Oh dear! NumiQueen is sick!

PowerSupplyOpenThe beloved NumiQueen started to have problems the other day. One minute it was fine, and then the next minute the display faded and then only one digit came on, and dimly. I feared the worst, especially as I have become attached to the large bright display of the IV-13s.

I have other clocks in the same room (which Nixie fan doesn't have an excess of clocks?) but that wasn't the point. It's not about knowing the time: any fool can know the time, it's about knowing the time in style...

I turned the NumiQueen off and on. Many years of using Windows taught me that turning off and on solves most problems, but it didn't solve this one. I turned it off and left it off for an hour, to let any hot components cool off. That also didn't help much. The display would run correctly for a few seconds and then dim out again. 

Clearly this was a sick clock. Jürgen from Nixiekits is in the middle of moving at the moment, and he's not online much to ask questions of, so this is a problem that will have to be solved by yours truly.

TheSweatGotOutAfter doing some investigation, the problem appears to be with the power supply. Looking at the output with a scope, the smoothing is not at all smooth. Sniffing the case of the external power supply confirms the suspicion.

I opened the power supply case and this is what is in there:

 The electrolytic capacitors for the output smoothing have indeed vented. One of them has a vaulted dome on top of it, and the other seems to have just splurged gunk over the board.

The inside of the upper part of the case is also telling. The nasty electrolyte is all over it, and it is very obvious that the capacitors are dead:

The final proof

Extracting the capacitors makes the case totally clear. The power supply is only a couple of months old, but both of the capacitors have failed in the same way. One has bulged the top and the other has vented from the base. Normally this should only happen from older, or over-stressed components.

Or... Ones that are crap.

PoorLittleCaps

I have never heard of the manufacturer "CTC", but it seems significant that both of these capacitors failed in the same way at the same time and after only a few weeks of service. Possibly a bad batch of components. Possibly a bad manufaturer.

But the point remains: If you have a NumiQueen and you have problems with the power supply, it could well be this the cause.

Fixing it

Fixing it was easy: Solder in two new electrolytic capacitors of the same value, but with a lower coefficient of crapness, and we are on the road again, Now it just remains to be seen if there is a further problem in the design of the supply, or if it really was just some sub-standard components.

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#11 Ian 2017-05-02 10:16
I'll post a photo of the offending power supply when I get home. I do remember that it is an "ELPAC", and that the voltage is a slightly weird 7V @ 2A.

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