How to Find Issues Using a Multimeter
How to use a line multimeter
Under live conditions, use AC voltage or DC voltage according to the situation! Use resistance gear to detect circuit paths and short circuits without points!
The multimeter has a beep stop, which means using two probes to measure the same wire. If there is a short circuit, there will be no response. If there is a circuit, there will be a beep sound. Sometimes, when the device itself is grounded poorly and the shell is live, the red probe of the multimeter can be placed on the black label of the shell to directly contact the ground. The strength of the shell leakage current can be measured by connecting it to the circuit in series for the rest of the work.
To check for circuit leakage, a megohmmeter (megger) should be used, as the voltage of the multimeter is lower (9V) and the voltage of the megohmmeter is higher (500V). Because the working voltage of the circuit is 220V, it is difficult to diagnose circuits with insignificant leakage. To use a digital meter to check for circuit leakage, you first need to cut off the power supply, discharge the circuit, and measure it with a resistance level of 2M. The normal display is 1 (infinite).
Measuring whether the circuit is in a connected state can be measured using a multimeter's ohm range. When measuring, it is necessary to select a range where the meter pointer is close to 0 ohms of deflection. If the circuit is in a circuit, one end (A end) of the circuit should be connected to a multimeter (red lead) at 100 ohms, and the black lead should be connected to the other end (B end) of the circuit to be measured. If the measured result is zero, it indicates that the circuit is connected, also known as a path. Only a path can current flow through the circuit; If the multimeter ohmmeter pointer at the A to B end of the circuit is not close to zero ohms, the circuit is already in an open circuit state, and disconnection is called an open circuit or an open circuit.
How to Use a Multimeter to Find Problems
A multimeter usually only uses two levels to check electrical faults, one is voltage level (including AC and DC voltage levels) and the other is ohms.
If the device is no longer working, the first thing you think about is whether the device voltage is normal, you need to use the voltage range of a multimeter (choose AC voltage range or DC voltage range, depending on whether your device is AC or DC) to measure. If the control circuit or secondary circuit is disconnected, even if you are familiar with the schematic diagram, you need to use a voltage range to measure whether the voltage at a certain location is normal. If it is determined that the voltage at that location should not be present but rather present, and that it should be present but not present, it indicates that there is a disconnection or poor contact at that location. In order to better determine if there is a problem at this point, you also need to disconnect the power supply of the device. The ohm range of the multimeter determines whether the wire has indeed been disconnected at this point, in order to troubleshoot. Roughly speaking, it mainly depends on your familiarity with the equipment and accumulation of work experience
