The DC current error of the multimeter is large, and the nominal ranges are all positive errors of the same proportion

The DC current error of the multimeter is large, and the nominal ranges are all positive errors (negative errors) of the same proportion. Troubleshooting

Cause: For positive error: ① The resistance value in series with the meter becomes smaller; ② The sensitivity of the meter is too high.

repair:

① Adjust the adjustable resistor in series with the meter;

② The high sensitivity of the meter can be solved from three aspects: first, demagnetize the permanent magnet to weaken its magnetic field strength, thereby reducing the sensitivity of the meter; second, consider replacing a hairspring with a larger torque, which can also achieve the purpose of reducing the sensitivity of the meter; third, rewind the brake ring with slightly fewer turns than the original number of turns. The exact number of turns depends on the degree of high sensitivity of the meter.

If the errors are all negative errors of the same proportion, the analysis process is similar to that described above, but the idea is exactly the opposite.