This is a common failure on the TCON board of this TV series. The voltage reference chip AS15F produces incorrect gamma reference for the panel. It needs to be replaced. This is difficult when you have no SMD hot air rework station. I didn't have one at the time, but I had Chip Quick, a low temperature solder, which stays liquid much longer than normal solder. Alas, the chip has an exposed pad on its belly and that is soldered to the board, too. It won't come off by just heating the pins.
As the chip was already dead, I carfully bent all the pins up to avoid ripping any leads off the board and applied some force on the chip while heating it with the soldering iron. Then, the pad broke off from the chip. No worries. Desoldering it from the board then was an easy task.
Today, I would use my preheating plate and 400°C hot air and it would come off no problem. I am learning :-)
Anyway, got a new chip from ebay for 8€. As I couldn't solder the bottom pad properly (solder paste and hot air required) I put a little heat-conducting block (salvaged from the Sony TCON) on top of the chip. It made contact to the metal cover and should dissipate the heat nicely.
And it is working again:
After this adventure, I decided to get a hot air gun, a preheater plate, and some SMD solder paste :-)
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