Adapting digital RGBI monitor to accept analog RGB

[tony duell]

> I am in possession of two Magnavox (North American Philips) CM8562
> monitors. Out of the box they handle composite and digital RGBI (CGA)
> input. What I'd like to do is get one to handle analog RGB (like arcade
> boards, Amiga, Atari ST, and Apple IIGS put out). I wouldn't think this was
> possible, but I seem to have a certain memory that I saw mention of doing

My guess is that it is possible. The CRT is an analogue device. There must
be circuitry in the monitor that accepts the 4 digital signals and turns them
into 3 analogue signals to feed to the video amplifiers. So you should be
able to feed in a suitable analogue signal after said conversion stage.

Last time I was inside a similar Philips monitor, the main PCB was designed
for all possible versions, but only the necessary components were fitted. If
you can get the service manual for the version you want (with analogue
inputs) compare the PCB layout with the version you have to find out what is
missing.

When I had to do something like this, the hardest part was finding the
right switches and connectors that would fit on the PCB and line up 
with the holes in the case.

-tony