No, not trivial Nick. And I do believe it is heat when driving IN-18s. Too much of that nasty stuff is generated for whatever reason and components fail. I have experimented with setting the voltage way down to 160 and added ventilation to the one that is enclosed, but still after time they fail. For whatever reason these electronics are more susceptible to heat than all other muxed designs I have.
On Friday, September 2, 2016 at 2:22:02 PM UTC-7, Pramanicin wrote: > > Michael, sorry to hear you're having issues. I've built probably more than > 30 of these things over the last 10 years for friends and family and have > only had one issue so far (bad DS1307), Jonas was very helpful in helping > me diagnose. Did you reach out to him? I was never happy with the lack of a > good heatsink at the regulator and mosfet (the board plane didn't seem > enough to me, but I'm no expert in the least) and always added a small > custom heatsink under the 7805...maybe heat is your enemy in a case? > Apologies if this seems a trivial point to make! > > Cheers, > > Nick > > On Fri, Sep 2, 2016 at 2:08 PM, MichaelB <[email protected] > <javascript:>> wrote: > >> Thanks for the advice Martin. I may as well change the MOSFET before >> buttoning this thing back up in it’s case. I have plenty of them. I could >> certainly add another diode in series if this is the general consensus. I'm >> really in no hurry to button it back up if it means fixing these recurring >> issues. >> >> >> >> >> On Friday, September 2, 2016 at 1:08:47 PM UTC-7, Dekatron42 wrote: >>> >>> Some time ago John Taylor (Tayloredge) converted a wall wart into a >>> Nixie PSU and showed the result here on the forum, after that I started to >>> experiment with other small switching power supplies. In the answers to my >>> questions John mentioned better rectifier diodes and also that he used two >>> in series. I tested two UF4007s in series and found that the switcher >>> worked a lot better, with one it sometimes blew up and caused a lot of >>> collateral damage to the rest of the switcher. At the same time I pulled >>> out a few switchers I had lying in a box like the ones here and I added a >>> second rectifier diode to those too and they also worked a lot better. I >>> can't explain this as I know too little about electronics in this area but >>> I am sure that others can. I also discussed snubber and found that I could >>> skip those if I used two UF4007s in series as it looked good enough on a >>> scope then. The result with two diodes in series was that they didn't blow >>> up but I also got a lot cooler inductors which also led to less heat in the >>> switching transistor so there was a lot less power loss in the switcher. I >>> tested this change on both switcher with a single inductor and also on >>> switcher which uses an isolated transformer. I wish I knew more about this >>> so that I could explain it properly but unfortunately I don't. >>> >>> Don't forget to replace the mosfet if you have blown the inductor as the >>> mosfet has seen a lot of stress during these situations and is probably >>> partially damaged. I have had to replace the mosfet on several occasions >>> even though it at first seems to work well. >>> >>> /Martin >>> >>> On Thursday, 1 September 2016 19:51:45 UTC+2, MichaelB wrote: >>>> >>>> Had another TubeHobby clock start blowing fuses the other day and I >>>> know others on this forum have had similar issues. I have 4 of these muxed >>>> clocks and 2 that drive IN-18’s, the others use smaller tubes like the >>>> Z566M and the Z574M and have been fine. However, I have had issues now >>>> with >>>> both of the IN-18 clocks where the 1st blew C6 (see attached PS >>>> schematic) and now this one has eaten (shorted, or darn near, measures >>>> .3ohms) the 270uf inductor. Replaced it and the clock has run fine now >>>> for >>>> 3 days, so its fixed for now. Not sure what it is about this clock's power >>>> supply driving IN-18’s and so wondered if others have noticed this problem >>>> and what a long term cure might be? Included the power supply schematic >>>> for >>>> review. >>>> >>> -- >> 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] <javascript:>. >> To post to this group, send email to [email protected] >> <javascript:>. >> To view this discussion on the web, visit >> https://groups.google.com/d/msgid/neonixie-l/961809a3-2d54-490d-a6d9-360d14c9a7a2%40googlegroups.com >> >> <https://groups.google.com/d/msgid/neonixie-l/961809a3-2d54-490d-a6d9-360d14c9a7a2%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]. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/b41bcae6-5a47-4dec-8e09-3a44aaa0bf01%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
