[time-nuts] [Summary] HP 115CR Clock Powerup / Documentation

paul swed paulswedb at gmail.com
Fri Dec 23 20:50:43 EST 2016

Looks like you have great advice. But I will add if the tantalums show the
corrosion do not fire it up. Unless you like smoke and other damage. A good
way to extend the time you will spend getting it going and cleaning up the
acid all over everything. Lots-O-fun.
Good luck and I have always heard the mechanics were the challenge. No real

On Fri, Dec 23, 2016 at 6:24 PM, Hugh Blemings <hugh at blemings.org> wrote:

> 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/Se
> arch.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
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