What to check

Usually a Monitor on power up will turn from Dark to Light grey with no video input, measure for about 12v between the Red & Black wires going to the monitor, in the bottom right corner, there is a contrast knob sticking down, the tracks on this pcb can fracture if the nut is too tight.

These Sony monitors have HIGH voltages in them, if they get wet or damp, arcing can occur on the back which you may hear.

Corrective Action

These monitor leads have different size plugs.

Replace 900-VM PCB

Replace 900-BRT PCB

Replace the Monitor, 3 types.

Additional notes

These monitors have different size sockets for the leads.

VIS4000E with fuse, large plugs.

VIS4000E without fuse, small plugs.

VIS4x4E small plugs.