Hello, Steve,
depending on how I change the ICs the clock seems to run or not.
What I couldn't get away from is that some numbers are skipped
when setting the clock. This is annoying if you jump from min 58
to 60 then the minutes do not fit anymore. Much more strange is
that the display Data Hold does not go off when the clock is
running and also no matter if the clock is running and has a
plausible time or not always a time error is displayed. If I
remove the J-K flip-flop on the PCB these two indicators are off.
The device seems to be intact but I had exchanged it for an
identical one. I would exchange the other devices if HP had not
used Inverse Logic devices for the counters. Or is there a cheap
replacement for 1820-0119 and 1820-0116?
I would hate to build my own replacement for that...
Due to the inverse logic and the speed, the devices cannot be
tested on my current IC Tester... I suppose that the tester can
check HC and LS devices, so it has something to do with speed? Or
what is the reason that SN74xx devices can not be tested with most
IC testers that are available at eBay.
Many greetings from Germany
Philipp
Am 21.04.2020 um 18:43 schrieb Stephen
Hanselman:
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Philipp,
?
What is the clock doing/not doing.? I went
looking for our manuals and it seems they did not survive the
purge.
?
One thing to do as a preventative measure
is to look at the row of chips next to the NIXIE tubes.? In
between them (I think I¡¯ve got the position right) are
resistors.? These are the current limit resistors for the
NIXIEs and they get hot enough to burn the board.? We always
replace them, installing about a 0.25 in above the PCA.?
?
The circuit for this part is very similar
to the display section of the 5327B.?
?
We built a replacement clock that actually
remembers who it is when the power is cycled so all of the old
stuff got packed.
?
I¡¯ll talk to my partner but I can¡¯t find
the spare boards of manuals we used to have
?
Steve
?
?
Hello,
maybe anybody has a service Manual f¨¹r the K21-5321B Digital
Clock.
My clock dosent work the right way. I already tryed swaping
ICs but i think that more than one is faulty...
Best regards from Germany
Philipp Gr?mer
