Keithley 164 Nixie Tube Multimeter Repair
The microscope: http://bit.ly/2vLB0Sl
The patreon :) https://www.patreon.com/marcoreps
We have briefly looked at this ancient DMM before, but delayed the repair for a while. Now the time is right! We are diagnosing a problem with the Nixie supply voltage and replicate 2 unobtainium ICs with modern components. The 960 driver aka Fairchild 996079 aka 9960 is a Nixie tube driver, that interfaces with 3.6V logic and takes an inverted BCD input. I'll imitate its behavior with a 74HC42 BCD decoder and discrete MOSFETs.
Equally the MC867P is replaced by a 74HC75 and a few pull-up resistors.
What now? I don't even need it as a DMM?