LG 42LC7D-UB power problem.

[dietzcj]

Re: LG 42LC7D-UB power problem.

LOL no.

[dietzcj]

Re: LG 42LC7D-UB power problem.

I cannot read that tiny label. It appears to be worn off

[tom66]

Re: LG 42LC7D-UB power problem.

I cannot read that tiny label. It appears to be worn off

Are you sure?

All I can remember is it is a synchronous buck converter controller for dual N-channel MOSFETs. Aside from the caps, it could be either dead itself (unlikely) or being held in some kind of shutdown mode (not sure why though.)

Any numbers? Maybe I can jog my memory or browser history, I was repairing this PSU just about 2 months ago.

[dietzcj]

Re: LG 42LC7D-UB power problem.

Trying to locate my magnifying glass.
That little IC is so friggin small.

Did you have to replace that as well ?

[tom66]

Re: LG 42LC7D-UB power problem.

Trying to locate my magnifying glass.
That little IC is so friggin small.

Did you have to replace that as well ?

Nope, just the caps. I'm hoping that the IC is being held in some kind of shutdown mode. Had a similar problem with a Goodmans TV - the controller was getting stuck in protection mode.

[dietzcj]

Re: LG 42LC7D-UB power problem.

Is that your conclusion as well there PlainBill ?

[PlainBill]

Re: LG 42LC7D-UB power problem.

Is that your conclusion as well there PlainBill ?

I don't know. I gave up when it was not possible to view a decent picture of that area of the back side of the board.

PlainBill

[dietzcj]

Re: LG 42LC7D-UB power problem.

here you go.
I appreciate the help, you guys are the best !

[PlainBill]

Re: LG 42LC7D-UB power problem.

here you go.
I appreciate the help, you guys are the best !

Yeah, but we could be better if we had better information. Please understand my position.

I have a 23" monitor. When the picture is opened in a new browser tab, it occupies less than 1/3 of the width of the screen. Downloading it into my picture viewing software, I can expand it to the point where it occupies the full size of the screen. At any magnification, I can read the identifier for the IC - U202. I think the transistor directly above it is Q202, but wouldn't bet more than a quarter at 100:1 odds. I have no idea what the identifier for the other transistor is. As far as determining where the leads of the IC go, the near leads are easy, the far ones are impossible.

I don't feel it is unreasonable to ask for a picture taken from directly overhead, and whose size in the larger dimension is close to 2000 pixels. I don't enjoy telling someone that what he is doing isn't good enough, but I can't help if I can't get the information I need.

PlainBill

[dietzcj]

Re: LG 42LC7D-UB power problem.

I went ahead and bought a Power supply from ebay for $50.
I would like to thank everyone who contributed to my issue here, it is much appreciated.

Chris

[dietzcj]

Re: LG 42LC7D-UB power problem.

I got the new Power supply today and it did not fix the issue. SIGH !

So I will be getting a main board now.

[tom66]

Re: LG 42LC7D-UB power problem.

I got the new Power supply today and it did not fix the issue. SIGH !

So I will be getting a main board now.

Hold on that - could also be an inverter or CCFL issue. Have you tried unplugging the inverter cables? You won't get a picture unless you shine a light at the LCD but you should still get sound. Then see if it lasts a while. If so you have narrowed the problem down to either the inverter or the heat created by it.

[dietzcj]

Re: LG 42LC7D-UB power problem.

I have done all of that troubleshooting.
Unplugged everything including speakers, CCFL's, and the TCON board and the power switch.
To the point that the power supply and the Main board are the only thing plugged in to the power cable.
Thanks though.
Chris

[tom66]

Re: LG 42LC7D-UB power problem.

I have done all of that troubleshooting.
Unplugged everything including speakers, CCFL's, and the TCON board and the power switch.
To the point that the power supply and the Main board are the only thing plugged in to the power cable.
Thanks though.
Chris

Good luck. You may want to talk with the PSU seller and return it - some offer a return service if the parts do not work - also consider that it may be a DOA (dead on arrival) part and look around for another. I've seen main boards cause this problem, but it's more likely to be the PSU.

[dietzcj]

Re: LG 42LC7D-UB power problem.

No such luck on returning that power supply.
I did get my Main board in, but this is defective.
The unit will stay powered on for , well going on 2 hours now. The main board is hosed though because it keeps changing channels or in the menu changing selection, and the remote does not work.
But at least I know what the issue is now.

[marselosm]

Re: LG 42LC7D-UB power problem.

So the problem is the main board not the power suplay?

[dullishpage]

Re: LG 42LC7D-UB power problem.

Was this a mainboard issue, someone on another forum was saying these tvs are prone to overheating and added fans to resolve the issue. I have a tv like this my friend wants me to troubleshoot, doing the same thing. I dont have it in hand yet, but just doing a bit of research real quick to see what others are dealing with in this model.

[syaoran123]

Re: LG 42LC7D-UB power problem.

I have repaired an overheating issue before on these sets. Check the connectors on the mainboard which hold the ribbon cable to the PSU. I believe there were some cold solder joints. The copper ring that binds on to the solder is so small and could easily be cracked.

[dullishpage]

Re: LG 42LC7D-UB power problem.

I did see anything like that, I'll get some photos on here in a bit.