Hi,

I've been fortunate enough to acquire a HP 115CR Frequency
Divider/Digital Clock - it's electromechanical and I suspect built in
the mid/late 60s - just slightly older than your humble correspondent.

It's similar though not identical to the 115CR shown here
http://www.leapsecond.com/hpclocks/

I'd like to fire it up - given it's age my thought was to use a current
limited 24V bench supply and slowly ramp up the voltage the first time -
would welcome any thoughts on this.  I gather from the supporting
documentation for the powersupply it's rated at drawing ~250mA

I've been unable to locate a scan of the owners manual or service manual
online.  Have looked at time-nuts archives, leapsecond.com and hparchive
to no avail.  There does appear to be a hardcopy available for purchase

• happy to fall back to this if necessary, but any pointers welcome.

My goal ultimately is to have it on display running, synchronised to a
GPS disciplied 10MHz source :)

Any thoughts and feedback welcome - this is my first foray into old
clocks :)

Kind Regards,
Hugh
VK3YYZ/AD5RV

Hi,
I have the complete manual of the HP115BR. Pse contact me directly to send you the file.
If you need I can suggest some service activity normally are needed by this old clock.
Luciano,
timeok@timeok.it

From "time-nuts" time-nuts-bounces@febo.com
To time-nuts@febo.com
Cc
Date Fri, 23 Dec 2016 10:29:01 +1100
Subject [time-nuts] HP 115CR Clock Powerup / Documentation
Hi,

I've been fortunate enough to acquire a HP 115CR Frequency
Divider/Digital Clock - it's electromechanical and I suspect built in
the mid/late 60s - just slightly older than your humble correspondent.

It's similar though not identical to the 115CR shown here
http://www.leapsecond.com/hpclocks/

I'd like to fire it up - given it's age my thought was to use a current
limited 24V bench supply and slowly ramp up the voltage the first time -
would welcome any thoughts on this. I gather from the supporting
documentation for the powersupply it's rated at drawing ~250mA

I've been unable to locate a scan of the owners manual or service manual
online. Have looked at time-nuts archives, leapsecond.com and hparchive
to no avail. There does appear to be a hardcopy available for purchase

• happy to fall back to this if necessary, but any pointers welcome.

My goal ultimately is to have it on display running, synchronised to a
GPS disciplied 10MHz source :)

Any thoughts and feedback welcome - this is my first foray into old
clocks :)

Kind Regards,
Hugh
VK3YYZ/AD5RV

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Hiya,

My thanks for the various replies including to Luciano for the 115BR
manual and Chuck for the timely advice about old caps!

I'll take a put at summarising the various replies and my own
observations now I've the 115BR Manual and the 115CR unit itself - any
errors in same mine alone;

The 115CR appears to be a slightly later device - it's 2RU rather than
3RU and uses plug in PCBs rather than point to point/tag strip style
construction.

Based on a quick glance at the 115BR service manual and the 115CR unit
itself, I'd venture they are electrically and mechanically very similar,
possibly identical.

The 115CR seems to have hard wired DC input polarity relative to ground
wheras the the BR is switchable.  The 115CR doesn't have a meter or as
many frequency output options.

Maintenance wise;

• Divider circuits need to be manually started using internal switches,
  the unit has built in rack rails to support easy access.  Similarly the
  motor must be manually started.

• Many of the silver can (physically larger) axial capacitors on the
  PCBs in my unit show signs of corrosion - this presumably the acid
  leaking out of the tantalum caps as Chuck alluded to.

• One correspondent suggested replacing the caps right from the word go,
  another to go for broke and turn it on - not sure which way I'll go yet ;)

• The mechanical odometer style display needs care not to bind up/jam.
  Attention to lubrication/grease for the motor and other bearings seems
  prudent.  Don't force any of the mechanical components.

• Looks like I can get a paper manual here
  http://www.etestmanuals.com/Search.aspx?Search=115CR - I think this will
  be my next step.

I'll close for now with this quote from Chuck which may dash my plans to
have it on permanent operating display;

"These clocks are not a lot of fun to live with.  They sing along
quite loudly at 1KHz."

...so might not be ideal in the otherwise quiet lounge room after all :)

Thanks again all for the input so far, will report further progress when
I return to the device in the new year after a house move :)

Cheers,
Hugh

Got a 113BR clock many years ago because it looked like the clock in the
Smithsonian. Used a 103 precision OCXO for the source.

It is noisy. That's part of why it has a heavy metal case. I expect that
a rebuilt stepping motor might have been quieter. I kept it in a larger
wooden box lined with R19 fiberglass insulation. I used an insulated
wooden front door held by magnetic catches to close the box, had to
remove the door to see it.

The manual reset is a feature. If the clock stops for any reason, it
stays stopped. If it restarted by itself it would authoritatively show
you the wrong time. A battery and float charger are required if you want
to see how much it varies in a year.

If all you want is a technically attractive clock, talk to a watchmaker
about driving it with a synchronous clock motor. Or do your own 10 Hz
stepping motor (or whatever gear ratio is easy).

Best of luck
Bill Hawkins

-----Original Message-----

• Divider circuits need to be manually started using internal switches
  [snip] Similarly the motor must be manually started.

"These clocks are not a lot of fun to live with.  They sing along quite
loudly at 1KHz."