[time-nuts] One sure way to kill your FE-5680A or FE-5650A

Bob Camp kb8tq at n1k.org
Tue Jun 7 18:11:09 EDT 2016


Thanks for the heads up !!

It almost sounds like they are doing some sort of “use flash as eeprom” trick and not 
quite getting it right. Maybe updating a “how many times turned on” counter in that 
memory space.


> On Jun 7, 2016, at 5:22 PM, Skip Withrow <skip.withrow at gmail.com> wrote:
> We recently had a customer that purchased an FEI FE-5650A (basically a
> repackage version of the FE-5680A) and reported that it worked for several
> hours, then died.  We promptly sent another unit, and he reported that it
> died as well.  He had nothing but power hooked to the unit.
> On return of the first unit, it was examined and found to have corrupted
> code.  The corrupted code problem was thought to be associated with doing
> bad things to the serial port (like framing errors), and we still believe
> this to be the case.  However, the customer said only power was connected
> to the unit.
> I was asking some questions about how he was powering the unit, when he
> said he turned on the power supply (a large HP variable supply) and turned
> the voltage up to +15V (our 5650's are single supply).  Ah hah, slowly
> ramping the voltage up on these oscillators appears to be a no no.
> The second oscillator has now been examined and it too was confirmed to
> have corrupted code.  So, the word of warning is - DO NOT slowly ramp the
> supply voltage of FE-5680A and FE-5650A oscillators.  I can't say what
> slowly is, but this guy was good at killing them.  If I get some time I may
> try to repeat the results.
> My advice was to set the supply at 15V and just turn it off and on.  I have
> not heard from him since.
> If anyone out there has a 5680A or 5650A that does not lock, the code issue
> is very likely the problem.  I have seen several 5680 units as well as a
> few 5650 units with this problem.  The good news is that they can be
> fixed.  I would happily do this for any time-nut that has one if return
> postage is included with the unit.  The bad news is that we don't know the
> nature of the code problem that trashes the software (stack overflow, error
> handling routine, etc.) so units can only be restored to their original
> condition that still has the bug in the code.
> Otherwise, the 5650 and 5680 are great values to get rubidium performance
> at very reasonable prices.  I have 1000's of hours on them and 100's of
> power cycles, with a lot of serial port use, so if treated correctly they
> are reliable units.
> Regards,
> Skip Withrow
> RDR Electronics, Inc.
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