I'm with the others - there is something about this slot which differentiates it from the others.
Either it's a mechanical issue with the socket stressing the pins to the extent the tube eventually becomes leaky.... ...or it's to do with the anode driver (the cathodes share the same drive across all tubes) - either the anode resistor has failed in some way (or isn't the correct value) or the opto-coupler is leaky/faulty (but I'm not sure how that would cause premature tube failure), Vceo for a PC817 is 80V, which should be OK, but this one may have failed - they are really cheap, so maybe change it anyway :) Check the values of R11-R16. Have you tried the "faulty" tube in a known-good position in the clock? Are you certain the tube has failed, not the surrounding circuitry cooking slowly over time, then failing, then you turn the clock off to replace the tube so it all cools down and the cycle repeats? Cheers Nick . -- 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/bb0c17cf-e5e2-4109-9515-0d16ace15ce2%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
