LG 42LW4500-LB Need help with repair of PSU

[WTRWLKR]

Re: LG 42LW4500-LB Need help with repair of PSU

Hi vahid114,

You may want to start a new thread. This one died over a year ago.

[happyade123]

Re: LG 42LW4500-LB Need help with repair of PSU

Is this guy for real. No offence . Mate you have been given some very clear instructions and only measuring low voltage instead you are opting to measure the higher more dangerous voltages. Personally I think you would be better off putting the cover back on and take it to someone who knows at least where the power switch is and how to do basic troubleshooting. Just because the power supply is on one board does not mean it automatically runs all the time. It requires other voltages and signals from other boards to allow all the different, voltage rails to turn on. Bud M has given you excellent advice. Measure the PS on voltage between ground and the ps on pin of power supply. If you don't feel confident just hook up Jumper clips to ground and a component off the ps on pin. Put your metre on dc not ac. Do you have a picture of your metre? Willing to help more but not if there is a risk of endangering your life. Even your electrotechnical teacher (as you put it) would dissuade you from touching it , unless of course this is some kind of joke , then you are just wasting people's time.

[vahid114]

Re: LG 42LW4500-LB Need help with repair of PSU

Hi, please help me to find the r123 resistance number on the power board LG 47lw4500

[Andrew F. Ali]

Re: LG 42LW4500-LB Need help with repair of PSU

I really think this person is toying with our good intention....Sometimes not all threads are real.....I detect a mischief maker here.....Just can't follow a simple instruction...then go and do something that makes no sense and ...voila...it comes ON....Sheeeeesh....Anyway budm....you certainly have the virtue of patience....I would have given up a long time ago.....just reading this post makes my head ache......Thanks.

[budm]

Re: LG 42LW4500-LB Need help with repair of PSU

Well, you are not making any sense since as explained, the MOV is connected in parallel with the cap which you have measured 230VAC between the cap's legs, the MOV has nothing to do with the TV functioning, more likely you have disturbed bad connections or connectors that may not be seated properly or loose mounting screws holding the board to make the GND connection to the chassis, etc..

[UndeadLuke]

Re: LG 42LW4500-LB Need help with repair of PSU

Well what do you think?
Post 39: "Where I can found the power switch ? It will be good if you have some scheme for this board ."
Post 42 "I will try to remove the surge protection" still try to deal with MOV after all the explanation?
We are over 40 posts now an still no answer on the PWR-ON signal pin. If there is no PWR-ON form main board then the Main board will have to be checked, but at this we do not know if we have that signal or not. May be after he finds the Power switch?

I just remove the surge protection and TV starts LCD shine i also hear click of rele so maybe i will try to do this with this surge protection again .. and chill man I know Iam dumbass maybe but i made progress and it starts shine before it do nothing just turn off imidietly

[budm]

Re: LG 42LW4500-LB Need help with repair of PSU

Someone needs a chill pill

Well what do you think?
Post 39: "Where I can found the power switch ? It will be good if you have some scheme for this board ."
Post 42 "I will try to remove the surge protection" still try to deal with MOV after all the explanation?
We are over 40 posts now an still no answer on the PWR-ON signal pin. If there is no PWR-ON form main board then the Main board will have to be checked, but at this we do not know if we have that signal or not. May be after he finds the Power switch?

[syaoran123]

Re: LG 42LW4500-LB Need help with repair of PSU

So far I asked you to provide simple DCV reading of the PWR-ON pin on post 26 but insisting on replacing the MOV. WHY? THE DAM THING IS NOT BAD! GET IT!
I WASTED MY TIME ON THIS THREAD WHEN YOU CANNOT EVEN FOLLOW THE INSTRUCTION!

Someone needs a chill pill

[budm]

Re: LG 42LW4500-LB Need help with repair of PSU

So far I asked you to provide simple DCV reading of the PWR-ON pin on post 26 but insisting on replacing the MOV. WHY? THE DAM THING IS NOT BAD! GET IT!
I WASTED MY TIME ON THIS THREAD WHEN YOU CANNOT EVEN FOLLOW THE INSTRUCTION!

[syaoran123]

Re: LG 42LW4500-LB Need help with repair of PSU

The mainboard is a common fault. Just saying its a possibility. All you need is to to heat up the large heatsink with a hair-dryer on highest heat for 2 minutes and turn on. Let me know if it doesnt work, then we can move on to psu

[UndeadLuke]

Re: LG 42LW4500-LB Need help with repair of PSU

Do you mean all these time you do not know where the power switch is? So how in the world you know that the relay is working?
How about going to LG website and down load the user manual?

