Author Topic: One battery fairy tale (repair of nV-meter FE).  (Read 974 times)

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Offline TiN

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One battery fairy tale (repair of nV-meter FE).
« on: August 04, 2016, 04:58:37 pm »
Almost a year ago I traded one of my 2001's to 182-M nV-meter.
Used it for few experiments back then and had it sitting on the bench unpowered since then. Today got it back online, but was greeted by some jumping values on magnitude of few tens of mV.
What happen?

Perhaps 9V battery went poo? Yes this 182-M has battery inside, powering front end amplifier even when meter is OFF.  :-DMM

Three screws, cover removed...



Woohoo, self-destruction mode activated  :scared:

Replaced it with new fresh 9V, put meter cover back in, turn on...



All fine again. Will get some datalogs going, as 3458A is pretty useless for measuring 200 microVolts here..  ;)

Destroyed bat still reads 7.5V btw  :P

End of story. Don't forget to replace those batteries inside instruments.  :-BROKE
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Offline fire219

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Re: One battery fairy tale (repair of nV-meter FE).
« Reply #1 on: August 06, 2016, 12:44:37 am »
Now that's what I call bad design...
 

Offline blueskull

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Re: One battery fairy tale (repair of nV-meter FE).
« Reply #2 on: August 06, 2016, 04:06:10 am »
Destroyed bat still reads 7.5V btw  :P

One failure mode of Alkaline batteries is increased internal resistance while maintaining quite a high open circuit voltage.
 


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