Are you measuring the anode signal at the anode-pin of the tube, or at the driver ? Always possible something went awry on the board, etc (failed anode resistor, tin-whisker shorting between traces).
Is the anode supply adjustable ? Try boosting it a bit to see if the tubes are aging and need more voltage to ionize. Seems unlikely, though, because I would expect 1, not both, tubes on the driver to fail at the same time. Are the tubes socketed ? If so, number them, remove all of them, then use a good tube to check each socket one-by-one. It will provide another clue. I was thinking that one or both of the tubes that doesn't illuminate has an internal short; I've seen this with IN-1's though it was always cathode-to-cathode, which resulted in 2 numerals turning-on at the same time. If the tubes are soldered, I would try disconnecting the anodes of both suspect tubes, then reconnecting them individually to see if one of them has an internal short. -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to neonixie-l+unsubscr...@googlegroups.com. To post to this group, send an email to neonixie-l@googlegroups.com. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/576f4e55-3879-4074-9bb4-4f677d6b327e%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
