Today: with a scalpel.
Our three-phase power supply has been a bit uppity recently. By uppity I
mean: beeping insistently, leaving the outputs at 110V and ignoring the
stop button. This behaviour is not appreciated.
Opening it up revealed that the front-panel is connected to the power
modules via a fibre ring. This is nice design because it prevents
interference and isolates the high-voltage bits from the control electronics.
Unfortunately the packets were only making it two-thirds of the way around the
ring where they encountered a rather suspicious kink. It had probably
been there since it was manufactured, but now with age a border-line component
had become a faulty component.
Fortunately there was enough slack in the fibre at that point that the
kink could be cut off and the new end fed back into the receiver.
Unfortunately I didn’t make a particularly clean cut and there are still
intermittent faults. It will do until the new fibre arrives.