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

[paul swed]

The units were never intended for a slow ramp
I assume it runs into a meta stable condition
Neither on or off and then corruption
Glad you're can repair them

On Tuesday, June 7, 2016, Bob Camp <kb8tq at n1k.org> wrote:

> Hi
>
> 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.
>
> Bob
>
>
> > On Jun 7, 2016, at 5:22 PM, Skip Withrow <skip.withrow at gmail.com
> <javascript:;>> 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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