PC-186 - Colour Monitor Sync Selector:

The RM Nimbus can drive a monitor with either a Positive seperate Sync or a Negative mixed Sync signal. The standard Nimbus Monitor is Positive Sync.

Early units had a selector switch accessible outside the Nimbus case:

Later versions removed the switch and used jumpers instead:

Positive Sync.	Negative Sync.

!!! DO NOT CROSS THE JUMPERS VERTICALLY !!!