On the Badcaps.net TV repair forum we've been noticing an interesting trend.
Since about 2012 large numbers of chips on T-con boards (the part which controls the LCD panel in an LCD TV) are failing. In every case the chips are AS15 or AS19 from the same manufacturer, full part number EC5575, datasheet
here.) Replacing the IC solves the problem in virtually every case (symptoms being distorted colours, solarised picture, poor contrast or overbright image.)
The IC is essentially a 15 channel voltage buffer (internally implemented as a unity gain op-amp.) When working, each output follows a nice smooth curve. When failed, typically 3 or more points of the curve will become distorted; but usually at least a few of the points still work. Of note, the input sources are high impedance (from a resistive ladder), and they typically get pulled the same way, so the REF input matches the output. Removing the IC makes the voltages return to normal.
When the IC is failed it runs about 20C hotter than normal. Normal operating temperature is about 35C.
The failure is typically described as sudden; one moment the TV is working, and the next, the image is bad. Sometimes, as the IC warms up, the fault will get worse. The ICs have been found to last between 3 and 6 years before failure, although hours of usage are unknown because they don't operate with the TV off. They've been found on boards from Chungwha PT, AU Optronics, Samsung, and Chi-Mei Optoelectronics... so it's not just one manufacturer screwing up the design.
Any semiconductor guys here might know what's going on? My personal guess is some kind of bias circuit for the input is failing, but it's failing on random channels, and not all at the same time, which is odd. Not sure why the failure would be so random, rather than for example only affecting the middle most channels (with the highest power dissipation.)