I wonder if anyone can offer some sanity saving tips on this one. I've got a DVD Player which, for some reason, has suddenly decided to output only in black&white.
My first thought was that someone had been fiddling with the remote and stuck it in the wrong mode or something but it's not in NTSC or SVHS or any of those alien modes (alien to my current setup anyway). The effect seen on the screen is a black&white picture with some visible patterning and some expanding rings. The effect is similar to that seen when you try to view an SVHS output on a standard video screen. This effect is seen from the SCART output as well as the composite video output. There is also a button on the controller called "picture mode" which takes you through a few useless gimmicks to add different effects to the picture. One of the picture modes is actually "black&white", and if I select this mode the picture stays in the black&white mode, but the previously visible patterning dissapears leaving a crystal clear, b&w picture. This would seem to suggest a problem with the colour processing somewhere.
I've stuck my scope probe directly on the composite output port and played back a home-made ColourBar DVD. Strangely, the video output looks completely normal - I've got colour burst, I've got the familiar bands of colour information that you would expect to see when displaying colour bars, and all the amplitudes and periods seem to be correct. With all that in mind, I'd have expected to have seen some colour on the screen, even if that colour information was wrong in some way
My next suspect was the colour burst. I decided that if the colour burst frequency was off, perhaps the television wouldn't display the colour properly anymore. I've managed to crank my scope down so that I can view the colour burst properly. 10 cycles at 4.43Mhz. So even the colour burst is right!!! I can't say whether the phase of the colour burst is correct, and I would think it'd be incredibly difficult to confirm that.
Any bright ideas? If I had an older television I'd consider bypassing the colour killer to see if it brought colour to the screen, but that's not such an easy trick these days.
Brian