No temperature display is one of the most intuitive and common sudden faults of hot runner thermocouples, which directly causes failure of heating control and forced halt of production lines. Mastering fast hierarchical troubleshooting steps can locate fault points efficiently and restore normal operation in the shortest time.
First step, confirm power supply and controller status. Check whether the temperature control box is powered on normally, whether the corresponding temperature zone is started, and rule out equipment standby shutdown and parameter locking settings. If all zones have no display, the problem lies in total power supply or main control circuit; if only single zone has no reading, focus on independent circuit and thermocouple accessories of this zone.
Second step, inspect wiring circuit and terminal connection. Check whether thermocouple positive and negative wires fall off from terminals, whether wires are broken by stretching and extrusion, and whether terminal screws are severely loose or oxidized leading to complete open circuit. Re-fix loose wiring and replace obviously damaged connecting wires temporarily for test.
Third step, judge whether the thermocouple itself is burnt out or broken. Disconnect the faulty thermocouple and replace it with a confirmed intact spare one for trial connection. If temperature display returns to normal immediately after replacement, it proves the original thermocouple has internal core wire fracture, probe burnout and other irreversible damages and needs direct replacement. If display is still blank after replacement, the fault exists in the controller internal signal receiving module or wiring loop.
Fourth step, eliminate short-circuit protection trigger reasons. Check whether thermocouple wires are in contact with hot runner metal shells causing metal short circuit, which will trigger controller automatic protection and shield temperature display. Isolate short-circuit contact positions and re-arrange wire layout reasonably.
After troubleshooting and recovery, conduct low-temperature gradual heating test to confirm stable temperature data without abnormal alarms. Standardized rapid inspection sequence can avoid blind disassembly, greatly shorten maintenance time and minimize production stop loss.
