“Main B Bus Undervolt!”—The Obscure Component that Signaled Apollo 13's Troubles

The “Circuit Utilization Panel”, nestled in the Apollo command module’s equipment bay, was responsible for monitoring the electrical power systems of the spacecraft. It was the first to detect the cascade of equipment failures that occurred after the explosion of a liquid oxygen tank in the service module en route to the Moon, leading to the famous transmission:

Hey, Houston we’ve had a problem.
We have a main bus B undervolt.

Can this original unit, rescued by a collector, reproduce the fault detection that began the drama of Apollo 13?