I need service manual for board scheme :/

[UndeadLuke]

Re: LG 42LW4500-LB Need help with repair of PSU

Do you mean all these time you do not know where the power switch is? So how in the world you know that the relay is working?
How about going to LG website and down load the user manual?

So you telling me i need to coonect the man
Inboard and everything else and try to pit on 230vac try to set on tv and after thst i need to look for bad part ? I will try to remove the surge protection and i will check the board under voltage again if the voltage will go after because now i have voltage only on main gray filter cap i will replace the surge protection with cable for test

[budm]

Re: LG 42LW4500-LB Need help with repair of PSU

Where I can found the power switch ? It will be good if you have some scheme for this board .

Do you mean all these time you do not know where the power switch is? So how in the world you know that the relay is working?
How about going to LG website and down load the user manual?

[budm]

Re: LG 42LW4500-LB Need help with repair of PSU

I really dont understand you opinions because why I dont have no power on main power circuit ? I think the relay turns on when I press power button but i dont have any power on my primary circuit market like 1 on board. also no power after this red market part so firt gray cap is with power but the second one is without because it looks like the part got damaged like when you damaged fuse . its surge protection i know but when surge protection fails like fuse and got damaged you will have no power after it ? Isnt that true ? and yes I will follow the instructions .

The MOV is connected across the power line after the fuse, it will heavily conduct and causes the main AC fuse to blow, like I said it is not need to for the TV to function! You can even remove it! you just will not have surge protection. It is not connected in SERIES like a fuse, it is connected in parallel with incoming AC.
Look up and learn what the MOV is for and how it is used then you will understand.

You think the relay is turned on, how did you figure that out? it has DCV on the relay coil when the power switch is activated and the Voltage is there and did not drop out.
Did you even verify that you do have DCV at the PWR-ON pin as I asked.
It sounds like you are skipping in learning the basic as to how the component functions.

[UndeadLuke]

Re: LG 42LW4500-LB Need help with repair of PSU

OK, so far you do have standby Voltage otherwise based on Post #1 "Hi guys today my TV stops working (it woudnt turn on only led shine so the power goes into it)"
Looking the board layout, you will not have any DCV between the two legs on any of the filter caps C612~C614 until you have > 2VDC at the 'PWR-ON' pin of the connector P201 to turn on the power relay RL101 to supply the 230VAC to the bridge rectifier BD101.
So check and see if you have DCV at 'PWR-ON' pin or not when the power switch is activated.

Where I can found the power switch ? It will be good if you have some scheme for this board .

[UndeadLuke]

Re: LG 42LW4500-LB Need help with repair of PSU

The main board has to send the PWR-ON to turn on the relay, no command signal = no relay action.
You have to follow the instruction.

I really dont understand you opinions because why I dont have no power on main power circuit ? I think the relay turns on when I press power button but i dont have any power on my primary circuit market like 1 on board. also no power after this red market part so firt gray cap is with power but the second one is without because it looks like the part got damaged like when you damaged fuse . its surge protection i know but when surge protection fails like fuse and got damaged you will have no power after it ? Isnt that true ? and yes I will follow the instructions .

[UndeadLuke]

Re: LG 42LW4500-LB Need help with repair of PSU

I am not convinced unless you support your claim. Do you even know how to test a fuse? Have you tried heating the mainboard with a hair-dryer?

I know how test fuse .. if beeps its good ... i tryed it and all of them are Ok heating ? man this is not bad chip

[budm]

Re: LG 42LW4500-LB Need help with repair of PSU

All fuses are Okey main AC fuse is before this little b*tch I want to know what is it and what i can replace it iam agry of it as I sed I had no voltage after the part I will mark it on anotherpost I cant get no voltage on the relay so relay cant switch the voltage to diodes when you press power button it will imidietly turn off TV so i cant turn it on i think the marked part is definetly bad please tell me what it is and what can i replace with it :/

The main board has to send the PWR-ON to turn on the relay, no command signal = no relay action.
You have to follow the instruction.

[syaoran123]

Re: LG 42LW4500-LB Need help with repair of PSU

Its faulty .. I checked all fuses and they are OK .. all of them

I am not convinced unless you support your claim. Do you even know how to test a fuse? Have you tried heating the mainboard with a hair-dryer?

[budm]

Re: LG 42LW4500-LB Need help with repair of PSU

Read post 26 again and report the reading.