Routine Operational Use and Maintenance for Digital Multimeters
(1) It is normal for the resistance test results to differ from the pointer meter test results for high impedance. This is mainly due to slightly different testing conditions.
(2) When testing physical quantities related to polarity, their polarity display corresponds to the probe. That is to say, when the polarity is not displayed, the red probe contact is the potential or current inflow end, and when the polarity is displayed as "-", the red probe contact is the potential low end or current outflow end.
(3) The resistance mode and diode mode are different from the pointer meter. When measuring resistance with a pointer meter, the red and black probes have opposite polarities to the test source, with the black probe being the positive terminal of the test source and the red probe being the negative terminal. However, the polarity of the digital meter is consistent with that of the test source, with the red probe indicating the positive terminal of the test source and the black probe indicating the negative terminal, which is consistent with the voltage and current levels. This avoids confusion and is superior to pointer tables.
(4) For transistors with unknown polarity or pin arrangement sequence, the electrodes of the transistor can be identified and determined through multiple pin changes in the HFE mode.
(5) Calibration.
The digital multimeter should be calibrated regularly, and a digital instrument of the same type or higher accuracy should be selected for calibration. The calibration should be carried out in the order of first calibrating the DC gear, then calibrating the AC gear, and finally calibrating the capacitor gear.
A digital multimeter often uses a 9V stacked battery, which usually needs to be replaced after a few months of use. Suggest purchasing a 9V rechargeable battery as a replacement. This nickel cadmium rechargeable battery model is GP-15F8K. It is exactly the same as a regular 9V stacked battery.
