It's an early version of the power,audio panel for the motorola XM-501 or 701. From what I've seen it was rarely used but it could be used for audio control and +5v.
I just read in your other post that its from the power supply not a monitor. It's definitely the same board but it looks like there may be some small differences. Do you notice any?
It may not be as cut and dry as I first thought, damn close though.