort of sparking electrical noise (like when you are tuning a radio) was coming from the power supply board. It disappeared when I restarted the set after reconnecting the power to the YSUS.

[tom66]

Re: LG 42" Plasma 42PJ560R - no picture

Vs=203v
va=59v

^Previously you made those measurements... was that with the Y-SUS and Z-SUS connected?

[abhi1981]

Re: LG 42" Plasma 42PJ560R - no picture

Yes.

[tom66]

Re: LG 42" Plasma 42PJ560R - no picture

I would suspect the control board is bad.

[abhi1981]

Re: LG 42" Plasma 42PJ560R - no picture

How can I test the control board?

[tom66]

Re: LG 42" Plasma 42PJ560R - no picture

You can't, easily. There are some voltage regulators on it,
https://www.badcaps.net/forum/showthread.php?t=22231
but that's it.

[abhi1981]

Re: LG 42" Plasma 42PJ560R - no picture

Can it be possible that there are bad capacitors on the YSUS board that is causing the display to go black- a common problem with LG TVs. As I earlier said that the TV used to start with a black screen and started working in a single on/off try and the number of tries increased with time . Maybe the logic board is not giving any test pattern because of this.

[tom66]

Re: LG 42" Plasma 42PJ560R - no picture

As I said, that is unlikely, because from what I know about LG control boards is they will attempt a few cycles, blinking the LED, before giving up due to fault detection.

[abhi1981]

Re: LG 42" Plasma 42PJ560R - no picture

By blinking LED do you mean the red power led or the green control board led. The red power led never blinks , it lights up and fades out as the set powers on-- just like normal operation.