We obtained a mysterious box of 1960s electronics. I reverse-engineered it and with much effort, we got it running. It turns out to be a test unit for testing NASA's Up-Data Link, a system from the Apollo moon landing to control the spacecraft from the ground. Let's take a look inside... 1/n
@kenshirriff Loving the Nixie tubes!
Did you have to replace any?
@thomasadam @RolfBly Although the digits look like Nixie tubes, they are a different technology: edge-lit lightguides, driven by ten incandescent bulbs for each digit. We had to replace a few bulbs.
https://oldbytes.space/@kenshirriff/114892205352274039 
Attached: 1 image
This box has thirteen orange digits at the top, which look like Nixie tubes. But they are a different technology called edge-lit lightguide display. Each digit has ten plastic sheets and ten lightbulbs. Each sheet has dots etched in the shape of a number. Lighting a sheet lights up that number.
Ken Shirriff
Thomas Adam