General Operation and Maintenance of Digital Multimeters
Operation Steps
First, turn on the power of the digital multimeter, then select the measurement function according to the object: voltage, current, resistance or other parameters. Next, set the measuring range. If the parameter value is unknown, start from the maximum range and gradually switch to a smaller one. Before measurement, check whether the test probes are inserted into the correct jacks. Turn the range switch gently to avoid damaging the internal metal contacts. After use, set the function and range switch to the high‑voltage position.
2. Notes During Measurement with a Digital Multimeter
(1) For high resistance ranges, slight differences between digital multimeter readings and analog meter results are normal, caused by different internal test conditions.
(2) When measuring polarity‑related quantities, the displayed polarity corresponds to the probe connection. If no negative sign appears, the red probe is at the higher potential or the current inflow terminal. When a minus sign "−" is displayed, the red probe is at the lower potential or the current outflow terminal.
(3) The resistance and diode ranges differ from those of analog multimeters. On an analog meter, the internal power supply reverses polarity: the black probe is positive and the red probe is negative during resistance measurement. On a digital multimeter, the polarity is consistent - the red probe is positive and the black probe is negative, the same as in voltage and current modes. This design avoids confusion and is more user‑friendly than analog meters.
(4) For transistors with unknown polarity or pin arrangement, use the transistor hFE range and test different pin combinations repeatedly to identify each electrode correctly.
(5) CalibrationDigital multimeters require regular calibration. Use another multimeter of the same type or higher accuracy. Follow the sequence: calibrate DC ranges first, then AC ranges, and finally the capacitance range.
Digital multimeters commonly use a 9 V stacked battery, which usually needs replacement after several months of use. It is recommended to use a rechargeable 9 V battery instead. The nickel‑cadmium rechargeable battery model GP‑15F8K has the same size and appearance as a standard 9 V stacked battery.
