[time-nuts] HP-59309A Clock counts only seconds

Bob kb8tq kb8tq at n1k.org
Mon Apr 3 21:52:44 EDT 2017


A lot of the early IC’s were packaged in the era of “learning by doing”. The
net result is that some of them do indeed have process related packaging 
“use by dates”. On top of that the early IC processes were not as fully 
worked out as the more modern ones. Things like metallization thickness 
turned out to be on the skimpy side in some cases. The other nail in the 
coffin is input and output protection. The hazards of ESD and device upset
were not handled as rigorously early on.  The net result is that depending on 
*any* IC that dates back ~30 years is a bit of a gamble. 


> On Apr 3, 2017, at 7:43 PM, Jeremy Nichols <jn6wfo at gmail.com> wrote:
> I have a new-to-me HP-59309A HP-IB Digital Clock. The clock works on both the internal crystal oscillator and on an external 10 MHz standard (GPSDO). However, it counts only to 60 seconds and then repeats without updating the minutes digit. The TIME SET (FAST and SLOW) push-buttons work but again, the count will not update minutes and hours, only seconds. The DAY SET procedure works correctly for days and months. All the other switches and buttons do what they are supposed to do. Using my 10526T logic pulser I can force the minutes and hours counters to work. The power supply is in good condition (after replacement of a few components) and I see no other problems (yet).
> Tracing the clock signal through the logic circuitry brought me to U3 on the A4 board. This (U3) is a 4011 quad 2-input NAND gate in a 14-pin DIP package. It "connects" the seconds counter to the minutes counter and appears to have failed. One of the people on the email list <hp_agilent_equipment at yahoogroups.com> commented that the 4000 series CMOS chips have a known limited lifetime. Since these parts are no longer in production, the writer expressed the concern that any parts I might find to buy may be DOA.
> Before I go hunting for parts, I'd appreciate hearing from anyone in the group who has experience with the 59309A Clock and/or the 4000-series CMOS family. In particular, are there modern equivalents to my 4011 chip? If the 4000's really do have a limited lifetime I'd rather use a substitute.
> Jeremy, N6WFO
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