Vizio P42HDTV10A with LG internals shutting off after 15 seconds.

[johnboy1313]

I picked this set up yesterday because I have a ton of parts for these LG plasmas lying around. It showed the symptoms of a bad YSUS board. I brought it home, swapped in a good YSUS and buffer and turned it on. It showed a good screen with the typical sparklies, but then it shut itself off. One at a time, I unplugged the YSUS and the ZSUS with no improvement. After 15 seconds, it shuts off. I swapped in a different PSU, it still shuts off. At this point, I figured it was either the Sub-PSU, which I don't have an extra of, or something on the main board, which I also don't have an extra of. The sub-PSU showed correct voltages, even after the unit shuts off so I focused my attention to the main. I've traced it even deeper to either the tuner board (the small square board on the left in the pic showing the whole main) or the circuit on the main that powers the tuner board. With the tuner unplugged, the unit will power on and stay on but none of the controls work i.e power, menu, channel, etc. From the unplugged connector, left to right, I see...

12V
12V
0.0V
0.0V
5V

This makes me believe the main is functioning, but there is a short on the tuner somewhere. I've verified all surface mount voltage regulators are outputting the correct voltages per their label. There are two more larger regulators that show as follows...

U1
7805CT
RRD605 G
12V
0V
5V

U2
MSP1250
ADJS
52N03
5V
3.3V
0V
1.2V
0V

At this point, I'm leaning towards a bad tuner board, but I guess there is a possibility that the main board could have a problem when that circuit is under load.

Any thoughts?

[johnboy1313]

Re: Vizio P42HDTV10A with LG internals shutting off after 15 seconds.

With just the 5V wire pulled from the plug to the tuner board, the tv will power up with no controls.

[selldoor]

Re: Vizio P42HDTV10A with LG internals shutting off after 15 seconds.

checked the fuse on the tuner board?

[johnboy1313]

Re: Vizio P42HDTV10A with LG internals shutting off after 15 seconds.

Yeah, I checked both fuses on the main board too. They all check good.

[tom66]

Re: Vizio P42HDTV10A with LG internals shutting off after 15 seconds.

Check the control board for an AUTO GEN option.

[johnboy1313]

Re: Vizio P42HDTV10A with LG internals shutting off after 15 seconds.

The control board is the main board right?

[tom66]

Re: Vizio P42HDTV10A with LG internals shutting off after 15 seconds.

No, it is the equivalent of a T-con on this LG plasma.

[johnboy1313]

Re: Vizio P42HDTV10A with LG internals shutting off after 15 seconds.

OK, I found it. It's a connector with four pins.

[johnboy1313]

Re: Vizio P42HDTV10A with LG internals shutting off after 15 seconds.

What should I do with it?

[tom66]

Re: Vizio P42HDTV10A with LG internals shutting off after 15 seconds.

Can I see a picture of it?

[johnboy1313]

Re: Vizio P42HDTV10A with LG internals shutting off after 15 seconds.

Here you go.

[tom66]

Re: Vizio P42HDTV10A with LG internals shutting off after 15 seconds.

Wire up the PSON and VSON so you get good Vs/Va.
Short pins 1-2 of the AUTO GEN.
Do test patterns appear?

[johnboy1313]

Re: Vizio P42HDTV10A with LG internals shutting off after 15 seconds.

It would appear that the panel works fine. I can connect a signal to the set and see a good picture. The only problem is that the power supply shuts off after 15 seconds when the tuner board is connected.

Do you think it's a bad panel causing the set to power off?

[tom66]

Re: Vizio P42HDTV10A with LG internals shutting off after 15 seconds.

I doubt it, a panel cannot fail in such a way. If the picture is good (minimal to no maldischarge, no stuck rows/columns) then there should be no issue.
Perhaps the tuner board has an erroneous sleep timer set up?

[johnboy1313]

Re: Vizio P42HDTV10A with LG internals shutting off after 15 seconds.

I ordered a tuner board. I'll update when it's installed.

[johnboy1313]

Re: Vizio P42HDTV10A with LG internals shutting off after 15 seconds.

New tuner board installed, TV still shuts off. I've got one more ace up my sleeve. If that doesn't work, I'm going to strip it down and swap the panel into a 42" Akai that I've got in the basement. It uses the same PSU, Y-SUS, Z-SUS, buffers, and logic board, but a different main and no sub-PSU.

[johnboy1313]

Re: Vizio P42HDTV10A with LG internals shutting off after 15 seconds.

No dice. Something is up with the 5V circuit in the main board. I'm going to swap this panel into the other set when I have time and (hopefully) be done with it.

[tom66]

Re: Vizio P42HDTV10A with LG internals shutting off after 15 seconds.

I emplore you to avoid these LG based plasmas in future (42X2, 42X3, 42X4, 50X3, 50X4 etc.) They are utter nightmares.

[johnboy1313]

Re: Vizio P42HDTV10A with LG internals shutting off after 15 seconds.

Yeah, I'm done. I need to be smacked for continuing to pick them up. I'm trying to get rid of some parts that I've accumulated, but I keep adding more parts.

[tom66]

Re: Vizio P42HDTV10A with LG internals shutting off after 15 seconds.

Newer ones are almost as good as Panasonic picture quality wise and are fairly well built, but the IPM based ones are abysmal.