Adjustment, Repair and Component Replacement Methods for Multimeters
1. DC Current Section
The moving coil shall be installed squarely, and no ferromagnetic substances shall exist in the moving clearance. If any shunt resistor is burned out, replace it with one matching the rated value specified in the circuit diagram.
If the meter head has excessive sensitivity, demagnetization can be performed. Alternatively, the hairspring may be replaced or the damping coil may be rewound.
Clean the moving contacts of the range selector switch. Re-solder any joints with open or cold solder joints.
2. DC Voltage Section
Adjustment and repair of the DC voltage circuit can only be carried out after the current circuit has been properly calibrated. Perform adjustment range by range from low to high. Common resistors related to DC current shall not be readjusted.
3. AC Voltage Section
Adjustment and repair of the AC voltage section mainly focus on rectifier components, such as breakdown, damage or reduced reverse resistance of rectifier elements. When replacing, select diodes with characteristics close to the original ones. Similarly, any components related to DC current and DC voltage must not be readjusted.
4. Resistance Section
Replace the battery when its power is insufficient. Clean corroded contact points; if necessary, polish them gently with fine sandpaper and apply a thin layer of vaseline.
The electromagnetic clips shall maintain sufficient elasticity. Perform adjustment starting from the R×1 range up to the maximum range. Resistors associated with current and voltage circuits are not allowed to be readjusted.
