First 4K set on Badcaps...? LG 42UB820V

[Alastair E]

Spotted this 4K set on the web going cheap private-sale so bought it,--No known faults, just no longer needed. Made in Sept 2014 and is a current model....

There's nothing actually formally Wrong with the set, but its infuriating irritating POS active-backlight.

Up and down it goes ad-nausium. It even switches off the backlight during periods between scenes, giving an unnatural dead effect....

Ive gone into all the various settings, turned on and turned off all the active contrast, backlight, colour enhancement 'Eco power' (bollox) features, but the damned thing still varies its backlight with picture-content, and switches off between scenes--VERY obvious when there's a Scope film or some other letter-box representation such as adverts on screen.

Plus--The Black-Level is Horrible!

Its a Grey-Level, and more importantly, and irritatingly a Varying Grey Level.

There was a scene in a film where it was night. Person facing away from camera with dark hair, turns his head side on--the whole screen lights up grey!

If I could get the BL to stay put, I could set the picture up for a (For an LCD POS) reasonable, but when varying--its maddeningly impossible...

Apart from cracking this 4 month old 4K set open--Any ideas on how to disable backlight variation with picture-content??

[stj]

Re: First 4K set on Badcaps...? LG 42UB820V

did you check for a firmware update yet?

[Alastair E]

Re: First 4K set on Badcaps...? LG 42UB820V

Well--seeing it was only made in September--err, no I didnt!

I cant see that they would have one for such a young model yet, but will check....

I dont like just 'Updating Firmware' for the sake of it, often doing so can cause troubles where there wasn't any!
As the issue Isnt a fault--I cant see that LG would have altered anything with the F/W for the BL....

As an observation--Not that it has That much relevence seeing its nowhere near the same model, The 42LE4500 that I just repaired--by potching the BL Controller board out of circuit has in fact a better black-level than this set, as at least with a fixed backlight, its possible to set it up and retain some kind of decent black-level, and no irritating brightness variations....

[tom66]

Re: First 4K set on Badcaps...? LG 42UB820V

Contrast ratio will be even poorer for a 4K LCD set, because the pixels are smaller the leakage area to active pixel ratio is much higher. This also means they need a lot more backlight power (at least 50-100% more) Nothing you can do for improving that. 4K sets are made to shift units on specs but not on picture quality.

Have you tried some service menu access? Samsung sets had this irritating fault (in fact most of them still do, except their higher end models.) You could turn it off in the service menu with the exception of the screen blanking out during full black scenes. (The solution to that was to turn the SUB BRT in ADC CAL up one notch so the black level rises ever so slightly above nominal, preventing the TV from shutting off the backlight.)