NOt pin-compatible but functional compatible and available is the 74C00
or74 HC00, which has a long life I am using one in my gate alarm
since1989, it is on all the time and the chip is available the HEF4011
is also available -- at Mouser -- it is pin-compatible and function
with CD4011 ad it is made by Philips [NXP]
73
KJ6UHN
Alex
On 4/3/2017 4:43 PM, Jeremy Nichols 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_equipm...@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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