rejuvenation of neon bulbs and nixie tubes

[FrodeM]

It is reasonably well known that there's a fair amount of things that can cause the striking and discharge voltage of neon bulbs/nixie tubes to rise, including storage. It is also generally agreed that this can be remediated at least to some degree by the process of giving the bulb an extended period of burn-in, typically at a little over its maximum rated current. However, I have not found any decisive number about just how far you can pull the operating voltage back down doing this.

Now, I have two B5991 nixie-tubes that have risen some 30-40V over their typical values, and they are giving me a hard time lighting fully, even at 15% above their maximum current-rating (above that it tends to illuminate the lead going to the digit and not the digit itself). Would these be possible to recover, or are they completely done for?

[factory]

Are they working in the machine they are fitted in?
If they are I would advise to avoid disturbing them, as these Burroughs tubes are often very tight in the socket and damage can happen from removing them, usually resulting in a crack starting from one of the pins.

David

[FrodeM]

Are they working in the machine they are fitted in?
If they are I would advise to avoid disturbing them, as these Burroughs tubes are often very tight in the socket and damage can happen from removing them, usually resulting in a crack starting from one of the pins.

David

Most digits on these two bulbs only light up about 20-30% of the surface when used in the original machine they were used with, with the original anode-resistor. For instance, like the upper curve of the nr 3, or the foot of the nr 2. That being said, I got these with some spare-part modules so they have probably not actually been in active use for a good while. With a lower resistor value and the current mentioned I can make about 50-70% of the surface of most digits light.

The part that lights is normal brightness I would say, but the rest of the digit stays dark. 5 other nixie tubes from the lot work just fine with the original current limiting. When measuring a good tube, they have a discharge voltage drop of around 135-140V, not 165-175V as the flaky ones.