LG UF6450 half screen is black, half is blue/white

[nomoresonys]

Re: LG UF6450 half screen is black, half is blue/white

That's a good question, maybe some of the guys familiar with these UF's can advise, seems kind of scarey with the XDA engine BGA chips being known to fail way too early and mainboards being so scarce and expensive.

[budwich]

Re: LG UF6450 half screen is black, half is blue/white

If the tcon board replacement had no effect. Is the next thing to go to is the main board or am I just throwing money away? I see the tcon ribbons attach to another board assuming that is the lcd. Could it just be a bad lcd?

there are some VCOMxxxx points near the tcon to panel connectors... you might check and list those also. Further, some of those voltages that you already posted can be found / should be found on the bottom edge / driver boards of the panel. You might also check some of those.

[budm]

Re: LG UF6450 half screen is black, half is blue/white

At this point I would check the resistance of MLCC's (Multi Layer Ceramic Capacitor) on the tab bonding board, it does not cost any money to do that.

[jskuyper]

Re: LG UF6450 half screen is black, half is blue/white

At this point I would check the resistance of MLCC's (Multi Layer Ceramic Capacitor) on the tab bonding board, it does not cost any money to do that.

What should these values be

[jskuyper]

Re: LG UF6450 half screen is black, half is blue/white

there are some VCOMxxxx points near the tcon to panel connectors... you might check and list those also. Further, some of those voltages that you already posted can be found / should be found on the bottom edge / driver boards of the panel. You might also check some of those.

Vcomrfb 5.64
Vcom1 5.68
Vcom2 5.9

[nomoresonys]

Re: LG UF6450 half screen is black, half is blue/white

What should these values be

Check them in ohm mode, probably be suspicious of any under 100 ohms or so.

[Unspun01]

Re: LG UF6450 half screen is black, half is blue/white

This TV has a bad mainboard. In fact, the main IC (IC100) under the black heat sink in center of board has failed. IC100 is a Ball Grid Array IC part number LGE5332 (XD Engine). My mainboard is EBT64048902, with TV model 55UF6450.

Either replace the mainboard, or replace the IC.

Re-flowing or re-balling the IC will not work.

This appears to be a common failure mode of similar LG 4K LED TVs. I've seen a few 55" LG 4K LED TVs that use same IC and similar issues.

On my TV, I had one side with video, and one side not, often there was snowy picture, and even flickering. Could not get video on HDMI if I recall it only got black/white video through component/composite? The symptoms presented as a bad TCONN or a bad panel, but it was the mainboard that was bad.

I got a good deal on a working replacement mainboard, but I bought a couple LGE5332 ICs on aliexpress.com for reasonable price in case I need to do BGA replacement

Be wary of buying a used board since many resellers may think the TV has a panel issue and sell the mainboard as working but may actually be bad mainboard. I was lucky that mine was a good one. It would be helpful to ask for a photo of the TV screen showing video, (even with cracked panel)

Here is a link to another thread on this issue:

https://www.badcaps.net/forum/showthread.php?t=70107

Apparently there is a revised board that addresses the issue, but I cannot recall the new part number.


Reason for edit: I typed the wrong part number.

[jskuyper]

Re: LG UF6450 half screen is black, half is blue/white

Found a new main board but continue to have issues. The screen will sometimes be all black and other times split with two colors or all static

[jskuyper]

Re: LG UF6450 half screen is black, half is blue/white

I guess it makes a difference mounting the mainboard down

[Davi.p]

Re: LG UF6450 half screen is black, half is blue/white

First of all i think Unspun is right, but to be more precise it lacks some testpoints in tcon, Vgl1 & 2, VGH even & odd, the showed video tells of a lacking of a signal from mainboard to tcon where there is Hsync, you can also test it with the help of a screen datasheet or also without. I'm on a cellphone so i can't help you.
For the new chips found on Aliex i can say that almost surely them are used chips removed from boards.. and not surely working...