LG42PQ3000-powers up & cuts out

[Cornboats]

I'm going round in circles with this one.
TV powers up. Channel station number displays sometimes with sound.
Click on menu, menu displays for milliseconds, power turns off.
VS=195v, Va=60v, 5V=4.9v, ZA 75v(should be 80V)
I've replaced;
Y sus, Z sus boards,psu and ysus buffers
That only leaves bottom buffers and lvds/t-con

Any help or advice welcome.

[tom66]

Re: LG42PQ3000-powers up & cuts out

Does the relay click off when this occurs? Screen glowing or not?

[Cornboats]

Re: LG42PQ3000-powers up & cuts out

Hi Tom
On power up , relay clicks in, green light comes on, I get a picture and sound for about a second then relays drop out.-red light comes on.

Heres a pic of tv on for that split second with sound. Its not a full picture of the station only a picture of the station number which shows in the top right of screen. For a short while when I got this far I managed to go into the menu bar then when I clicked on setup it powered down.

Thanks for showing some interest.

[tom66]

Re: LG42PQ3000-powers up & cuts out

I have an LG 42PQ2000 here which is now working. The PQ3000 just has movie capability via USB and a few other features.

There is a main board, with the video inputs on it, and a board in the middle of the set - the control/logic board. On the control board, there is are two points marked EXT AUTO GEN. Please place a wire jumper between the two holes, and disconnect the LVDS cable which runs between the main and control boards.

You should get some patterns showing up, do you?

[Cornboats]

Re: LG42PQ3000-powers up & cuts out

Hi Tom
I soldered a link wire to the holes & disconnected lvds cable going to the main board.

Standby goes to blue, relays click on screen shows signs of life -backlight only then relay clicks off,standby stays blue,after a couple of secs standby goes red. Cycle repeats itself as long as power remains to the set.

Hope thats been of some help.

[tom66]

Re: LG42PQ3000-powers up & cuts out

Can you show me which cable you unhooked so I can be sure it's the right one?

[Cornboats]

Re: LG42PQ3000-powers up & cuts out

heres 2 pics to confirm.
If the patterns were displayed would that confirm the y sus and z sus are ok?

[tom66]

Re: LG42PQ3000-powers up & cuts out

That is the correct cable, you did press power button and TV light went blue right?

[Cornboats]

Re: LG42PQ3000-powers up & cuts out

Yes thats right.
Power button on
relay click -blue light comes on- screen lights upfor millisceconds, but no picture,sometimes sound -relay is heard clicking-red light comes on.
If the power button is left on the tv just cycles as above.

[tom66]

Re: LG42PQ3000-powers up & cuts out

Might have to jumper the PSU then - do you have a pair of 100 ohm resistors available?

[Cornboats]

Re: LG42PQ3000-powers up & cuts out

Yes -0.5watt 100 ohm
Let me know what your thinking -What board are you suspecting as faulty?

[Cornboats]

Re: LG42PQ3000-powers up & cuts out

So which terminals do I short out with these resistors?

Maybe I should start again and try and eliminate 1 board at a time.
Anybody any ideas?

[tom66]

Re: LG42PQ3000-powers up & cuts out

PSON and VSON to 5V Standby. If there is an M5V_ON or RL_ON jumper that too.

[Cornboats]

Re: LG42PQ3000-powers up & cuts out

Is this to get a pattern from the control board?

I can't find PSON and VSON to 5V Standby. I'll upload the only 2 connectors on the smps board.

I've got M5V on & RL on. Do I jumper these to the 5v standby or to themselves with the 100 ohm resistors?

Do I refit the connector from the main board-if so I need to solder jumpers underneath.