Thank you! I took it apart and figured out which line
is the video,
but as I posted elsewhere, I need to find a 5V power supply.
I an't beelive the PSU for a singel-board machine of that vintage is
goign to be very complicated. Can you not repari the existing PSU.
Ah... I've gound it. I've got a Challenger 1P manual in front of me. The
PSU scheamtic (on shet 12 of 13 of the system schematics) is clearly
incorrect. It shows a centre-tapped transformer with the tap earthed
feeding a bridge rectifier with the -ve side of the output also earthed.
This effectively shorts out the transfomer with the diodes, which would
blw eitherh te mians fuse or the diodes.
I am goign to assuem the earth on the tap is an error, and that the
transformer secodnary is not, in fact, tapped. If the PSU layout is to be
lelieved, you should get about 8V across C1, this feeds a 3-termain
regualtor off the PCBm the outout of that provides 5V to the rst of the
machien via fuse F1.
So, it is very simple, it should be trivial to fix.
If yoyrs is actualyl a Superboard 2, then the PSU is external (the PSU
locations o nthe PCB were not populated, I guess), it needs 5V at 3A. If
you have the extisting PSU I can't believe it's complicated.
-tony