These Microvitec Monitors were used by many people in the 1980s with home computers like the BBC Micro, Apple II and many others. Different versions of the monitor were produced to cope with different types of input, from Composite Video to RGB. It was designed to be easily modified for these different modes but generally they were supplied with the settings fixed. This monitor was set up for the Apple II computer RGB output. Luckily I have a test signal generator, capable of outputting different modes of RGB output. The fault on this monitor is called "Frame Collapse" and is a well known fault with these models, consisting of a short-circuit capacity which blows a fusible resistor. Replacing both restored normal operation.
Fix - Restore - Reuse