LG 42LC46 problem

[ReeceyBurger123]

Re: LG 42LC46 problem

I Know this is an old thread but I had the same problem as the OP. The TV would power on when cold but after 2 mins the picture would go off, sound and back light still on. Using the hairdryer trick I thought I had found the problem C954 - 470uF ( top left corner ) I changed that and all was well. So I thought, the TV did not go off. I left it on for about 1.5 hours then turned it off and on again, no picture again. Having scoured the internet I found a site that offered a repair kit for for such problems which showed the capacitor numbers. I changed C975 -100uF ( near T-Con connector ) the TV seems to be working as it should :-).
The capacitors listed on the site are.
C553 - 100uF
C901 - 100uF
C915 - 100uF
C954 - 470uF
C970 - 100uF
C975 - 100uF
I hope this helps other people with the same problems

Thank you sooo much this helped me repair one I have

[Scoots]

Re: LG 42LC46 problem

I Know this is an old thread but I had the same problem as the OP. The TV would power on when cold but after 2 mins the picture would go off, sound and back light still on. Using the hairdryer trick I thought I had found the problem C954 - 470uF ( top left corner ) I changed that and all was well. So I thought, the TV did not go off. I left it on for about 1.5 hours then turned it off and on again, no picture again. Having scoured the internet I found a site that offered a repair kit for for such problems which showed the capacitor numbers. I changed C975 -100uF ( near T-Con connector ) the TV seems to be working as it should :-).
The capacitors listed on the site are.
C553 - 100uF
C901 - 100uF
C915 - 100uF
C954 - 470uF
C970 - 100uF
C975 - 100uF
I hope this helps other people with the same problems

[rmoody]

Re: LG 42LC46 problem

Well, i've fixed the power board that the customer messed up by cutting a small staple and soldered it to a trace connecting to the positive side of that capacitor. Seems to be working just fine, not the best looking thing but hey it works.

[rmoody]

Re: LG 42LC46 problem

I've never looked for them before - perhaps digikey or mouser? I'm on my iPhone right now but will have a look when I return home (out picking up a 42" HD LCD with cracked screen for free - now missus wants to do some shopping!)

Can't beat free, nobody want's to give shit away over here.

[bbjunkie]

Re: LG 42LC46 problem

I've never looked for them before - perhaps digikey or mouser? I'm on my iPhone right now but will have a look when I return home (out picking up a 42" HD LCD with cracked screen for free - now missus wants to do some shopping!)

[rmoody]

Re: LG 42LC46 problem

Could it be repaired? Pace have some really good videos on circuit board repair on youtube. http://www.youtube.com/watch?v=7o4ZWlG6mmo

I watched some of those videos but not sure if the kit will be worth the time and money. It's not mine anyways, since the guy broke it, i'm leaving it up to him to find a board. Do you know where to find those kits? Radio shack is the best thing i've got around here and it's 30 minutes away.

[bbjunkie]

Re: LG 42LC46 problem

Could it be repaired? Pace have some really good videos on circuit board repair on youtube. http://www.youtube.com/watch?v=7o4ZWlG6mmo

[rmoody]

Re: LG 42LC46 problem

Well I attempted repairing the missing solder pad today with a circuit writer pen but it didn't help any. I'm pretty sure my problem is from the power supply. The darn things are hard to find too.

[rmoody]

Re: LG 42LC46 problem

Found something interesting. I noticed when powering up the tv the video looked fine for just a second and then it cuts out to no signal for about 10 seconds and comes back on distorted. I started checking some of the pins going to the main board and one stood out, it's the VBR-B. There's a VBR-A that reads 3.3V but VBR-B was only reading 2.7v. I jammed my probe into the VBR-B and powered it on from a cold shut down. When the tv first powers on and the display is good, I get 3.3 volts on the VBR-b pin and then it zeroes out while the no signal was displayed and then when the distorted picture comes back on the voltage is only 2.7V

[tom66]

Re: LG 42LC46 problem

Any way to check this without swapping boards? I would think the EEPROM can't just be replaced without being programmed, Right?

Not necessarily... most TVs will reprogram the EEPROM with default factory settings if a blank one is replaced.

[rmoody]

Re: LG 42LC46 problem

I think this is actually a 42LC7D. He brought it to me with the back off so I can't confirm the actual model.

[rmoody]

Re: LG 42LC46 problem

Hi there..if ur set is the same model as mine(LG 42LC46) your main board is different to mine..damn that soldering is bad..

Bad isn't the word for what that is, he massacred that board.

[sienoki]

Re: LG 42LC46 problem

Any way to check this without swapping boards? I would think the EEPROM can't just be replaced without being programmed, Right?

Hi there..if ur set is the same model as mine(LG 42LC46) your main board is different to mine..damn that soldering is bad..

[rmoody]

Re: LG 42LC46 problem

It's quite possible the EEPROM has become corrupted and in the process has messed up some very important picture settings - common on Samsung TVs with bad caps.

Any way to check this without swapping boards? I would think the EEPROM can't just be replaced without being programmed, Right?

[tom66]

Re: LG 42LC46 problem

It's quite possible the EEPROM has become corrupted and in the process has messed up some very important picture settings - common on Samsung TVs with bad caps.

[rmoody]

Re: LG 42LC46 problem

Also need to mention that even though the picture is distorted, when I press the menu, it comes up looking great. It kind of makes me feel like it's in the main board as the inputs are what's distorted. Also I think if it were the tcon even the menu would look bad.

[rmoody]

Re: LG 42LC46 problem

I would reseat and clean every connection possible with isopropyl alcohol to see if you get any improvement.

Do you think the power supply could be causing the distorted picture?

[rmoody]

Re: LG 42LC46 problem

Here's a look at how bad the soldering looked.

[retiredcaps]

Re: LG 42LC46 problem

Any suggestions would be helpful.

I would reseat and clean every connection possible with isopropyl alcohol to see if you get any improvement.

[rmoody]

Re: LG 42LC46 problem

I think I have the same set. My scenario is the guy that brought it to me picked it up as a freebie and it wouldn't power on. Well he decided to take the back off and go exploring, he found some bulged caps on the PS so he tried replacing them. He got it to power on but it would shut off after 10 minutes. He brought it in to me and I observed that he had reversed polarity on all 8 of the caps he had replaced not to mention a very shoddy soldering job. I removed and replaced all the caps he replaced. One of the caps he removed in a rough fashion and ripped the solder pad off of the pcb. I tried to make the solder stick but it doesn't look so well. Anyways, the tv now powers on and stays on but the picture is horrible. I have posted pics to try and show the quality. I'm at a loss of if he damaged the PS somewhere causing this or maybe it's the main board or tcon. Any suggestions would be helpful.