LG LCD LED x 2 Mainboard Fault?

[happyade123]

HI ALL. I have two Lg Led Lcd Televisions that I have diagnosed the main board as being FAULTY. The first is a 37LV3730 which came in with the reported fault of red smearing while watching television and dvds etc. I hooked it up and sure enough it was flaring little sparkling red bits in random spots across the screen, very noticeable on a red background.
The second tv is a 42LV3730. The main difference that I can see between the two is the size of the screen. This 42 inch switched on but did not turn on the inverter etc and no voltage was fed to the tcon fuse despite the fuse being ok and 12 volts being present on the mainboard.This tv therefore produced no image not even a flash in the dark with a torch etc.
I was fairly certain the mainboard was the issue so I removed the one from the other tv and fitted it and sure enough it came to life, except now it has the flaring etc so the fault has transferred to the other one, which makes me think this fault is also a mainboard.
I upgraded the firmware and the software on this model performed picture diagnostics etc and still the red flaring remains. I can't seem to source a replacement mainboard anywhere so I am hoping to fix one or both of these tvs. Any ideas on what could be causing the mainboard to have these fault conditions?
I have included two pictures the first is showing the fault as a closeup during the Picture Wizard setup. The second is just the general setup screen used during Picture Wizard.

[diif]

Re: LG LCD LED x 2 Mainboard Fault?

LV picture issues point to a faulty BGA under the main processor.

[happyade123]

Re: LG LCD LED x 2 Mainboard Fault?

Is this fixable Diif or do I need another mainboard?

[diif]

Re: LG LCD LED x 2 Mainboard Fault?

The proper way is to reball the chip, but they can be reflowed.
There are plenty of people that have reflowed with either a paint stripping gun or by baking in the oven if they don't have a hot air station or BGA rework machine. Be careful with either of these methods as they can both kill the mainboard beyond repair. The paint gun being to hot and the oven melting plastic components.

[happyade123]

Re: LG LCD LED x 2 Mainboard Fault?

I have a hot air station but have limited expertise with using it diif. What is reballing?

[diif]

Re: LG LCD LED x 2 Mainboard Fault?

The chip is removed. The solder balls that attach the chip to the board are removed and new ones replaced, before resoldering to the board.
Considering you have a board that's almost working, I'd attempt a reflow on that first. Apply flux around the chip first before applying heat. Do you have a preheater ? If you can heat the board all over to about 100C before applying top heat, it is much easier and less likely to damage the board.

[happyade123]

Re: LG LCD LED x 2 Mainboard Fault?

I assume I don't have a preheater Diif as I have no idea what it is lol? Do you have any ideas for the board with no power?

[diif]

Re: LG LCD LED x 2 Mainboard Fault?

You could try pressing on the main chip that has the red flaring with the tv on and see if this changes the image at all.

[happyade123]

Re: LG LCD LED x 2 Mainboard Fault?

The customer has decided to tolerate it the way it is. I have made it more watchable with some adjustments. I would like to fix the one with no power though if possible Diif as it is the bigger screen.