Fault analysis and elimination of intelligent muffle furnace

A: Open thermocouple: turn off the power supply and open the back cover of the muffle furnace:

(1) Check whether the nut connecting the terminal post of the thermocouple and the lead wire of the thermocouple is tightened, and ensure that the two are in good contact.

(2) Check whether the thermocouple sensor itself has an open circuit condition. (It can be tested with a meter, such as a multimeter)

(3) Check whether the connectors, wiring terminals, and adapters between the end leads of the thermocouple and the circuit board are open or virtual open. Sometimes it can be restored to normal after plugging and unplugging it once again. This is due to the installation process or a layer of oxide layer that appears when the terminal is at a high temperature for a long time.

(4) Caused by strong interference signals, this kind of situation is rare.

B: Thermocouple connection reversed: Turn off the power supply, open the back cover of the muffle furnace, and check whether the polarity of the thermocouple end and the polarity of the thermocouple input port of the controller are the same after the line is connected. (Available visual inspection method and instrument test method)

C: Communication interruption: Check whether the external line interface of the controller is disconnected or has poor contact (such as the connection of the nine-pin serial port, aviation plug, etc.), and ensure that the connection is reliable and the contact is good.

D: The touch function is invalid:

(1) Check whether the display cable is in good contact. Open the controller shell and check whether the display cable between the display screen and the control board is aged or has poor contact. Sometimes the interface at both ends of the display cable can be restored to normal after plugging and unplugging it once.

(2) Display cable problems or display problems. Contact the manufacturer for replacement.

E: No display on the display (black screen):

(1) Check whether the power supply interface of the controller is off or loose.

(2) Observe whether the power indicator light inside the controller is on, if it is on, check whether the display cable is faulty; if the internal indicator light is off (the interior is dark), troubleshoot it according to the following methods.

(3) Check whether there is a short circuit inside the controller. Disconnect the serial port cable on the back of the controller, use a meter to test whether there is a short circuit between the 6 pins and 9 pins of the serial port. Make sure that there is no internal short circuit (that is, there is no short circuit between the 6 pins and 9 pins of the serial port on the back of the controller. Short-circuit phenomenon).

(4) Check whether the switching power supply has a DC 5V output. Disconnect the serial port cable on the back of the controller, turn on the power, and use a meter to test whether the switching power supply has a DC 5V output, or visually check whether the indicator light next to the switching power supply is on. Make sure that the output voltage of the switching power supply is normal.

(5) Check whether the power supply circuit of the controller is broken (instrument test).

(6) Check whether the internal connector of the controller is off or loose.

(7) Comprehensive circuit failure, contact the manufacturer to remove or replace it.

F: Fuzzy or severely abnormal colors appear on the display:

(2) Display cable problems or display problems. Contact the manufacturer for replacement.

G: The controller restarts repeatedly: check whether the 5V DC output of the switching power supply is stable (change within ±0.2V). Generally, it is caused by a large jump range of the output voltage of the power supply, instability, or damage to internal components.

H: Switching power supply has no DC5V output (the indicator light is off):

(1) Ensure that the load is not short-circuited. Disconnect the serial port cable on the back of the controller, use a meter to test whether there is a short circuit between the 6 pins and 9 pins of the serial port. Make sure that there is no internal short circuit (that is, there is no short circuit between the 6 pins and 9 pins of the serial port on the back of the controller. Short-circuit phenomenon).

(2) Ensure that the input terminal has AC (170V～250)V, 50Hz voltage input.

(3) The switching power supply itself is damaged. Contact the manufacturer to remove or replace.

I: The furnace temperature rises below the set temperature for a long time at the beginning of the experiment:

(1) The furnace wire is open. Check whether the furnace wire is open or the load power is not enough (a set of furnace wires is broken). The resistance of the furnace wire can be tested with an instrument, which is normally about 10-15 ohms.

(2) The solid state relay is burned out or damaged. Check whether the solid state relay is damaged or the control wiring is not in good contact.

(3) The voltage is too low.

J: No heating or no heating

(1) The furnace wire is open. Check whether the furnace wire is open, open the back cover of the muffle furnace, and test the resistance of the furnace wire with a meter. Normally, it is about 10-15 ohms. (Check if the junction of the terminals is in reliable contact)

(2) The solid state relay is burned out or damaged. Check whether the solid state relay is damaged or the control wiring is not in good contact.

(3) The thermocouple has an open circuit. Check if there is an open circuit, then restart the device after power off

(4) The control circuit is faulty. Check whether the serial port data line is plugged in reliably and firmly, and check whether the solid state relay control line interface is in reliable contact

(5) Controller problem. Contact the manufacturer.

K: Enclosure is charged:

(1) Check whether the power supply line is damaged or has a wire drawing connection with the case.

(2) Check whether the ground wire of the power supply is in reliable contact or is missing.

(3) Dry air and static electricity.