ELVIS II Voltage Increase Problem

[Star_Man]

Several years ago we purchase 14 ELVIS II systems.  Very quickly we noticed several of them would build up a voltage on all of the AI lines.  We found that most of the time this was not a problem.  We now are trying to send microphone voltages into the AI ports and this voltage increase does not allow the microphones to work correctly.  Does anyone know of this problem with the ELVIS II systems?

[santo_13]

In general, it is expected to see unexpected voltages at AI when unterminated or open since the input is high impedance.

https://knowledge.ni.com/KnowledgeArticleDetails?id=kA00Z000000P6TeSAK

It is a problem only when you apply a known signal at AI but you read incorrectly.

Read this article - 

https://knowledge.ni.com/KnowledgeArticleDetails?id=kA00Z000000P9mKSAS&l=en-US

Tell us more about your microphone and how you hook them up, instrument settings, range, etc.,