How to Test Capacitors for Single-Phase Asynchronous Motors with a Multimeter
Use a screwdriver or wire to short-circuit and discharge the suspected faulty device at both ends, then remove it and measure it using the R × 10k or R × 1k gear. Connect the two probes to the two ends of the capacitor and make a judgment based on the swing of the probe.
(1) If the pointer swings significantly towards the zero position of the resistor first, and then slowly returns to the hundreds of kiloohms position, it indicates that the capacitor is intact.
(2) If the pointer does not move, it indicates that the capacitor has an open circuit fault.
(3) If the pointer does not return after reaching the zero position of the resistor, it indicates that the capacitor has been damaged due to internal breakdown.
(4) If the pointer reaches a smaller resistance on the dial and cannot return, it indicates that the capacitor has a large leakage current.
(5) If the pointer can swing and return, but the first swing is small, it indicates that the capacitor capacity has decreased.
(6) Turn the conversion switch of the multimeter to the R × 10k position and measure the resistance of the two leads of the capacitor to the housing with a probe. If the resistance is 0 Ω, it indicates that there has been a breakdown and short circuit between the capacitor electrode and its casing.
Common faults of multimeter
1. The pointer swings abnormally, with intermittent oscillation and resistance
Solution:
(1) Open the watch case and use tweezers and a screwdriver to adjust the mechanical swing part, making the pointer swing flexibly;
(2) Re weld the header wire, reconnect the shunt resistor when it is disconnected, and replace it with a shunt resistor of the same model when it burns out;
(3) Use tweezers to readjust the shape of the balance spring, making its outer ring smooth and evenly arranged;
(4
) Repair the supporting parts
2. No indication in resistance mode
(1) Reinstall the multimeter battery or replace it with a new one;
(2) Re weld the connection and adjust the center contact of the potentiometer to ensure good contact with the resistance wire;
(3) Clean the oil stains on the contact points and repair the contact pads. If the welding connection wire is disconnected, it needs to be re welded;
3. When the probe is short circuited, the pointer cannot be adjusted to zero or the pointer swings back and forth unstably
(1) Replace with a new battery of the same model;
(2) Replace the series resistor;
(3) Adjust the socket spring to ensure good contact, and remove the oxide layer on the probe plug and socket;
(4) Clean the switch contacts of the multimeter with alcohol and calibrate the contact distance between the moving contacts and the stationary contacts;
(5) Use tweezers to press down the moving contact piece in the middle of the zero potentiometer to ensure good contact with the static contact resistance wire;
4. Resistance range is not connected or the error is too large
(1) Replace the resistor with the same resistance and power;
(2) Wipe and repair poor contact areas with alcohol;
(3) Replace the shunt resistor of this gear;
(4) Replace with a new battery of the same model;
