One slot on my clock keeps burning out tubes, while the others have been good for years. Thoughts?

[Brando L]

Had a question for you guys, would be curious to see if anyone has seen this too. 

I've had a nixie tube clock for 3+ years and for some reason I've only had to replace the tube in one of the digits, but I've replaced it 2 times and now about to do it again for the third. Since this is starting to look like a pattern and my other tubes have had no issues, I'm thinking it's not the tubes fault. It's the hour position on the clock where X is: HX:MM:SS. When the tube goes, it's like a 1-2 week death; slowly bits of the digits aren't visible, and then less and less until it is digit less. 

What's the best way to diagnose? 

Much Appreciated. 

[Nicholas Stock]

Brando, that sucks. What make and model of clock is it? Can you post a picture?

Nick

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[Jeff Walton]

I recently had the same failure experience with a IN-18 in a Blue Dream.  The digits also faded over a period of a little less than a week until no digits worked.  I posted my experience and the general conclusion was that the way the digits faded was indicative of a failed pin seal.   

Are your tubes all from a particular date code range?  It really doesn't sound like a clock failure due to the equal failure of all digits.  What tubes and clock do you have? 

Jeff 

-------- Original message --------
From: Brando L <bloe...@gmail.com>
Date: 8/15/2016 8:33 PM (GMT-07:00)
To: neonixie-l <neoni...@googlegroups.com>
Subject: [neonixie-l] One slot on my clock keeps burning out tubes, while the others have been good for years. Thoughts?

Had a question for you guys, would be curious to see if anyone has seen this too. 

I've had a nixie tube clock for 3+ years and for some reason I've only had to replace the tube in one of the digits, but I've replaced it 2 times and now about to do it again for the third. Since this is starting to look like a pattern and my other tubes have had no issues, I'm thinking it's not the tubes fault. It's the hour position on the clock where X is: HX:MM:SS. When the tube goes, it's like a 1-2 week death; slowly bits of the digits aren't visible, and then less and less until it is digit less. 

What's the best way to diagnose? 

Much Appreciated. 

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[Jeff Walton]

Brando:  I meant to say that all of the numerals inside of a single IN-18 tube in the H[X]:MM:SS position did the same thing as you described.  My cathodes in the bad tube faded out from the top over a period of about a week or less and the failure began with little warning after operating perfectly since the initial power up of the clock.  I was also running the cathode poisoning prevention.  Have not had an issue with other tubes in other location of the same clock and I got about 2 years out of the first failed tube before replacing with no issues noted on any other tubes.

-----------------

 

I recently had the same failure experience with a IN-18 in a Blue Dream.  The digits also faded over a period of a little less than a week until no digits worked.  I posted my experience and the general conclusion was that the way the digits faded was indicative of a failed pin seal.   

 

Are your tubes all from a particular date code range?  It really doesn't sound like a clock failure due to the equal failure of all digits.  What tubes and clock do you have? 

 

Jeff 

 

 

 

 

 

From: neoni...@googlegroups.com [mailto:neoni...@googlegroups.com] On Behalf Of Brando L
Sent: Monday, August 15, 2016 10:33 PM
To: neonixie-l
Subject: [neonixie-l] One slot on my clock keeps burning out tubes, while the others have been good for years. Thoughts?

 

--

[Brando L]

Thanks for the response Jeff, 

Interesting so that sounds like maybe an issue with the tube itself? So I don't know when the original tube was built that went bad, but all the others that have stayed good on my clock are 75-76. The replacement is from 82 and previous failed tube (2nd failure) is 80. They are IN-14 tubes btw. I purchased like 5 extra tubes when the first one went bad (probably from ebay or something), and all have dates of 80- 82. Maybe it was a bad year? (attached pics just in case, because visuals are always better :) 

[Brando L]

Thanks for the response Nick, check out the pics I posted in the latest comment. Let me know if you want to see a different angle, LED light pollution got in the way a bit too.. 

On Monday, August 15, 2016 at 8:37:52 PM UTC-7, Pramanicin wrote:

Brando, that sucks. What make and model of clock is it? Can you post a picture?

