Have you checked the soldering on the connectors for the tube sockets? Sounds like you may have a short either on the minute socket or daughter board you used for the minutes. The 5V rail is functioning OK as the LED's light as you say, if the HV is only reading 12 to 13V then your assessment of the HV generator going kaput is probably correct. If you've already changed the IRFD220, then check the other parts in the HV circuit....are the Caps C3 and C4 the correct way round (an easy mistake, I've done that one before..;-)..
Have you discussed with Pete? He's the best resource for this obviously and very helpful....hope you get it sorted, they're great little clocks. Cheers, Nick On Thu, Jan 15, 2015 at 7:33 PM, barnbwt <[email protected]> wrote: > Glad to finally get this question in front of people who might be able to > help. Sorry in advance for the long post; just trying to be thorough for > good measure :) > > I very recently dove into the circuit-building hobby, specifically Nixie > clocks. The PV Electronics kit seemed like a pretty good starting point > for someone with undeveloped solder skills, and even less electronics > knowledge, to work at expanding both. I would say this has definitely been > the case, but it hasn't been without the expected learning curve. > > I completed the low voltage and high circuits per their directions (QTC > clock instructions & diagram pdf > <http://www.pvelectronics.co.uk/kits/qtc/qtc_v11a.pdf>) and ran the > simple voltage tests across the 5V and 175V portions, all went well. I > subsequently added the remaining components, and began the final test to > light up a tube. The seconds-place position worked great, just as I'd > hoped, but moving to the minutes position didn't work out so well. > Plugging the power supply into wall yielded a number of effects, none of > them good. > > -Something going sizzle... > -The minutes tube either drawing voltage backward, or cathode-to--cathode, > with purple flashes at its lower interior portion (this the same tube that > ran fine in the seconds position) > -All RGB LEDs which had previously illuminated blue (the default start > condition, I assume) were now fully lit to make a violet color (all > elements full blast) > -Before promptly yanking the power supply after a second or so, I saw all > these signs start to fade or draw down (brightness and sizzle) > > So, the project fried, I discharged all capacitors and set to (more) > carefully inspecting my handiwork. I found what I thought was a single > tiny solder bridge that may have shorted one of the resistors in series > with an RGB LED and fixed it, but I wouldn't think that would cause such > theatrics. I assume that there was a short or polarity-swap in the second > Nixie socket, which I guess could allow more driving current than desired > and cook some things (the transistor at each Nixie that I assume is acting > as a control relay, the logic IC controlling those transistors, the MOSFET > supplying the high voltage, or the voltage regulator supplying the low) > > -As best I can tell, the switching transistors for each tube look intact > (no obvious burns, cracks, etc.) but I don't think I can test them easily > while soldered in place > -The anode IC and cathode IC look intact, though again, no way to tell if > they are burned internally > -I did a resistance check across all capacitors, and they are > charging/discharging, though I don't have a great way to measure Faradays > (just a multimeter) > -All diodes appear to still be resisting current in the right direction > -The 5V power supply circuit is still testing good > -The high voltage power supply was not amplifying (12V in, 13V out instead > of ~175V) > > The last point suggested that voltage amplifying transistor was shorted > and non-functional, so I removed it (it easily broke apart as I did so) and > replaced it. The high voltage circuit still reads the same afterwards, as > are the fully lit LEDs (no sizzle, though, and only the 'red' is > illuminated after removing the solder bridge), and that is as far as my > problem solving has carried me. One point worth mentioning, is that the > board is attempting to draw too much current, which causes the > self-resetting fuse to disengage (the "fading" I saw initially also > occurred during this subsequent testing of the HV circuit, but momentarily > shorting the fuse lit the LEDs right back up). > > I'm a mechanical design engineer. This stuff ain't my bag, not yet > anyway. But as best I can tell, the logic side of the circuit diagram > suggests the 'anode' IC can tell it's not getting 175V and may be lighting > the LEDs fully by default (as opposed to those connections being cooked, > which I'd assume would cook the LEDs themselves). The 'cathode' IC > directly meters the needed juice to the Nixies, so it is possible/likely it > was damaged during the high current excursion, but there is not the > visible/olfactory signs I'd expect of the distinct sizzling I caused. I > don't think the 'anode' IC could be exposed to damaging current from the > Nixie portion of the board, unless both layers of switching transistors > shorted source-drain (I'd think this would also cause some dramatic results > in the 6 transistors involved). So, my theory is that the problem still > lies in the high voltage generation circuit...somewhere. I suppose I could > blindly start replacing stuff, but I'd like to at least chase the most > likely issues first. > > To anyone who made it this far, and has a suggestion, I salute you. Many > thanks, regardless. > > TCB > > -- > You received this message because you are subscribed to the Google Groups > "neonixie-l" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > To view this discussion on the web, visit > https://groups.google.com/d/msgid/neonixie-l/7cf1fb99-10ae-4260-9a93-402c3ee04d0e%40googlegroups.com > <https://groups.google.com/d/msgid/neonixie-l/7cf1fb99-10ae-4260-9a93-402c3ee04d0e%40googlegroups.com?utm_medium=email&utm_source=footer> > . > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send an email to [email protected]. 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