LG 55UF6450 No Backlights

[eagle00799]

Re: LG 55UF6450 No Backlights

I just might try that Diah, This exact board is pretty hard to find.

[Andrew F. Ali]

Re: LG 55UF6450 No Backlights

hmmm. most always tinny small boards from LG need heating later , as they used at manufacturing halogen free since 2015.

use hot air or backing offen ( with out air fellow ) to rebel the main board .. or just the reheat the main processor

I have used a Hot air Station to blow 375C at speed 4 for 10mins on the BGA chip of probably 5 or 6 LG TVs in the not too distant past and they worked and as far as I know are still working.

[eagle00799]

Re: LG 55UF6450 No Backlights

Ok I sent my main board in to PTS Electronics for repair and they say they found nothing wrong with the board during testing so they are sending it back, should be here sometime today. Do I take their word for it or do I try Hot air on the BGA chip anyway?

[Diah]

Re: LG 55UF6450 No Backlights

dont heat or play any things with your main boards.. first of all i suggest you take the LCD in part till the LED, i am sure you will find the issue there

[budwich]

Re: LG 55UF6450 No Backlights

back a way, you did a test by unplugging the small cable on the tcon and the backlights came on. Can you do a similar test, but this time leave the small cable connected and disconnect both of the tcon to panel cable at the same time... what happens when you power up?

[budm]

Re: LG 55UF6450 No Backlights

Per post #1: P-DIM1=0, P-DIM2=0 are 0V, but you have BL-ON signal (DRV-ON).
That small connector on the T-CON is more likely to be for dimming control, you are able to get the backlights to come on by disconnecting that small cable, you should then check the Voltage aging on those Dim control pins to see what you have.
Since you are able to get the light source to come on, then you should see pictures if the main board, T-CON board, and the panel are OK.
Can we also see the pictures of the whole backside of the TV showing how all the boards are connected together?

[eagle00799]

Re: LG 55UF6450 No Backlights

Budwich, I disconnect both ribbons from tcon to panel and I get sound but no pic,no flash of backlights.

[eagle00799]

Re: LG 55UF6450 No Backlights

Budm, I get 3.26v on both DIM1 and DIM2 pins with small connector unplugged and 2.5mv on both pins when plugged in. Now that I got this main board back in I can not get the TV to switch inputs or find the DVD player, all I get is static sound for a while then it stops completely for a while then the static sound comes back on.

[eagle00799]

Re: LG 55UF6450 No Backlights

Pic of lay out

[eagle00799]

Re: LG 55UF6450 No Backlights

Sorry the pic is upside down. Just a note here, there is a red light that is on steady on main board.

[eagle00799]

Re: LG 55UF6450 No Backlights

Well I have had the main board checked twice and it's working so I orded a tcon board and installed it today and I get the same issue, no changes. any idea's where to go from here? I also checked the backlights and all are working so they appear to be fine.