LG LCD TV - extremely bright picture when TV warms up

[Delta]

A TV in a local boozer is on the blink.  It's a 42" LG, not the newest.  It turns on OK, and displays a perfect picture, but after 10-15 minutes the picture "whites out".  I say "whites out", but is more like the brightness has been turned up to an extreme level.  You can still see the picture, it's just really really bright.

What could be causing this?  Is it (economically) repairable?  (I'm not sure if a replacement T-CON board is available)

Thanks!

[Cyberdragon]

Could be a bad connection either to or on the backlight board causing it to loose the PWM brightness signal and default to full. Check the cable and solder joints (poke them with something non-conductive when on). Is it an LED backlight or a CCFL tube type?

[Rasz]

you cant 'white out' lcd wityh a backlight

its a glass/tcon problem

[BMack]

I think you mean solarized. If that is the case I'd say it's either the panel or the T-con, it could be the power supply. First, flex the tv a little bit, if it fixes the picture it's a bad panel. If not check the voltage going to the T-con, is it stable? Check with the T-con plugged in and without it plugged in. I expect you'll be replacing the T-con. You can monitor it for hot chips and check components but check for the part cost first, normally we replace T-cons because it's not worth the hassle to fix it on the component level.

[amyk]

That sounds like a gamma buffer failure. Do they happen to be AS15/AS19 in this TV?

From https://www.eevblog.com/forum/chat/why-might-these-ics-be-failing/

Replacing the IC solves the problem in virtually every case (symptoms being distorted colours, solarised picture, poor contrast or overbright image.)