Nick

On Mon, Aug 15, 2016 at 8:33 PM, Brando L <bloe...@gmail.com> wrote:

Had a question for you guys, would be curious to see if anyone has seen this too. 

I've had a nixie tube clock for 3+ years and for some reason I've only had to replace the tube in one of the digits, but I've replaced it 2 times and now about to do it again for the third. Since this is starting to look like a pattern and my other tubes have had no issues, I'm thinking it's not the tubes fault. It's the hour position on the clock where X is: HX:MM:SS. When the tube goes, it's like a 1-2 week death; slowly bits of the digits aren't visible, and then less and less until it is digit less. 

What's the best way to diagnose? 

Much Appreciated. 

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[Nicholas Stock]

To be honest with you Brando, I've never had an IN14 tube die on me...but perhaps I've been lucky. The fact that you've had the same position die on you twice and soon to be a third makes me suspicious of the board. Is there a schematic to it you can post?

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[Brando L]

No problem, attached to this post!

On Tuesday, August 16, 2016 at 3:24:44 PM UTC-7, Pramanicin wrote:

To be honest with you Brando, I've never had an IN14 tube die on me...but perhaps I've been lucky. The fact that you've had the same position die on you twice and soon to be a third makes me suspicious of the board. Is there a schematic to it you can post?

On Tue, Aug 16, 2016 at 1:07 PM, Brando L <bloe...@gmail.com> wrote:

Thanks for the response Nick, check out the pics I posted in the latest comment. Let me know if you want to see a different angle, LED light pollution got in the way a bit too.. 

On Monday, August 15, 2016 at 8:37:52 PM UTC-7, Pramanicin wrote:

Brando, that sucks. What make and model of clock is it? Can you post a picture?

Nick

On Mon, Aug 15, 2016 at 8:33 PM, Brando L <bloe...@gmail.com> wrote:

Had a question for you guys, would be curious to see if anyone has seen this too. 

I've had a nixie tube clock for 3+ years and for some reason I've only had to replace the tube in one of the digits, but I've replaced it 2 times and now about to do it again for the third. Since this is starting to look like a pattern and my other tubes have had no issues, I'm thinking it's not the tubes fault. It's the hour position on the clock where X is: HX:MM:SS. When the tube goes, it's like a 1-2 week death; slowly bits of the digits aren't visible, and then less and less until it is digit less. 

What's the best way to diagnose? 

Much Appreciated. 

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[gregebert]

Since it's multiplexed, it might be worth comparing the 'on' time of each tube (I'm guessing it's H2 on the schematic ?). You'll need a scope. Maybe there is a quirk in the controller firmware that leaves this particular tube on longer ?? There's also a slight difference in the circuit around tubes H2, H3, and H4 though nothing pops out as a possible culprit.

Any chance there's a source of heat next to tube H2 ?

Only other thing I can think of is if the particular socket puts more stress on this tube.

[Nicholas Stock]

Could the photocoupler at HC2 be the culprit at all? When you change the tubes, is the brightness of the IN14 at that position the same as the rest?

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[Jeff Walton]

When all of the cathodes in a single tube lose large patches of coverage in a short period of time, it still seems that it would be a failure of the gas mixture.  Over driving the cathodes for a period of time would cause an eventual loss of brightness but it should cause variations among the cathodes and not a sudden loss of coverage on all cathodes.  

GregEbert suggested to look at the socket to make sure that pins aren't stressed, which seems to match your description of how the tube failed...  Three failures in the same socket does seem to be more than coincidence and it would be a good question to determine whether mechanical or electrical.   You should follow up with the group regarding future failures and/or findings as it is interesting. 

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[chuck richards]

Sounds like a multiplexing issue to me.
I am guessing that this particular tube in question
is getting cooked for quite a bit longer than the others.

Chuck

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[Nick]

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

.

[Terry S]

I think that it's a mechanical issue. Any electrical issue that over-drove the cathodes would be visually apparent during operation -- especially at levels that could destroy cathodes in a matter of days or weeks.

Terry

[A.J. Franzman]

Either bad luck and coincidence getting three bad tubes, or THIS: