[time-nuts] PRS10

[Mike Cook]

> Le 11 août 2016 à 12:15, Martyn Smith <martyn at ptsyst.com> a écrit :
> 
> Hello,
> 
> I have a strange fault on a PRS10.  Wondered if anyone had seen it.
> 
> I am running a PRS10 and at the same time monitoring its FC (the frequency control value) and Status byte data values.
> 
> So normally, the Status shows are all zeros, except 2nd from last is a 1, showing the unit is not receiving any 1 pps signals.
> 
> What happens is the FC value suddenly jumps from its current setting (-150 for example) to zero, for no apparent reason.  

if -150 is really what you saw, then it is out of bounds as the two values returned by fc? are both +ve.
if they go to zero, check the eeprom values
fc!?
58,5485,1534,1434      for example
If they are reasonable then possible the eeprom is not being read correctly after reset. 

> 
> Then a short while later, the Rubidium's status bytles go crazy, mostly to FF.

This indicates a microprocessor reset .  After a power cycle you can see:
st? 
255,255,255,243,162,255      ie most  FF
when you read again you get the current values
st?
0,0,0,0,130,0         for example
then if you reset the microprocessor
RS 1
PRS_10
st?
255,255,255,243,162,255      back to the initial state 
st?
0,0,0,0,130,0

So it looks like you are getting resets. Possibly from brown outs. Maybe a low power condition at reset prevents eprom data being read correctly.

Are the affected RBs on the same power supplies? 


> 
> Then the rubidium goes back to the previous correct state (all zeros) but the FC value is now zero.
> 
> If you do connect a 1 pps, you get the same fault.
> 
> The confusing thing is I've suddenly seen this on 3 or 4 different rubidium's.  Some brand new, some five years old. 
> 
> Obviously suspect the power supply, but it doesn't seem to be that.
> 
> Best Regards
> 
> Martyn 
> 
> 
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