LG 65UK6090PUA - picture dark

[Danstona]

Was watching this set, and suddenly it went dark. Picture is still visible, just very dark. Tried checking all settings, adjusting brightness to 100% no change. Reset through menus, no change.
bought used boards from ebay (power and input boards) replaced with same results, changing brightness does seem to have a slight affect.. but not to normal visibility of picture.
I'm handy, fixed TVs before.. I can't see any issues with boards... hoping someone can point me in the right direction to properly diagnose. I don't believe the LEDs are caput, since the picture is on and equal across screen for visibility... just too dark.
thanks

[nomoresonys]

Pictures of each board and one including all the boards.

[nomoresonys]

We no longer help people who do not post pictures... maybe that's just me.

[Danstona]

replacement power board

[Danstona]

original power board

[Danstona]

original input board

[Danstona]

replacement input board

[Storyteller12]

My guess is backlights. Especially if you replaced both boards and same symptom. But you need a multimeter and led tester to test the backlights.

[Danstona]

Well I have good multimeter.. I would need to know what the led tester is... with the back off, they light up... I just feel like they should either work or not... not be half bright but still be defective.

[nomoresonys]

So you're saying when you turn tv on you can see the backlights are on, can you very carefully check the dc voltage of looks like C611 the 460 volt capacitor put a probe on each lead, use CAUTION it could be about 400 volts, so watch where you put your hands, you don't want that going thru you, don't do if you're uncomfortable with this kind of testing.

[nomoresonys]

Something to try, heat up looks like C205 500 volt capacitor for a minute or so with a hairdryer, try tv, see if there's any change, don't wait til it cools down, try it while it's still hot.

[nomoresonys]

Since things acted the same, maybe keep original mainboard in for testing.