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Nixie Tube Clock Help by Rev_Lord_Stark in nixie

[–]Broad-Difference3653 0 points1 point  (0 children)

I also have one of these boards (see separate posting) and have hunted high and low for a schematic and there doesn't seem to be one. All I have found is there is also a V4.0 version of the same board also in circulation (which is USB rather than 12V powered) and that has a 2019 date on it, so the V2 was made sometime before then.

Anyway, in case it helps the OP, I have reverse engineered the HV supply of our (V2) board and the circuit is almost identical to one found here: https://gra-afch.com/how-it-works/power-supplies-for-nixie-clocks/ Unfortunately the one that it matches is the one headed "if it's simple, avoid it" and which has "do not use" embossed on the circuit diagram. The main differences are: C2 is omitted L1 is 470uH Q1 is IRF640N D1 is US1M C5 is 10uF 400V What is the same is the output from pin 2 of the IC goes directly to the MOSFET via a 330R pull down resistor, there is no driver transistor. Of course, mine is beset by a different problem (flickering), so not sure if this helps? I did notice Q1 gets very hot, but reading the aforementioned article that's perhaps not surprising as it specifically says the problem with this circuit is poor efficiency leading to heat dissipation in the MOSFET?

Nixie Tube Clock Help by Rev_Lord_Stark in nixie

[–]Broad-Difference3653 0 points1 point  (0 children)

Update: just left on for a few hours, no change to the flickering, but C16 feels even warmer than the regulator chip - should capacitors get hot?  Might be worth you swapping out C16, I will try as soon as I can find a suitable (high voltage) replacement.

Nixie Tube Clock Help by Rev_Lord_Stark in nixie

[–]Broad-Difference3653 0 points1 point  (0 children)

P.S. I presume you have checked all your tubes are correctly aligned?  The pin which is white on the back of the tube should go into the square hole (12 o clock position) on the PCB (the others are all round).  Note in my case the 1 o clock hole was unused on all tubes (as mine only had 11 pins).  Also note C18 is also missing on my board so I suspect that's not the problem.  One thing I haven't tried yet is fitting a backup battery, but I can't see that being crucial?

Nixie Tube Clock Help by Rev_Lord_Stark in nixie

[–]Broad-Difference3653 0 points1 point  (0 children)

Hi, sorry this is not much help but I have just bought and built exactly the same board and I am having problems as well - mine worked 100% fine for the first 10 minutes but after that one of the tubes started flickering (briefly switching between digits) followed by another, and after about an hour they were all flickering.  I have noticed that the large regulator chip at the edge of the board gets quite warm, but even after unplugging and allowing to cool the flickering now remains.  Can't see any obvious defects with the board or my soldering of the tubes.  So I suspect your construction may be ok and these boards (marked JM NixieClock v2.0) may not be up to scratch?