7" TFT monitors, white screen

[torbjorn]

Now I have to repair a dozen of 7" TFT monitors (like automotive rear seat entertainment or truck rear view monitors), probably a chinese OEM brand, mainly manufactured in 2007-2008. So far, it seems impossible to get any technical documentation for them.

The TFT panel is a Hitachi part, TX18D11VM1CAA, and the driver circuitry is built up around a Pixelworks PW113 image processor and an AD9883A ADC.

The by far most common fault (about 70 %) is that they give a completely white screen, neither internal menus nor an input video signal can be displayed. So far, i have checked that all internal voltages (+5V, +3,3V, +1,8V etc) and checked that the clock oscillators are running at reasonable correct frequencies.

Any clues?