Hugh Prescott wrote:
Just a note on Nixie driver chips. Experiences from the 60's

Most I have seen are working right at their breakdown voltage when the
element is off.

Most are open collector pull down outputs.

If you change chips install sockets if they are already present.

Details with chip numbers would help greatly. Pictures even better.

I don't recall ever having a Nixie fail, was always the driver.

Will help as much as I can online

Hugh

Alright... nixies aside for a moment... First thing I noticed is
that the display changes when you move some of the thumb switches.
(This unit has s thumb roller switch for each nixie so you can set each
digit on the display. Then you press "Set" to send the selected numbers
to the display.) The display should only change when the set button
is pressed. I verified the output of one of the counter chips
(SN74192N) was changing without pressing the set button with my
logic probe. Then I verified that the LOAD line was not changing
when the rollers were moved. This happens for three of the five
counters. I think I may just replace them all. Your thoughts?