Hi guys

As you may now, I have a quite old MV Junior (1987), which I brought back to live, from some defective hardware (masteboard, memory board).

The machine is mostly running good and does produce accurate parts...
But sometimes is does do me some nasty stuff.. Maybe you have an idea on where to look:

The biggest problem:

Sometimes (lets say once a month) when the machine is running, the control suddenly shuts down completly (like you press the red button, to shut down the control (not the e-stop)).
Its like the machine does power off.. Screen is black. The are no blown fuses and the cabinet is still powered.

A push to on the green button, restarts the machine as usual. No problems other than dealing with the afthermath of this sudden powerloss.

This as very annoying, as I never know when this will happen. Mostly I have seen it though, on the following occasions:

1. During a tool change (when the arm motor is powered)
2. In Rapid Moves at 100% rapid speed

It does seem like the is something tripping, because of overload, which will cause the machine to power down. But what can that be?
Could it be somthing from the power off switch itself? Like a faulty contact? Can anydoby explain me how the power on circuit is done? With a self holding relay?
Could it be issues from our power outlet? Its 32A 400V and then going into the cabinet, then to the external transformer.

I find it kinda strange, that it happens on two totally unconnected occasions..

Thanks for any advice