Originally posted by Aaron
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.99
So in really bad cases, it overwhelms the balance circuit's ability. This is when the separate Earth connection to the instrument's chassis helps considerably, as this noise riding on the wall plug's third wire ground is then shunted to Earth and the instrument does not see it.
. This is usually done as sort of a "double-check" for safety, and is again because of the insurance. But other times, the isolation tranny's are used because the power is so darn noisy in that area of the hospital (often because there is an X-Ray machine next door or something). So even these Earth grounds don't always do the trick in extreme noise situations
It ain't easy.





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