Common faults and solutions of muffle furnace

Common faults and solutions of muffle furnace
1. Thermocouple open circuit: Turn off the power supply and open the rear cover of the muffle furnace.
(1) Check whether the nuts connecting the thermocouple terminal posts and thermocouple leads are tightened to ensure good contact between the two.
(2) Check whether the thermocouple sensor itself has an open circuit condition. (Can be tested with an instrument, such as a multimeter)
(3) Check whether the connectors, terminals, adapters, etc. between the thermocouple end leads and the circuit board are open or not. Sometimes it can be restored to normal after being plugged and unplugged once again, which is caused by the installation process or a layer of oxide layer that occurs when the terminal is exposed to high temperature for a long time.
(4) Caused by strong interference signals, which is rare.
2. Thermocouple reversed connection:
Turn off the power supply, open the rear cover of the muffle furnace, and check whether the polarity of the thermocouple end and the polarity of the controller thermocouple input port are consistent after wiring. (Visual and instrument testing methods are available)
3. Communication interruption:
Check whether the line interface outside the controller has fallen off or has poor contact (such as 9-pin serial port, aviation plug, etc.), and ensure reliable connection and good contact.
4. Invalid touch function:
(1) Check whether the display cable is in good contact. Open the controller housing and inspect the display cable between the display screen and the control board for aging or poor contact. Sometimes, by reinserting and unplugging the connectors at both ends of the display cable, it can be restored to normal.
(2) Display cabling issues or display issues. Replace with the manufacturer.
5. No display on the display screen (black screen):
(1) Check whether the power supply interface of the controller is detached or loose.
(2) Observe whether the power indicator inside the controller is lit, and if it is lit, check whether the display cable is faulty; If the internal indicator light does not light up (the interior is dark), troubleshoot it as follows.
(3) Detect whether there is a short circuit inside the controller. Disconnect the serial port connecting wire at the rear of the controller, and use a meter to test whether there is a short circuit between pins 6 and 9 of the serial port. Ensure that there is no internal short circuit (that is, there is no short circuit between pins 6 and 9 of the serial port at the rear of the controller).
(4) Check whether the switching power supply has a DC 5V output. Disconnect the serial port connection line at the rear of the controller, turn on the power supply, and use a meter to test whether the switching power supply has a DC 5V output, or visually inspect whether the indicator light next to the switching power supply is lit. Ensure that the output voltage of the switching power supply is normal.
(5) Check whether the power supply line of the controller is broken (instrument test).
(6) Check whether the internal connector of the controller falls off or is loose.
(7) Comprehensive circuit failure, troubleshoot or replace with the manufacturer.
6. The display screen appears blurred or severely abnormal color:
(1) Check whether the display cable is in good contact. Open the controller housing and inspect the display cable between the display screen and the control board for aging or poor contact. Sometimes, by reinserting and unplugging the connectors at both ends of the display cable, it can be restored to normal.
(2) Display cabling issues or display issues. Replace with the manufacturer.
7. Repeated controller restart:
Check whether the DC 5V output of the switching power supply is stable (varies within ± 0.2V). Generally, it is caused by a large jump range, instability, or damage to internal components of the power supply output voltage.
8. Switched power supply without DC5V output (indicator light not lit):
(1) Ensure that the load is free of short circuits. Disconnect the serial port connecting wire at the rear of the controller, and use a meter to test whether there is a short circuit between pins 6 and 9 of the serial port. Ensure that there is no internal short circuit (that is, there is no short circuit between pins 6 and 9 of the serial port at the rear of the controller).
(2) Ensure that the input terminal has an AC (170V~250) V, 50Hz voltage input.
(3) The switching power supply itself is damaged. Eliminate or replace with the manufacturer.
9. At the beginning of the experiment, the furnace temperature did not rise to the set temperature for a long time:
(1) The furnace wire is open. Detect whether the furnace wire is open circuit or the load power is insufficient (a group of furnace wires are broken). An instrument can be used to test the resistance of the furnace wire, which is normally about 10-15 ohms.
(2) The solid-state relay is burnt out or damaged. Check whether the solid-state relay is damaged or the control wiring is in poor contact.
(3) The voltage is too low.
10. No heating or no heating
(1) The furnace wire is open. Check whether the furnace wire is open, open the rear cover of the muffle furnace, and use a meter to test the resistance value of the furnace wire, which is normally about 10-15 ohms. (Check whether the junction of the terminal posts is reliably contacted)
(2) The solid-state relay is burnt out or damaged. Check whether the solid-state relay is damaged or the control wiring is in poor contact.
(3) The thermocouple has an open circuit. Check for an open circuit, then power down and restart the device.
(4) The control circuit is faulty. Check whether the serial port data line is reliably and firmly connected, and check whether the interface of the solid-state relay control line is reliably contacted.
(5) Controller issues.
11. Case electrification:
(1) Check whether the power supply line is damaged or connected to the chassis by wire drawing.
(2) Check whether the power supply ground wire is reliably contacted or missing.
(3) Air drying, caused by static electricity.