I didn't receive these devices with power supplies, so the first step was determining their requirements.

Opening the wood and metal cases was accomplished with screwdrivers. The manufacture dates marked on the boards are circa 1997. 20 years - not a bad run, I suppose.

The voltage regulators on the boards are 78MxxCT, which take any Vin under 35V. Pretty much any laptop power supply with the same polarity in the barrel jack works nicely - mine are from a pair of Fujitsu.

Power on to the boards! The display lights up brightly, and shows "NO SIG NAL". Charming. The MCU is rather dim, but blinks a light once every second on the reverse next to an RJ11 jack, and has a steady green light on the front.