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Sequence Number, Fault Phenomenon, Possible Causes, Troubleshooting Methods: 1. Power is turned on – the power switch is not activated, but the heating voltage meter shows a reading and cannot be adjusted. 1. The terminal is loose or has poor contact. 2. The heating wire is broken or there is poor contact at the ceramic joint. 3. The solid-state voltage regulator inside the controller is damaged. 4. Heat the fuse damage ring. 1. Tighten the terminal posts. 2. Use a multimeter to measure whether there is any resistance at the terminals (with the power supply turned off). 3. Replace the solid-state voltage regulator according to the model. 4. Replace the fuse. 2. The power switch is turned on, but there is no indication at all. 1. The main power fuse is damaged. 2. Poor internal contact at the power switch. 3. The power supply connection is incorrect. 1. Replace the fuse. 2. Replace the twist switch. 3. Use a meter to measure the voltage of the power supply being used and make corrections accordingly. 3. No temperature display or negative values appear. 1. The wiring of the thermocouple has come loose and is in contact with each other, which can lead to poor connection when it is plugged into the controller socket. 2. The thermocouple is damaged and the wire is broken. 3. The thermometer is damaged. 1. Open the thermocouple connector, re-solder the wire ends or swap the wiring positions, and reinsert the thermocouple socket tightly. 2. Replace the thermocouple. 3. Replace the thermometer. 4. Turn on the mixing potentiometer to adjust the voltage, but the motor does not rotate. 1. The mixing fuse is damaged. 2. Thyristor damaged. 3. The motor wiring connector has a loose connection. 4. The potentiometer switch on the panel is damaged. 5. There are damaged components in the overall circuit board. 1. Replace the fuse. 2. Use a multimeter set to RX1 to measure the resistance between the cathode and the control gate of the thyristor. The forward resistance should be 30–40 Ω, while the reverse resistance should be 60–80 Ω. Then, use a circuit to determine whether the performance of the thyristor has deteriorated. If the bulb lights up immediately upon connection, and continues to glow even after disconnecting the control gate, this indicates that the thyristor is undamaged. 3. Use a multimeter to make measurements according to the circuit diagram, identify the fault, and correct it. 4. Remove the potentiometer, use a meter to touch its two terminals and adjust slowly to check for any disconnections; if none are found, replace it. 5. Start by checking the supply voltage of the circuit; see whether the transformer outputs 55V and 20V voltages. Then, check Q1, Q2, BT33, A940, the 10K potentiometer, the pulse transformer, etc., in sequence. 5. When the stirring switch is turned on, the fuse burns out immediately; or after replacing the fuse, it burns out right away. 1. Short circuit in the motor wiring. 2. A diode in the thyristor wiring board has burned out. 3. Silicon controlled rectifier breakdown. 4. Short circuit in the motor excitation coil. 1. Correct the wiring. 2. Use a multimeter to measure the diode: the forward resistance should be between 15-20Ω, while the reverse resistance should be infinite. 3. Use the 10K range of Table 10 to measure the resistance between 3CTA and K; it should be infinite, otherwise it is damaged. 4. Normal resistance values after replacing the motor: 123W (1.9K), 185W (1.5K), 355W (1.5K). 6. The rotational speed operates normally, but the stirring speed is not displayed. 1. Check whether the speed detection plug wires and the Hall element are damaged. 2. The speed measurement sleeve at the top of the magnetic stirrer has shifted. 3. Reverse the position of the Hall element during maintenance. 4. The speed-measuring magnet inside the device has fallen off or lost its magnetism. 1. Use a multimeter to check whether there is poor contact or welding failure in the speed measurement wires. 2. Gently move the speed measurement sleeve up, down, left, and right; once the rotation speed stabilizes, tighten it. 3. Hall elements have N and S poles, and this controller uses the N pole for speed measurement. 4. The speed-measuring magnet is sensitive to hydrogen; if it is damaged by hydrogen, please contact the manufacturer. 7. The temperature cannot be controlled when in automatic control mode. 1. The solid-state voltage regulator is damaged. 1. Replace the solid-state voltage regulator with the original model