Amprobe AM-100 Digital-Multimeters - Manual (Page 5)

4
4) OPERATION
DC Voltage, AC Voltage, & Hz Frequency functions
Note:
1) AC 400.0mV range selection is by RANGE button manually, and is specified from
AC 10mV (AC 40mV for True RMS models AM-105 & AM-110) and up.
2) DC 400.0mV range is designed with 1000M
Ω high input impedance for least current
drain in measuring small signals, and can cope better with most commercially available
voltage output transducers and adapters. The non-zero display reading is normal when
the meter inputs are open circuit, which will not affect actual measurement accuracy.
Open input is actually a floating condition, which is not a zero-volt-input condition. The
meter will show zero or close to zero reading when the inputs are shorted.