B&F Enterprises "Digital Clock" flakes out

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7 years 4 months ago - 7 years 4 months ago #4837 by Ty_Eeberfest
Power supply components, especially that transformer, will heat things up a bit. Tubes too, but not nearly as much as the power supply. Heating was probably not enough to matter when everything was new and fresh. But that clock isn't new and fresh anymore and the temperature rise could aggravate anything from a dodgy solder joint (or trace) to a component that's getting "weak".

If you are fortunate enough to be able to reproduce the problem at will, there is (used to be?) "freeze spray" sold at electronics shops for troubleshooting this sort of thing. It's been years since I've used it but it was useful for finding thermal intermittents in hot stuff like tube TV sets. If "freeze spray" has been banned (I think it was Freon) you can always get freezing liquid by spraying a duster can upside down B).

Look into it later when the dust is clearing off the crater.
Last edit: 7 years 4 months ago by Ty_Eeberfest.

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7 years 4 months ago #4841 by Dr. Optigan
Another update:

I put the metal cover back on a couple of days ago as an experiment, and it has continued to run correctly, so overheating probably wasn't the cause. My guess is that the board tapping test somehow undid whatever was messing up, but given that there isn't a lot of mass to your average Sharpie marker, I'm guessing it's not perfectly stable. I'm not ready to call it fixed, but at least it hasn't screwed up in several days. I'll take the board out of the case at some point in the near future to attempt a more permanent fix, but for now, here's a crude picture of the clock up and running:



Thanks for all the help thus far!
-Adam

PS: Freeze spray is still available; it just uses R-134a refrigerant instead of Freon. I have a can of MG Chemicals Super Cold R-134 which has come in handy in the past.

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7 years 4 months ago #4842 by Dr. Optigan
Oops, spoke too soon... :angry:

Woke up this morning, looked at the nixie clock, and it was showing 00:00:00. Shortly afterwards, it started showing 28:35:xx. Looks like the problem has returned. Gonna pull the board, and re-seat all the chips (cleaning the pins and sockets at the same time using contact cleaner). Hopefully, this'll do the trick, but this is getting rather frustrating... :unsure:
-Adam

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7 years 4 months ago - 7 years 4 months ago #4845 by Ty_Eeberfest

Dr. Optigan wrote: Hopefully, this'll do the trick, but this is getting rather frustrating... :unsure:


So have you done any of the things I suggested, to wit: clean all that godawful flux off the board and then inspect / retouch solder joints?

Look into it later when the dust is clearing off the crater.
Last edit: 7 years 4 months ago by Ty_Eeberfest.

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7 years 4 months ago #4848 by Dr. Optigan

Ty_Eeberfest wrote: So have you done any of the things I suggested, to wit: clean all that godawful flux off the board and then inspect / retouch solder joints?


I hadn't at the time, due to the tap test seemingly having had an effect. However, I gave the solder joints a brushing with 91% isopropyl alcohol after re-seating the IC pins earlier. Didn't do a whole lot to the ancient rosin, but it seems to have gotten rid of some of it. I'll give it a whirl once the board has dried.

Anyway, here are some pictures of the component side of the board, as promised:




Mostly 7441s, 7490s, and 7492s, with a 7410 in there. Still not sure what design this thing is based off of. Any ideas?
-Adam

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7 years 4 months ago #4849 by Ty_Eeberfest

Dr. Optigan wrote: Still not sure what design this thing is based off of. Any ideas?


Yep, I recognize the design. See the attachments on Post #1 and Post #7 of this thread:

www.tubeclockdb.com/forum/Builders-Forum...e-clock-problem.html

May not be an exact copy but it's really damn close.

Look into it later when the dust is clearing off the crater.

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