1, first determine thermocouple connected to the instrument at the right, instrument index number is correctly set 2, with multi-function multimeter to measure the potential value of the thermocouple, in natural space with a mercury thermometer or other thermometer, as a comparison, the thermocouple conversion value of electric potential, and see how much temperature difference? Within the tolerance? More than. Want to see the super? Note: the temperature measurement is only for reference, because the temperature error and there are many reasons. Look at the site of error requirement is how much? If too much must send authority calibration test ( There is a difference between calibration and verification) 3, check the material of thermocouple with compensation lead material match? 4, separate check: first check the problem of thermocouple, instrument, then check compensation conductor problem. 5, the impact of temperature thermocouple is allowed to: whether the welding is firm, is welding in what way? Welding? Argon arc welding? Or what else? Presence of slag? Air hole? For cleaning? Whether for annealing. Affect temperature are not allowed to be the reason and, of course: is there a correct installation position? Insert depth standard? Thermocouple type selection is correct? The compensation of the thermocouple wires is correct? Compensation conductor model match? Thermocouple wire are correct? To replace thermocouple first, then the instrument under the conditions allow, thermocouple problem is sure? Or instrument problem? Such as choice of the same type thermocouple no problem, or thermocouple is no problem, there is something wrong with the meter is in instrumentation, note: six general instrument will not have a problem, the whether is negative, confirm the correct connection.