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

Tim Shoppa tshoppa at gmail.com
Mon Apr 3 21:47:24 EDT 2017

CMOS availability has held up pretty well because of its wide voltage
range. Mouser has over eleven thousand CD4011BE's in stock:

I can't rule out an old logic gate dying, but I would suspect this first:
Some clocks were made or modified to be tied to external minute and/or hour
synchronization pulses and these inputs can hold and jam zeroes into the
minute and hour counters.

Tim N3QE

On Mon, 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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