Author Topic: HP5216A 12.5MHZ Counter Nixie Tubes  (Read 9203 times)

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Offline zike

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Re: HP5216A 12.5MHZ Counter Nixie Tubes
« Reply #50 on: December 28, 2017, 10:10:37 pm »
So it appears "attached" by relevance... (despite thread being dormant over a year...)

I just fixed a 5216A with a peculiar, but ultimately similar, problem. At first I thought it was  grossly out of cal, but the error was huge and changed depending on the sampling time/decade; whereas the well-aged internal crystal was dead nuts (<0.1 ppm error!).

Turned out the 5th digit appeared superficially to increment (even carried  tens to the 6th digit),  *except* it skipped 2, 3, 6 and 7.  Somehow that digit's 1820-0093 decade counter (predecessor of the faulty 1820-0119 above) had a stuck bit, but still worked otherwise; it just divided by 6, instead of 10!

I surmised the 1820-0093 and -0119 IC pinouts were identical, based on schematic backdates. Indeed, a -0119, pulled from a later-model counter with other issues, works fine in place of the failed -0093. Which is lucky as the -0093 appears even more $$$ "unobtainium". 

Also worth noting, these parts (and the unusual upside-down Burroughs B-5560 Nixies) are shared with the lesser 5221A and 5321A 'economy' counter models, which are more common, and less worth fixing.

Hope this info helps someone else down the line.


Offline bitseeker

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Re: HP5216A 12.5MHZ Counter Nixie Tubes
« Reply #51 on: January 03, 2018, 12:28:51 am »
Thanks for the substitution info, Zike.

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