Scrub the C3/C4 check, you mentioned that it was functioning OK on the seconds, so that's no an issue....apologies for that! ;-)
On Thu, Jan 15, 2015 at 7:50 PM, Nicholas Stock <[email protected]> wrote: > 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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