Common fault repair method for instrument input parts - News - Global IC Trade Starts Here Free Join

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The meter can't work normally. Everyone usually thinks it is a problem with the meter. It won't study which part or detail of it. When repairing, blindly disassemble the meter and find that you have done something wrong, so that whether it is repairing work or repair. Workers are not a good thing, and often the troubles brought us will be more. After the meter is properly wired according to the wiring diagram, the meter first displays the thermocouple index number of the meter, then displays the range of the meter range, and then measures the set temperature of the digital tube in the lower row of the meter. The digital tube on the meter displays the measured temperature. If the digital tube on the meter displays the temperature of the heating element and displays the status of “OVER”, “0000” or “000”, indicating that the input part of the meter is faulty, the following test should be performed: 1. Thermocouple from the meter thermocouple Remove the input and short-circuit the meter thermocouple input with any wire. When the power is on, the display value of the digital tube on the meter is about room temperature, indicating that the internal connection of the thermocouple is open, and the same type of thermocouple should be replaced. If it is still the above situation, it means that the instrument is damaged during the transportation process, and the instrument should be exchanged. 2. Remove the thermocouple of the above faulty instrument and replace it with the thermocouple connected to the same type of indexing instrument on the side of the normal operation. After the power is turned on, the digital tube on the original faulty meter displays the temperature of the heating element, indicating the thermocouple. The internal wiring is open and the same type of thermocouple is replaced. If it is still the above, it means that the instrument is damaged during the transportation process and the instrument should be replaced. 3. Remove the faulty thermocouple from the meter, use a multimeter to measure the ohms (R)*1 file, and use the multimeter to measure the two ends of the thermocouple. If the resistance value displayed on the multimeter is large, The thermocouple is internally connected to open circuit and replaced with the same type of thermocouple. Otherwise, there is a certain resistance value, indicating that there is a problem at the input of the meter, and the meter should be replaced. 4. According to the wiring diagram of the instrument, the wiring is correct. If the instrument is powered on, the digital tube on the meter shows a negative value, which indicates that the thermocouple “+” and “—” connected to the instrument are connected incorrectly. Just re-change it. 5. Wiring correct When the instrument is running, the temperature displayed on the digital tube on the meter is 30oC~60oC from the actual measured temperature. Even the difference is even larger, indicating that the meter's index number and the thermocouple's index number are wrong. According to the correspondence between the temperature (oC) and the millivolt (MV) value of the thermocouple with thermocouple indexing numbers B, S, K, E, etc., the millivolt value (MV) generated in the case of the same temperature (oC) The B index is the smallest, the S index number is small, the K index number is larger, and the E index number is the largest. According to this principle, the discriminant is determined.