LG 42LG5010 - Bad T-Con ?

[unit22]

Hi all, recently acquired this TV, hoping to get it back working again (for my own use).

Symptom: Bright/White screen, can just about see image but very bright.

The T-Con board is T420HW02 - 42T04-C04, I have read (on this forum) that the AS15 chip is prone to failure.

I have done the voltage test as instructed in another thread and these are my results:

VGMA22 - 7.05v
VGMA20 - 8.99v
VGMA18 - 9.49v
VGMA16 - 12.52v
VGMA14 - 3.68v
VGMA12 - 1.43v
VGMA10 - 1.36v
VGMA8 - 5.10v
VGMA6 - 7.63v
VGMA4 - 14.90v
VGMA2 - 15.53v

VGMA21 - 9.17v
VGMA19 - 11.24v
VGMA17 - 10.70v
VGMA15 - 13.38v
VGMA13 - 1.45v
VGMA11 - ....... Around +2.0v (increasing and decreasing around 2.0v)
VGMA9 - .........Around +2.0v (increasing and decreasing around 2.0v)
VGMA7 - 6.00v
VGMA5 - 11.63v
VGMA3 - 15.50v
VGMA1 - 15.56v

VCOMF - 6.32v
VCOM - ........ Around +3.0v (increasing and decreasing around 3.0v)
V303 - 3.30v
AVDD - 15.72v
AVDD_F1 - 15.77v

VGMA - 15.47v
VGHC - NIL
VGL - -6.03V (minus 6.03v)
VGH - NIL
YV1C - 2.64v
INSDA - 3.26
12VIN - 11.91

Can someone please decipher these fiquires for me, I have no idea what they should be. Thank you for any help

[tom66]

Re: LG 42LG5010 - Bad T-Con ?

The gamma chip is definitely bad. The voltages from VGAMA1 to VGAMA22 should either rise or fall slowly but only one way.
e.g. 1,3,5,7,9V is OK and 15,10,5,2,1V is OK, but 1,3,2,7,4,10V is not good.
That's the gist of it - there's a bit more to it but that finds most failures like this one.

[unit22]

Re: LG 42LG5010 - Bad T-Con ?

The gamma chip is definitely bad. The voltages from VGAMA1 to VGAMA22 should either rise or fall slowly but only one way.
e.g. 1,3,5,7,9V is OK and 15,10,5,2,1V is OK, but 1,3,2,7,4,10V is not good.
That's the gist of it - there's a bit more to it but that finds most failures like this one.

Thanks for the help tom, much appreciated :-) And thanks for the explanation too, always willing to learn!

So i need to get a used but working t-con board then! I will report back when it arrives, thanks again

[tom66]

Re: LG 42LG5010 - Bad T-Con ?

If you have good soldering technique you can also replace the AS15-F chip.

[unit22]

Re: LG 42LG5010 - Bad T-Con ?

If you have good soldering technique you can also replace the AS15-F chip.

Thought about that tom, but I am not confident in soldering such a small chip lol It is tiny! Soldering parts on the PSU is my limit at the moment

I do know a guy that can replace the IC chip, but hasn't got back to me on a price. How much do people charge for this repair?

Cheers

[unit22]

Re: LG 42LG5010 - Bad T-Con ?

Hi
Thanks again tom, again you were spot on with your advice! The T-con board arrived yesterday and now the TV is working lovely! Really appreciate the help, thanks!!!