second tube quit working

[sonicwarhawk]

my unit ran with no issues for over a year, but the middle tube just stopped working. led lights up. but nothing from the tube. i need to know what to check to troubleshoot. thanks tony!

[sonicwarhawk]

also i noticed i mislabeled the subject, should be third. its late here...

[Tony]

Was there any sign of problems or did it just not work one day?. First thing is the anode voltage, the pin with white insulation. You should see 140-170v here depending on your meter.

[sonicwarhawk]

i work away from home for 14 days at a time so i unplugged it before i left, when i came home and plugged it back in it just refused to light. what am i checking the voltage across?

[Tony]

Measure between the anode pin and ground, the USB connector housing is a useful reference point.

[sonicwarhawk]

not seeing that kind of voltage on any of them. looks like between 40vdc is what im getting on all of them. the one thats out is showing slightly higher at 50vdc. sorry for the lapse.

[Tony]

The reading can depend on the meter as it's being switched at high speed. If the working tubes are reading lower than the faulty one I'd say it's the nixie itself that's the problem - it's being supplied with HV but as it's not conducting anything the reading is higher.

[sonicwarhawk]

Thanks tony, i happened to pick up 3 spares a wile back for just this scenario. ill swap em and let you know what happens

[sonicwarhawk]

swapped in a new one and it worked like a boss. guess the tube just gave up the ghost