z568m tubes starting to fail

[christopher helps]

Hello,

I have had a six digit nixie clock running on and off for a number of years but today switching it on after being boxed up for a year it is showing signs that some tubes are fading!!?

Is this something that can be repaired-by anti poisoning?..is this the first sign that they are on their way out.

It seems odd that it was fine before boxing them up then suddenly three of them have some digits with dark areas...any advice would be very grateful

[Jeff Walton]

A tube that has sat dormant for a long period can exhibit these issues.  The cathodes can pick up surface contamination which will likely clear up if you run them for a day or two.  It's not exactly the same as operating cathode poisoning but shows similarly.  This is very typical when you get an old nixie.  Regular operating keeps the cathode "cleaned". 

Jeff

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[christopher helps]

Thanks, i will keep fingers crossed.

I never realised keeping a tube unused would be bad for it... but i can see first hand this has happened

[gregebert]

Are the tubes fading uniformly, or just in specific locations on the cathode surface ? If it's the entire cathode , I would check the anode supply voltage and also the current-draw on good vs bad tubes

[christopher helps]

Its failing on certain parts of certain numbers. mainly 7,8,9 .i will post a pick later

[christopher helps]

I have realised that i must have plugged the tubes into different holders so the hours went into the minutes etc....does it matter if an hour nixie is poisoned as it only needs to show three digits?..pic attached

[Paul Andrews]

So the hour tube is poisoned on the digits that it doesn't normally display? That could explain it as they would have sat unused for a long time, and I think that running those digits at a higher current for a while would clear them up.

But to answer your question: No it doesn't matter - i.e. it won't hurt the tube.

[Terry Kennedy]

On Tuesday, May 15, 2018 at 3:42:10 PM UTC-4, christopher helps wrote:

I have realised that i must have plugged the tubes into different holders so the hours went into the minutes etc....does it matter if an hour nixie is poisoned as it only needs to show three digits?..pic attached

Is that the Nixie version of the clockspider I see lurking behind? 

[christopher helps]

I must trim those spiders legs!

Thanks for the advice,i think ill just have to live with poisoned hour digits.