[time-nuts] FEI FE-5680A Rubidium Pinout
JimMeek at sbcglobal.net
Tue Sep 20 01:17:36 EDT 2005
On Mon, 19 Sep 2005 12:58:19 -0700, Rex <rexa at sonic.net> wrote:
> 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.
Hmmmm. I must have found by ohmmeter the connection between the eeprom
and the rubidium via J2-14A, not realizing they were both inputs (as I had
concluded that the pinout was non-standard). I not sure about what I
found out about the connection of the rubidium serial output, but I seen
to recall that it doesn't just end electrically where it does visually,
rather "goes underground" through the inner layers of the board and
elsewhere in the circuitry.
Work pressures caused me to back-burner further analysis, and I've yet
to get back to it.
> 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.
Many thanks for this info. I was reluctant to power up the whole board,
before doing further circuit tracing.
> 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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