LG 60pk550 turning on and off

[dejesus]

Hi, everyone. It been quite some time I don't start a thread, most of the time you can find the information in the forum. I look for my problem but still have some doubt . I got a Lg 60pk550 from a friend that was going to get rid off. The tv turn on and off in a continues circle, you can see the screen when it on but will immediately shut off and start all over again. You can hear a click when it turn on and almost immediately another click and shut off. I have unplug each board, one by one, plug the tv, still same thing, two click and go into circle. The only board that it does only one click is when i disconnect the main board. I am incline to believe that i have a bad main board. I have put some picture of the back of the tv. If some one can help me it will be really appreciate.

[Hamie]

Re: LG 60pk550 turning on and off

It's not going to turn on without the main board connected.
The mainboard sends the RL-ON and M-ON signal to the power supply.

With a resistor (100ohm) connect RL-ON to 5vstby.

What voltage do you get at VS and VA?

[dejesus]

Re: LG 60pk550 turning on and off

thank you for reply. When i put a resistor va go to 200v and vs to 59v

[Hamie]

Re: LG 60pk550 turning on and off

I take it you mean that VS is 200v and VA is 59v

If it's the other way around you have a problem!

[Hamie]

Re: LG 60pk550 turning on and off

Ok so leave the resistor in place just now.

Disconnect the LVDS cable that connects the Main AV Board to the Control Board (t-con).

Now with a paper clip or piece of wire connect the 2 holes on the control board marked EXT_AUTO_GEN

If it's not marked, it's usually 2 holes beside R51 and R52, or R501 R502.

Your picture isn't of good quaility but I think the 2 holes are located here:



Plug in the tv, it should now power on and display test patterns.

Does it?

[dejesus]

Re: LG 60pk550 turning on and off

Good morning. I am more awake now. Ok, you are right, vs 200 and va 59. The issue is that i get that without having the resistor put on but in both cases with it on or off the voltage drop. still hear the two click. The test that you mention i already did it last night and nothing happen, still hear the two click sound. in the first click the tv will start and you can see a white screen immediately it click again, it turn off. It will not stay on.

[dejesus]

Re: LG 60pk550 turning on and off

What should be my next step?

[Hamie]

Re: LG 60pk550 turning on and off

With the resistor in place the power supply should stay on.

The vs and va shouldn't drop off.

Have you checked for bad solder connections?

[dejesus]

Re: LG 60pk550 turning on and off

yes i did. I even check the capacitors.

[Hamie]

Re: LG 60pk550 turning on and off

If you link up 5vstby to RL-ON
And also 5vstby to M-ON

Do the voltages stay up?

[dejesus]

Re: LG 60pk550 turning on and off

Good evening, and thank you for taking your time in helping me get this tv going. It is 12:30 am here in Florida but I will take a few minutes and give it a try and let you know what happen.

[dejesus]

Re: LG 60pk550 turning on and off

I did as you said. I put the two resistor 5vstby to RL-ON and 5stby to M-ON but still wont stay on. I am going to take a picture of the power supply back and front to see if you can see something that i may be missing

[dejesus]

Re: LG 60pk550 turning on and off

I did check the solders again and i just can't find anything suspicious

[Hamie]

Re: LG 60pk550 turning on and off

I take it that with the jumpers in place you have unplugged it at the mainboard end?

It's a strange way that you have done that.

I would have put the resistors in more like this.

[dejesus]

Re: LG 60pk550 turning on and off

Got it. Yes the main was unplug. What will be my next step.I check everything that I may know and i can't find the source of the problem. Appreciate your help.

[Hamie]

Re: LG 60pk550 turning on and off

the problem is your power supply isn't staying on.
I can only give you advice but really finding the problem will be down to your own fault finding ability.

Check and make sure that all voltages going to the main AV board are present (17v etc) and not fluctuating.

Reflow all joints on parts attached to heatsinks. Resolder transformers and coils.

The 50" versions of these Tvs suffer from either one of the 3 wirewound resistors failing (located in top right of the power supply.) test them and make sure they are in spec.

It could be a faulty regulator, these can sometimes be easily found with a can of compressed air turned upside down and freeze them. If the power supply turns on and stays On with them frozen then change it out and best to change any parts in circuit with the regulator.

The smaller caps on lgs fail all the time but will look good. Try heating up the caps with a hair dryer then applying power once they are hot.

Good luck.

[dejesus]

Re: LG 60pk550 turning on and off

Good Morning Hamie. Thank you for reply. This is all very interesting, I don't know much about technology but i am a quick learner and i like challenge. You had give me plenty idea of what to look for. I will follow your instruction step by step. I am looking forward to give you good news. Will keep in touch, once again thanks.

[Hamie]

Re: LG 60pk550 turning on and off

pay particular attention to these.

R108
R109
R110
R111
R112
R113

[Hamie]

Re: LG 60pk550 turning on and off

check these.

[dejesus]

Re: LG 60pk550 turning on and off

ok. i will do it right now. i got the spray.