PS/2 power supply connection (by 2 users)

You seem to have an oddball monitor if what you describe is correct.
The power supply to a monitor[Display Screen is that what you mean?] is either direct to main power- in which case the power cord is either built in with a power plug for wall socket,
or has a socket on the back for a separate main power cord.

Or is powered from a low voltage converter that delivers low volts usually via a coaxial plug like this illustration

PS2 connection does dot come into the equation as far as I know unless you have got hold of something unusual.
Tell you what take a shot of the back of the monitor and lets have a look see mean while here's is a shot of a typical low voltage power supply available anywhere.