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

[Tom Miller]

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" <jn6wfo at gmail.com>
To: <time-nuts at febo.com>
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 
> <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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