Michael, I have to comment on the logic here. You say you have one that is quite OK and seem to use that fact to rule out the effects mentioned by Nick. Actually, I consider that the parasitic oscillations idea is reinforced by your fact, not denied by it. When a circuit is on the verge of misbehaving there will be some that are OK and some that aren’t.
Obviously I can’t tell from here what the actual fault is. Capacitors. I am interested in the topic. Low ESR electrolytics are a curse. [Remember that fuss about the “stolen” formula not being complete and all the computer manufacturers being affected?] Some do seem to last better than expected. Some fail quickly. The LED lighting industry is possibly going to cause improvements. Those tiny electros that they hide in the base of the globe really are stressed. And some sellers still quote the expected LED life as that for the power supply too ! Oops. [And Australian consumer law provides for lifetime warranty btw, regardless of what the manufacturer states. And we beat up Steam to the point that they allow returns!] I am very interested in hearing about how well different brands and types of capacitor perform. Anyone tried non-electros? I have noticed that some switching supplies driving discharge tubes for TV and laptop backlighting [yeah, old ones, not LED ones] use monolithic solid caps. One I fixed had only 2uF though iirc. A pity that opamp capacitor multipliers don’t store energy J . John K Australia From: [email protected] [mailto:[email protected]] On Behalf Of MichaelB Sent: Sunday, 7 April 2019 11:06 To: neonixie-l Subject: Re: [neonixie-l] Another Tube Hobby Failure HI Nick, I know you have mentioned that before, but I really don’t think anything else is wrong. As I said I have another one of these with 566M tubes and it has worked flawlessly for 8+ years. Those electronics are in a similar enclosure with less ventilation. And this is the second set of electronics i have tried in this enclosure thinking there might be something internally wrong with the PCB. (I had that problem with one of my Thomas clocks way back when) But, I believe others have had issues with these electronics. Another variable vs. your clocks might be that I have wired in a pair of NE-2 Colons in parallel vs. the stock config that uses just one per each side. I doubt that would be an issue, but it may account for a slightly greater current demand. I don't think these clocks like anything, but an open air set up. Also, the close proximity of the 5V VREG and the IRF640 is somewhat suspect from a heat dissipation perspective. Anyway…I used a higher voltage capacity electrolytic this time, maybe I’ll this'll give me another year or so :-). and I will try your idea of adding a heat sink to the VREG, since heat seems to be the culprit here. Thx Nick On Saturday, April 6, 2019 at 6:06:36 PM UTC-7, Pramanicin wrote: Something else is awry there Michael. I have a friend with a TubeHobby IN18 that i built for him that’s been running for well over 6 years now with no issues. The only modification i ever made was putting an extra heatsink on the regulator as what was there (board plane) didn’t seem sufficient to me (just a hunch, I’m sure Jonas knew what he was doing..).... Hope you get it sorted! Sent from my iPhone On Apr 6, 2019, at 17:15, MichaelB <[email protected] <javascript:> > wrote: This makes 4 times now this clock has failed over the past 10 years or so. This is a stock clock with IN-18's. I have another set of these electronics that has never failed, but then again, I had changed the tube board to accommodate the Z566M tube. Different current demands? It has worked like a charm for years now. The failure with the IN-8 clock this time was a leaky C6. In the past the inductor has failed, but usually its one of the electrolytics in the Pwr supply stage. It's become kind of a ritual where every 2-3 years I have to pull the clock apart and play detective and figure out what's wrong after its starts blowing fuses. Kind of fun now, actually! -- 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/07394dde-1d45-4e3f-a38a-75ca15d16c48%40googlegroups.com <https://groups.google.com/d/msgid/neonixie-l/07394dde-1d45-4e3f-a38a-75ca15d16c48%40googlegroups.com?utm_medium=email&utm_source=footer> . For more options, visit https://groups.google.com/d/optout. <Tube Hobby Pwr Supply Schem..jpeg> -- 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/22340da1-4f58-4673-bb1d-a9bdebb8fd14%40googlegroups.com <https://groups.google.com/d/msgid/neonixie-l/22340da1-4f58-4673-bb1d-a9bdebb8fd14%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/005d01d4ed02%24709a87c0%2451cf9740%24%40internode.on.net. For more options, visit https://groups.google.com/d/optout.
