Im not sure Im understanding your problem. Are you saying that
the 12v pin-in from the PSU connector on the reverse of the
mobo is missing? Or that the cable from the PSU to the
PSU connector is missing?
You could run a new cable from the 12v pinout on the PSU
into the mobo ( the hardware specs are in the manuals
that came with the A1200 if I recall clearly ). Or you could
get an A500 powersupply.
The other thing to do is buy a ZIV or a Mediator busboard. If I recall
correctly both of them have power re-routed through them and
power the entire motherboard and themselves. That of course
is best driven by an Elbox or Power tower.
