Philips PM2494 digital panel meter (1972)

The PM2494 is a digital panel meter with a 3.5 digit display using three JRC B-5755 nixie tubes (made in Japan) and a neon lamp for the leading “1”. It uses TTL (Transistor-transistor logic) for the digital circuitry. Between the 7490 counters and 7441 decoders there are 7475 latches, so it should give a nice continuous readout when used. I carefully removed the front panel and slid out the two boards. The nixies, counters, decoders and control circuits live on one board. The power supply and analogue circuits are on the other board. The boards are connected by a ribbon cable, carrying power and a few signals. The ribbon cable is broken, though, so this unit will not work (yet).