4000 series logic is just fine. Just replace the original parts with like.
http://www.ebay.com/itm/CD4011CN-CMOS-Quad-2-Input-NAND-Gate-5-pcs-/272579598216?hash=item3f77029788:m:mSmV7o8qfGTPl04DaSu3DSw
Regards
----- Original Message -----
From: "Jeremy Nichols" <[email protected]>
To: <[email protected]>
Sent: Monday, April 03, 2017 7:43 PM
Subject: [time-nuts] HP-59309A Clock counts only seconds
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
<[email protected]> 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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