Originally Posted by TheLostBrain
Soo... Did a little exploratory surgery on the UHD420.
Good news! After putting everything back together it still works.
Bad news - Any hopes of "correcting" the backlight diffuser gap behavior mentioned in earlier posts is not really practical.
Oh well, at least learned some cool stuff:
LCD panel: LG LC420EQE (PG)(M1)
Just about an exact match here:
LCD Controller: Kang JIN K-4000
Per spec sheet controller maxes out at 60hz for anything over 1080p...hence why success hasn't been had running at higher refresh rates, etc.
T-Con board: LG TM120 UHD
Interesting, per eBay listings it appears to be same T-con used on the panels in the LG 55UB8500 and 49UB8500.
Although I didn't capture a good picture of it, the reason for the backlight diffuser gap is due to the way LG incorporated the edge lighting in this display. The edge lighting assembly essentially sits on top of the diffuser and would somehow have to be moved out of the way before attempting to bring the backlight and diffuser closer to the lcd. Not to mention the plastic assembly that holds the LG panel together is designed around this and would also have to be modified. Yeah...it would be a pretty involved project to say the least.
Ok, some pics:
LG LCD Panel Assembly Tag
Basically what you see when opening up the UHD420 for the first time
T-Con Board shot 1
T-Con Board shot 2
T-Con Board shot 3
T-Con Board shot 4
LCD Controller shot 1
LCD Controller shot 2
LCD Controller shot 3
LG Panel Assembly showing some spacing. However, this is not the primary cause of the diffuser gap behavior.
LG Panel Assembly partially showing primary cause of the lcd diffuser spacing. You can see how recessed the diffuser film is...However, what you don't see here is that on the other side the edge-lighting assembly sits on top of the diffuser film and is the reason for the recess.
Speakers shot 1
Speakers shot 2
Fun fun fun. Hopefully useful or at least somewhat interesting to a few
Update - For the UHD420 HDMI 2.0 Version I'd say we can pretty safely say Wasabi Mango went with the new K-4500 LCD controller from the same Kang JIN company.
Ports shot from Accessorywhole eBay listing
K-4500 LCD controller shot with same exact ports configuration (minus usb ports - which both the k-4000 and k-4500 actually have support).
From the Timing Table in the specsheet it looks almost an exact match to the K-4000 so I wouldn't expect to much in terms of anything over 60hz when going 1080p or higher.
If you're not looking for hdmi 2.0 specifically I see not much reason in spending more for the newer model. Just my 2 cents... maybe better resell value though?