Philips 37PFL5603D - washed-out colors - AS15F chip defect - TCON board T370HW02 V402

Some repairs are becoming a routine like removing the appendix from the bowel. This TV showed all signs of a defect gamma chip on the TCON board. In most cases a solarization effect is produced by a broken gamma chip. Here though, the colors were almost completely gone (the moiree pattern does not exist in reality):

This device is from the golden age of LCD TVs (around 2008/2009). It is built like a tank. With its 25kg it trumps modern 46 inch TVs. The capacitors are all top quality and showed no signs of aging whatsoever. All wires are protected by sleeves, the boards are mounted on an extra frame. In modern TVs, they are screwed directly to the backplane of the panel.

Those HDMI ports will never break off:

You don't see this type of LVDS cable anymore. Solid plugs, massive sleeve and shielding. Not this cheap arse flat wire crap like today.

Removing the TCON was a bit tedious because the frame was in the way and I needed to lift it with one hand while loosing the screws with an extra long screwdriver with the other hand, pointing through the holes.

The infamous AUO type TCON board appeared. They are known for AS15-F gamma chip defects. The Samsung LE37B650 I fixed a couple of months ago had one of those, too. The chip is hidden under a heat conducting block, which needed to be replaced afterwards, because some material got ripped out when I pulled it off. To conduct heat properly, its surface needs to be smooth.

How can you measure the AS15 gamma chip? You locate the gamma voltage test points on the board and they should show a continuous stepwise increase / decrease of voltages from VGMA1 to VGMA21. Any test point with no voltage (a few millivolts) or a large gap is a sign of a broken AS15. In this TV, I tested VGMA1 to 5 and got nothing. I didn't bother testing the other voltages, as this was a clear case.

With the help of my pre-heater plate at 170°C and the hot air gun at 420°C the chip came off like a charm. On this board, it is not soldered to the ground plane for heat dissipation.

I screwed up the first replacement and the picture was even worse. Either the chip was dead on arrival or I broke it while trying to solder it with paste. The next one I soldered with the iron and plenty of Chip Quick flux (my favorite!).

A new heat conducting block attached to the chip and the board was good to go. On the picture you can still see the protective plastic film, which I almost forgot to peel off :-o

The colors came back alive:

Hallo Frau Johansson!

So, this was a quick and easy fix for as little as 10€ (including the failed first attempt). Not bad at all.