I have one of these clocks too and it fails every three years or so on average. It’s all down to C6. Sometimes just F1 fails and other times the inductor L1 goes short circuit as well. The Equivalent Series Resistance (ESR) of C6 goes through the roof, causing it to effectively be a capacitor in series with a resistance. This result is ringing in L1, and instability in the output voltage which increases L1’s heat dissipation and untimely failure. Ambient temperature is definitely a factor in C6’s lifespan, i.e clocks running in cooler climates may run longer before failing, but the real mechanism of failure is C6’s ability to withstand the internal heat generated by the pulse current as its ESR rises with age. The higher it’s ESR, the warmer it runs, then the quicker its electrolyte dries up. High quality, low ESR 105 degree electrolytic capacitors designed for pulse applications like the Panasonic WL-R series will have a longer life than ‘ordinary’ electros but eventually even they will fail. I have thought about substituting a Multilayer Ceramic Capacitor in place of electrolytic C6, but currently waiting for the next failure (which is about due!) before I experiment with them. Perhaps another person can comment on their suitability for such an application?
Regards from Australia! > On 7 Apr 2019, at 11:59 am, Mac Doktor <[email protected]> wrote: > > >> On Apr 6, 2019, at 9:36 PM, MichaelB <[email protected]> wrote: >> >> I used a higher voltage capacity electrolytic this time, maybe I’ll this'll >> give me another year or so :-). > > Are you using 85°C or 105°C? > > >> and I will try your idea of adding a heat sink to the VREG, since heat seems >> to be the culprit here. Thx Nick > > Never turn your back on a 78xx. You could try using a 317 instead (requires a > resistor). > > > Terry Bowman, KA4HJH > "The Mac Doctor" > > -- > 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/0DFF2801-AAC9-4780-9779-E01A35F1612D%40gmail.com. > 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/E8DFC0C0-142E-409C-AF68-EBDAE32AF0D0%40gmail.com. For more options, visit https://groups.google.com/d/optout.
