[time-nuts] Service info for HP/Symmetricom 58502A 10MHz distribution amp?

John Stone johns at ks.uiuc.edu
Thu Jan 12 12:09:20 EST 2017

  I've got an HP/Symmetricom 58502A 10MHz frequency reference
distribution amplifier.  It has two 10MHz signal inputs and it 
auto-switches between inputs if one of them goes down.  

The 58502A had been working fine for the couple of years that I've had it, 
but recently it failed in a strange way where it thinks it has
input signals on both A and B inputs even when no signals are present,
and when when signals _are_ present, they don't make it to the
outputs, even if I tell the controller to hard-select one of the inputs
via SCPI commands over the RS-232 port.  The hardware status lights
display consistently with the erroneous interpretation of input signal state.

The User's Guide which contains only a simple block diagram 
that shows a 2-to-1 switch on the inputs that feeds status to the 
microcontroller, and funnels the active input to the 1-to-12 
output amplification and isolation block.  I'm ready to crack it open
and start poking around now, but I was hoping a time-nut might have 
experience or suggestions with these units and/or a service manual
if such a beast exists.

  John Stone
  johns at ks.uiuc.edu

NIH Center for Macromolecular Modeling and Bioinformatics
Beckman Institute for Advanced Science and Technology
University of Illinois, 405 N. Mathews Ave, Urbana, IL 61801
http://www.ks.uiuc.edu/~johns/           Phone: 217-244-3349

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