[time-nuts] FEI FE-5680A Rubidium Pinout

Rex rexa at sonic.net
Mon Sep 19 17:04:52 EDT 2005


Seems parts of this discussion have gone offline.

Posting this reply, I made, to the group.


On Mon, 19 Sep 2005 07:09:10 -0500, Brian Kirby <kirbybq at bellsouth.net>

>I would love to look at a dump of the EPROM, but I have no way to dump 
>it myself, at the moment.
>Anybody else, up to the task ?

I did some tracing on the board this morning. I don't think there is
going to be anything enlightening in the eeprom. It doesn't seem to have
any on-board interface to the rubidium. All of its control pins seem to
go to the big external connector J2 as follows...

X25020   J2
------   ---
 SO(2)   12A
 SI(5)   14A
SCK(6)   15A
 WP(3)   13A
 CS(1)   11A

So the eeprom seems to be a scratch pad for some external function. The
external connector for the board, J2, is a big rectangular connector
with pins 2-18 by A-E. It was chopped up on the unit I received,
presumably because the board was scrapped.

I traced the two rubidium serial interface pins across the board too.
Serial out seems to dead-end in a section that has not been populated
with chips. Serial in comes from J2-14A.

If you want to power up the rubidium on the board, you can feed the
board just +15 V on the six pins, J2-14C-E and J2-15C-E. Ground can be
connected on the edges of J2...  J2-2A-E and J2-18A-E, or to the big
heat sink section. The 5V is generated on board by the 2941.

10 MHz from the rubidium goes to J2-6D. The 1 pps output goes to the
logic chips, U10-6 and U6-?, so I assume they count up pulses in some
way. I didn't trace out the details.

So I don't see anything on the board that gives any greater hint how to
control the function or frequency of the rubidium.

If we ever learn more about the control (assuming there is a way) of
this rubidium, I think it will be by finding access to docs on the
Motorola cell equipment it came from. Here's a link that mentions the
SGLA400B: http://www.cellsiteind.com/w.Motorola.html . I sent an email
to them, but got no reply. 


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