LG 50PX4R-ZB stuck in standby mode

[surferbum]

Re: LG 50PX4R-ZB stuck in standby mode

If you reverse the probes on each board, what do you read? Is it any different?

ZSUS
BLACK PROBE ON CHASSIS & RED PROBE ON VS = 4.2 M ohms

RED PROBE ON CHASSIS & BLACK PROBE ON VS = 5.4 K ohms

YSUS
NOTHING CHANGES STILL 130 ohms

[tom66]

Re: LG 50PX4R-ZB stuck in standby mode

If you reverse the probes on each board, what do you read? Is it any different?

[surferbum]

Re: LG 50PX4R-ZB stuck in standby mode

Is GND-Vs measured like that on both Y-sus and Z-sus?

GND & Vs = 5.4 K ohms on ZSUS
GND & Vs = 0.120 K ohms on YSUS

[tom66]

Re: LG 50PX4R-ZB stuck in standby mode

Is GND-Vs measured like that on both Y-sus and Z-sus?

[surferbum]

Re: LG 50PX4R-ZB stuck in standby mode

OK GND-Vs continuity that low is bad. So you may have bad IPM or another fault on sus board.

Are there any checks i can do to try and determine the fault ??

Could it be YSUS or ZSUS or both ??

thanks

[tom66]

Re: LG 50PX4R-ZB stuck in standby mode

OK GND-Vs continuity that low is bad. So you may have bad IPM or another fault on sus board.

[surferbum]

Re: LG 50PX4R-ZB stuck in standby mode

Fuses SHOULD show continuity, your reading is not normal.

Hi tom

the fuses read 000.3 ohms

the continuity between gnd and vs reads 130 ohms with fuses in

[tom66]

Re: LG 50PX4R-ZB stuck in standby mode

Fuses SHOULD show continuity, your reading is not normal.

[surferbum]

Re: LG 50PX4R-ZB stuck in standby mode

Hi

I think i am miles away with finding out the cause of this fault ???

I just took the fuses out of the ysus board and GND and VS+ dont show continuity , so i am presuming it is normal.
I checked the continuity between GND and VS on the power board and they also have continuity so i presume these are normal ?
On the diagram TW attached it says to take out connectors P800, P802 and P803 on the power board.
P800 is on the main av board and there is nothing connected in P803 ???
Anyway i disconnected P800 and P802 and when powered up the TV does not turn on JUST the red light and thats it ????
Thanks for any help

[surferbum]

Re: LG 50PX4R-ZB stuck in standby mode

Hello Thanks for trying to help me out with my TV problem..... I have done some continuity testing on the power board and ysus and zsus.( not switched on !)
I might be totally wrong BUT i am thinking it is the YSUS board ???? The reason i say this is because i have continuity between grounds and all the vs+ on the YSUS board with the power leads and zsus lead disconnected.
Have i got a short somewhere between ground and VS+ and where do you think the fault could lie ????
Thanks steve

Forgot to mention the resistance between ground and VS+ is 130 ohms

[surferbum]

Re: LG 50PX4R-ZB stuck in standby mode

Tom, this set appears to use the same ysus,zsus as the 50PX5D. I'd have a closer look for shorts, blown fuses or symptoms on those boards and IPMs.

The initial post symptoms sounds like it could be protection mode. I don't remember all the ins and outs of the couple I had but sounds similar and I know on those you'd get a click , LED would change then back to standby in about 10secs.

IPMs replaced on both Y & Z got that junker going again and a bad Ysus was burning up resistors on the Z.
Horrible TVs to work on, the LG Fallas TV trainig guide would be close to this, but the translation to english makes the flow charts near impossible to understand.

There's a note , Unable to check voltage when disconnecting Ysus due to 50" protection?

Hello Thanks for trying to help me out with my TV problem..... I have done some continuity testing on the power board and ysus and zsus.( not switched on !)
I might be totally wrong BUT i am thinking it is the YSUS board ???? The reason i say this is because i have continuity between grounds and all the vs+ on the YSUS board with the power leads and zsus lead disconnected.
Have i got a short somewhere between ground and VS+ and where do you think the fault could lie ????
Thanks steve

[surferbum]

Re: LG 50PX4R-ZB stuck in standby mode

Hi again !!

I cannot send the main board back so i am going to try and sell it on ebay !! I was then going to buy a power supply board for it ?

Thanks Tw for the protection mode diagram. I will test it out tommorow after work.

The TV defenitely makes a click sound when first turned on just before it goes back to standby, however if i turn it on again by the remote it does NOT click. It only clicks when i unplug the tv and plug back in ??

Thanks again for your help

[tw2005]

Re: LG 50PX4R-ZB stuck in standby mode

Tom, this set appears to use the same ysus,zsus as the 50PX5D. I'd have a closer look for shorts, blown fuses or symptoms on those boards and IPMs.

The initial post symptoms sounds like it could be protection mode. I don't remember all the ins and outs of the couple I had but sounds similar and I know on those you'd get a click , LED would change then back to standby in about 10secs.

IPMs replaced on both Y & Z got that junker going again and a bad Ysus was burning up resistors on the Z.
Horrible TVs to work on, the LG Fallas TV trainig guide would be close to this, but the translation to english makes the flow charts near impossible to understand.

There's a note , Unable to check voltage when disconnecting Ysus due to 50" protection?

[tom66]

Re: LG 50PX4R-ZB stuck in standby mode

Can you return your main board?

[surferbum]

Re: LG 50PX4R-ZB stuck in standby mode

OK so i need to replace the power supply board ?

I will have to try and find one !!

Thanks again

[tom66]

Re: LG 50PX4R-ZB stuck in standby mode

I would not expect so. With bad caps you'll typically get an output voltage but it will be lower or higher than it should be.

[surferbum]

Re: LG 50PX4R-ZB stuck in standby mode

OK thanks for your help tom .... do you think it could be a capacitor problem ... ive heard that sometimes a bad cap might still visibly look ok ?? ive bought a new impedence meter but only goes to 2000uF

[tom66]

Re: LG 50PX4R-ZB stuck in standby mode

I am not certain, but I would try that next. Unfortunately it is difficult to be certain.

[surferbum]

Re: LG 50PX4R-ZB stuck in standby mode

do you think that this indicates a faulty power supply thanks

[surferbum]

Re: LG 50PX4R-ZB stuck in standby mode

The power supply produces the voltages, which come up at those outputs.
Do you hear a relay click when you press the power button?

Yes .... when the tv is first powered up then by pressing the power button on the remote.

If i try pressing the button on the remote again it does not click ONLY when unplugged and plugged back in ??