First we need some clarification of the problem, as your original post contains a discrepancy. At one point you say the 10 minute tube is not counting correctly, then later you say it is fine. This is probably a typo, but let's hear the answer.
Nick, the 10s are driven by 92's and the 1s by 90's. Another minor correction for clarity. Here is where I would break out the logic analyzer and hang some probes, watch the count sequence. This appears to be a case of the counters not resetting properly as they roll over from 5 to 0. This could be for a number of reasons, maybe the parts are faster than the used to be, subtle changes in setup & hold times can occur with die changes, shrinks, technology changes, etc. Maybe a ringing clock that never used to be a problem is now.. USB based logic analyzers are handy tools, and have gotten pretty cheap. Check the counting with & without the 74141s installed. If they are loading the counter outputs, they could affect the count sequence, as some outputs are also used internally on the counters to sequence the F/Fs. Terry On Wednesday, March 8, 2017 at 9:07:27 PM UTC-6, Nick wrote: > > ...Also, reading your problem description isolates the issue to the 10s > digits. > > The 10s are driven by 7490s whereas the units are driven by 7492s. Do you > have the right chips in the right places? > > I'd also try swapping round the 74141s between the 10s and units to see if > the problem moves with them - 74141s can fail.... > > Isolate the problem. > > Nick > > -- 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 neonixie-l+unsubscr...@googlegroups.com. To post to this group, send an email to neonixie-l@googlegroups.com. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/a5e0ea98-e917-4937-a72a-118522f73fe5%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
