How to detect fault in a thermistor?

(1) ​​Visual Inspection​​

First, observe the thermistor's exterior. Ensure the potentiometer or thermistor has ​​clear markings​​, with ​​no corrosion​​ on solder tabs or pins. The rotating shaft should turn ​​smoothly​​ with ​​appropriate tightness​​, and there should be ​​no mechanical noise or jitter​​ during rotation.

(2) ​​Check for Loose Connections​​

Gently shake the solder tabs or pins of the potentiometer or thermistor. There should be ​​no looseness​​ detected.

(3) ​​Resistance Measurement​​

• Set the multimeter to the appropriate ​​resistance range​​ and perform ​​ohm zero adjustment​​.
• Connect the multimeter probes (ignoring polarity) to the thermistor's two terminals. Measure the actual resistance value.
• Compare the measured value with the thermistor's ​​nominal value​​:
  • If the pointer ​​does not move​​, the internal resistor is ​​open-circuited​​ (damaged).
  • A significant deviation from the nominal value indicates a fault.

(4) ​​Contact Point Test​​

• Connect one probe to the ​​center pin​​ (linked to the internal moving contact) and the other to any other terminal.
• Slowly rotate the shaft. The meter needle should move ​​smoothly and correspondingly​​.
• ​​Jumping or dropping​​ of the needle suggests ​​poor contact​​ between the moving contact and resistor element.