E-Meters can go out of trim during a session because of temperature changes.
Thus even if the meter is properly calibrated and reads at 2.0 with a 5,000 ohm resistor across the leads and 3.0 with 12,500 ohms, by the end of the session a pc can be apparently reading below 2.0 because the meter is off trim.
The following meter procedure is therefore to be followed AT THE END OF EACH SESSION (AFTER GIVING “THAT’S IT”):
1. DON’T MOVE THE TRIM KNOB
2. PULL OUT THE JACK PLUG
3. MOVE THE TA UNTIL THE NEEDLE IS ON “SET” AT THE SENSITIVITY YOU WERE USING IN THE SESSION
4. RECORD THE TA POSITION AT THE BOTTOM OF THE AUDITOR’S REPORT FORM AS: “TRIM CHECK — TA = …”
5. IF YOUR METER IS KNOWN TO BE OUT OF CALIBRATION (as in Para 2 above) RECORD ALSO: “Calibration error — on meter = 2.0 actual” at the bottom of the form.