that thing in the bottom pic with the cooling tines on it is a power supply but for a pcb, not the monitor.
that big square block might be an ioslation transformer but its hard to say with all the wires piled all around it. if it only has the plugs you describe coming off it, its not an an iso transformer, but just part of the power supply on the bottom pic.
the monitor has to be plugged into the isolation transformer, usually with a small rectangular 2 wire plug and should be coming directly off the isolation transformer.
the only way to test it is to have a proper working power supply, isolation transformer and wiring harness to connect the pcb and the video up to the monitor.
all that power stuff is an older linear power supply that is most likely for a specific game.
easier to find a local friend with a jamma game that has a wg monitor in it and hook it up. the WG monitors like k4900, k4600 and k7000 use the same video hookup.