[time-nuts] Any FE-5650A help our there?

Azelio Boriani azelio.boriani at screen.it
Tue Mar 11 18:08:09 EDT 2014

Elio (in 2012) has done some work on the FEI rubidium

On Tue, Mar 11, 2014 at 10:44 PM, Skip Withrow <skip.withrow at gmail.com> wrote:
> Hello Nuts,
> Looking for some help with an FEI FE-5650A.  This is one of the units that
> is surplus from the telecom industry with the Option 02 serial interface.
> Unit was working fine - locked, and was able to control the frequency by
> issuing commands to the serial port.  Then something funny happened,
> oscillator went unlocked and cycling the power does not help.  I have
> dumped what data I can (see attachments) and the software inside the 5650
> appears to be corrupted.
> Attached are two files, one from a good 5650A and one from the bad 5650A.
> It appears that several of the data areas have been over-written with the
> 9-byte sequence 2D 09 00 24 00 00 00 00 24.  This would be the response to
> the 2D query command, except the data in the frequency register was
> probably not 00 00 00 00 at the time of failure and 24 looks like the
> checksum for the header and is not the checksum for 00 00 00 00 (which
> would be 00).
> Is there an ex-FEI engineer out there in time-nuts land?
> Has anyone else seen such behavour?
> Is there any known way to reset the software for the 5650?
> Has anyone dumped the 5650 microcode (I vaguely recall one of the rubidiums
> having been dumped)?
> I took the processor board from a good 5650 and put it on the bad unit and
> it locks fine.  My next step is to write a control word to the bad unit
> then read it back and see if it shows up in the memory dump, to see if the
> memory over-write is dynamic (the program has been premanently changed) or
> if it looks like it happened only once.
> Any information would be helpful, or suggestions on debug.
> Thanks in advance.
> Skip Withrow
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