how to determine (test) if the dc voltage range (dcv) of a multimeter is functional?
When testing, the first step is to find the testing source. As we are qualitative with a little quantitative measurement, there are many available testing sources. Household testing sources include 1.5V alkaline/carbon batteries (No. 1, No. 5/AA, No. 7/AAA), 1.2V rechargeable batteries, mobile phone chargers, power adapters, and so on. When testing, turn the multimeter to the desired DC voltage range, insert the probes according to the instructions, connect the testing source, and read the reading on the LCD. As long as the measured value is around the nominal voltage, it is sufficient.
PS: To repeat, we are using qualitative and a little quantitative measurement, so we can use these sources because their voltage is not very stable. For example, for a 1.5V battery, a new battery may reach over 1.6V, while an old battery may only have a voltage of a few tenths of a volt.
How to determine the quality of DC current range (DCA)?
If there is a known current source, input it directly in the current mode. If not, it's okay. Just input the voltage in the current mode. If it goes out to 1, shift it to the lower range mode until a valid value appears. Please also pay attention to the following points:
A, Please do not input too high voltage to avoid damaging the instrument due to excessive current. Common sources that can be input include regular batteries such as No.5, No.7, etc;
B, When measuring the current of the input voltage, due to the small resistance (load) of the internal resistance of the instrument, if the input is too long, it will damage the source. Therefore, a single input should not exceed 5 seconds as much as possible;
C, The relationship between different high and low ranges, adjacent ranges, is generally 10 times.
