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

Hugh Blemings hugh at blemings.org
Fri Dec 23 18:24:17 EST 2016


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 

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 :)


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