Fuzzy digits, fried K155ID1?

[StoopKid]

I packed up my half finished clock quite some time ago and I just decided to try playing with it again. However I am immediately running into this problem that I had before. Something is going sour with these K155ID1 chips and making the 3 and the 4 just go fuzzy and weird. I had a bunch of spare chips but now as I replace them they just keep doing it so now I am afraid that I am burning them as I go whereas before it would just be occasional. I don't want to try all of my spares if I am just killing them.

I can't find anything on google about this. I don't really know what I could be doing to cause this. I am pretty sure that it is an issue with the chips because I have always had it happen occasionally even when I was just breadboarding and stuff. And the problem would always follow the particular chip, if I moved it the problem would follow. If I replaced it, it would go away for some time.

[gregebert]

I cant tell from the picture if the 3 & 4 digits are illuminated at the same time, or if it's something else such as leakage. You mention problems with '3' and '4', but are all other digits OK ?

The driver you use has a Vceo rating around 50 volts, which is susceptible to leakage if your anode voltage is significantly higher than the sustaining voltage of the tube. Whether or not this is the actual problem will require some debugging.

Is it possible to modify your software so the digits are fully extinguished for a few milliseconds before the next digit is energized ? This should be pretty easy to do if your display is multiplexed. That will provide a few clues about the problem. Also, as you know, nixie tubes have their cathodes "stacked", and the order is not necessarily numerical. I'm willing to guess the '3' cathode is closest to the anode, and the '4' is right behind the 3. Burroughs 5031/5092/6091 tubes are constructed that way (Oh, there I go again about Burroughs tubes.....)

[Paul Parry]

I've seen this before, but only on a multiplexed design. I doubt very much it is your K155ID1 chips, I had a duff Nixie tube that had failed internally which then caused all the others to look this way - it was a tiny miniature Rodan tube and a pig to find because I didn't expect a tube to fail this way and they were all soldered onto the PCB. Just check with a meter on Ohms that there is no suspicious low resistance between your cathodes on your multiplex bus.

 

Cheers,

Paul

 

 

[Niek]

Could you post the schematics of your clock? That way, it'll be a lot easier to see if there's something wrong with the design.

[Terry Kennedy]

On Monday, August 4, 2014 10:38:39 PM UTC-4, StoopKid wrote:

I can't find anything on google about this. I don't really know what I could be doing to cause this. I am pretty sure that it is an issue with the chips because I have always had it happen occasionally even when I was just breadboarding and stuff. And the problem would always follow the particular chip, if I moved it the problem would follow. If I replaced it, it would go away for some time.

There have been bad batches of those drivers in the past. Jonas from TubeHobby had to replace a large number of them in his NCV2.1 clocks because they had the "0" and "2" digits ghosting. So it may not be your design, it could actually be a problem with the 155's. Are all the ones you tried from similar date codes and in the same packaging type (plastic / ceramic)?

[Nicholas Stock]

I've certainly had a bad K155ID1 or two...but I've also seen a failed MPSA42 do the same thing in a clock, but only on one tube...any chance you have a transistor failure somewhere?

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[Tidak Ada]

Always the same tube? Smells to tube failure...

 

eric

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From: neoni...@googlegroups.com [mailto:neoni...@googlegroups.com] On Behalf Of Nicholas Stock
Sent: woensdag 6 augustus 2014 4:47
To: neoni...@googlegroups.com
Subject: Re: [neonixie-l] Re: Fuzzy digits, fried K155ID1?

To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/CAOX%2BRHKRX-J516ob4DjixfmS281BEfbX_uy3NGYkmwqAqjEohQ%40mail.gmail.com.