I'm trying to fix this "ITV digital" UK DVB-T receiver.
Symptom is no audio and dreadful video quality (both scart and RF). Video amplitude is very low and noisy, my TV barely manages to sync and display it, though it is visible enough to allow one to see that the digital decoding is ok. One can just about see enough to navigate the menus, which all seem to work.
I suspected a power problem on the analog buffering, however all caps ESR ok and rails (as far as I can guess what they should be) seem ok. The outputs are buffered with discrete transistors (emitter followers) which seem to be working ok but receiving a dreadful input.
This box uses a Sony CXA2092Q chip to generate the video, so it would be a natural place to continue debug. (I guess it sources the audio too.) Maybe it's missing a power supply? However I've been unable to find any datasheet for this chip with Google (only the usual Chinese sites selling parts...)
It's a multi-layer PCB (with most signals on internal planes) and hence a nightmare to trace.
Does anyone out there have info either on the Sony CXA2092Q chip (just a pinout would be a huge help) or maybe schematics for the Nokia DVB 9850T box? Alternatively, pointers to schematics for any other device using the CXA2092Q which might reveal a typical usage, voltages etc? I'd guess this chip is used in a variety of MPEG-2 video devices (satellite, DVB, cable etc).
Thanks for your help.
Mike.