[time-nuts] Troubleshooting Fluke PM6681

Magnus Danielson magnus at rubidium.dyndns.org
Sun Aug 16 15:16:22 EDT 2015


I checked with a former Pendulum employee, and free off memory, he 
recommend trimming up the 100 MHz until Error 2 does not show. Sensing 
it directly can be difficult, FET-probe essentially mandatory. 
Indirectly a 10 MHz is possible. A problem is that trimming with the 
hood off causes a different thermal setup than when the hood is on. If 
you dare, make a hole in the hood so that you can trim it with the hood 
on, that is what they did.

CMOS backup battery eventually fails, and then you need to replace it 
and re-calibrate it. I have the details jotted down, but it seems that 
this is not your issue.


On 08/16/2015 12:20 PM, Ole Petter Ronningen wrote:
> Hello.
> I have a Fluke PM6681 that has issues. When I got it, it gave results all
> over the place, but after adjusting the 100Mhz multiplier-chain, it seems
> to be much better; at least I get std.deviationwell within spec using a
> split pulse to input A and B, 100 samples. I'd like to get it
> professionally calibrated, but I don't want to send it in with known issues
> - the cost of calibration will not be refunded if the instrument can not be
> calibrated, and I believe it is no longer repairable.
> So, the issue is that it fails the ASIC test (test 6), with err 2.The
> service-guide lists a number of signals to be checked in test-mode, but I
> am not able to see any of them. Since the counter seems to function, I can
> only conclude that the signals are not present due to this error.. (Or that
> I am mistreading the guide and looking in the wrong place, probably at
> least as likely..)
> Anyway, I cant seem to find a description of this particular error, does
> anyone know what it means?
> Thanks,
> Ole
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