Hi
I have a Megger BM222 insulation tester with a fault. It works perfectly on all switch selected functions except for the 1000V insulation test.
On the 500V test, a relay can be heard clicking then the displayed voltage/resistance ramps up.
On the 1000V test, the relay is not heard and no voltage/resistance is displayed.
So either the relay is not being driven to switch, or the relay is not responding to driver signals. The circuit board is far more complex than you might expect. Fault finding could be done, but it would be a lot easier if I had a circuit diagram.