Daily maintenance work:

① During use, pay attention to whether the power supply is normal. If the power indicator light is not on, first check whether the fuse is faulty and whether the power switch and light bulb are damaged.

② If the indication of the secondary meter is inaccurate or malfunctioning, the secondary meter itself should be checked for any faults first. The specific method is to first short-circuit the positive and negative input signals of the secondary meter. If the pointer points to the beginning of the scale, it indicates that there is no problem inside the meter. Then it can be determined that the fault is outside the meter, such as the thermocouple, compensating wire, and wiring terminal that may be at that point.

③ The irregular, high or low indication curve of the secondary meter may be caused by damage to the insulation sheath of the compensating wire, resulting in irregular short circuits of the positive and negative wires of the exposed metal part, or irregular contact with the protective bellows.

④ After the positive and negative input signal lines of the secondary meter are short circuited, the pointer does not return to zero, indicating that there is an internal problem with the secondary meter. You can first check if the bridge and road sections are normal. The specific method is as follows:

a. Measure the equivalent resistance of the bridge system with a meter to see if it is 167 Ω. Because the resistance of the upper branch is 250 Ω and the resistance of the lower branch is 500 Ω, the equivalent resistance is the parallel value of the upper and lower branch resistances.

b. If the bridge section is normal and the problem is not resolved, you can check the amplifier section and use a meter with R * 10 or R * 100 to apply the input signal to the amplifier input terminal. If the pointer of the secondary meter indicates in one direction, and then the multimeter probe is swapped and indicates in another direction, it indicates that the amplifier is not faulty. If an unbalanced signal is input to the amplifier and its output voltage is 7-15V, it can prove that the amplifier is working properly.

c. If the problem is still not resolved, you can also check whether the measured signal is normal. You can use the VJ-1 resistor to check if the indication on the secondary meter is consistent, in order to determine whether the signal line is grounded or short circuited.