LG 50pk950 psu issue

[seraph]

Hey guys first subject thread for me here so please bear with me! I'm not super familiar with electronics, but I'm learning so here goes!

I picked up an lG 50pk950 last week, pretty cheap not working thinking it would be a good project to undertake, I've read around the net trying to isolate the problem and I believe its the psu.

If I turn it on after being unplugged for a while it'll power up but at most 20 seconds but then it clicks off and only click the relays when trying to turn on. Same 3 clicks when everything is disconnected except the ac to psu. I Have checked the 3 10 ohm ceramic resistors and they're fine, D304 is fine off the board, f302 is fine. Does ic301 always take out d304 and f302 when it goes??

Caps all look fine (unsure how to test) all other ceramic resistors read fine.

Anything else commonly go wrong on these boards?

Thanks!

[sordids999]

Re: LG 50pk950 psu issue

Posting pictures of the back of your tv showing the boards with clear pictures may help you more with fixing your problem

[Hamie]

Re: LG 50pk950 psu issue

If the TV powers on occasionally its not IC301.

It's more likely ic701.
Use freeze spray on ic701 and see if it turns on.

[seraph]

Re: LG 50pk950 psu issue

I wish I could put up photos, but since i slammed my phone in a car door unfortunately I'm cameraless!

But the board is this one


Freezing ic701 didn't change a thing :/ still the usual. Initial power up gets to no signal, then switches off and click click click...usually haveto wait atleast a day before it'll get as far as no signal again. Totally perplexed.

[sordids999]

Re: LG 50pk950 psu issue

Possible fault:
All supply voltages will come up then die
Intermittent going on and off and clicking
will work for 20 mins then will go off and start clicking*


If heating/cooling ic701 makes no difference*

check R103,R104,R105,R106,R107,R108,R109,R110,R111,R112, R113

hope this may help

[seraph]

Re: LG 50pk950 psu issue

Possible fault:
All supply voltages will come up then die
Intermittent going on and off and clicking
will work for 20 mins then will go off and start clicking*


If heating/cooling ic701 makes no difference*

check R103,R104,R105,R106,R107,R108,R109,R110,R111,R112, R113

hope this may help

None of them are dead, what are the values supposed to be?

[ljintexas]

Re: LG 50pk950 psu issue

Maybe try some heat ?

[sordids999]

Re: LG 50pk950 psu issue

none of them are dead, what are the values supposed to be?

r103,r104=240k
r105,r106=150k
r107=100k
r108,r109,r110=680k
r112=620k
r113=560k

[seraph]

Re: LG 50pk950 psu issue

r103,r104=240k
r105,r106=150k
r107=100k
r108,r109,r110=680k
r112=620k
r113=560k

r103; 215k
r104; 225k
r105; 145k
r106; 146k
r107; 99.8k
r108; 590k
r109; 530k
r110; 590k
r112; 551k
r112; 455k

Obviously some of these are looking a little low, likely to be causing an issue?

[seraph]

Re: LG 50pk950 psu issue

r103; 215k
r104; 225k
r105; 145k
r106; 146k
r107; 99.8k
r108; 590k
r109; 530k
r110; 590k
r112; 551k
r112; 455k

Obviously some of these are looking a little low, likely to be causing an issue?

Should replacing these solve the issue??