Step 1: Layered troubleshooting failures
First, inspect the fundamental wiring: Confirm that the thermocouple calibration number precisely matches the thermostat setting, that the compensation wires are not inverted or mismatched, and that the terminals are not oxidised or loose. Eliminate false failures due to human wiring faults.
To verify hardware status, use a multimeter to measure thermocouple circuit resistance and insulation resistance. Confirm that insulation resistance is ≥1MΩ. Check for hardware issues like hidden cold solder joints on thermocouple wires, worn insulation layer grounding, and isolator malfunctions.
Third, ensure installation and environmental compliance. Check that the thermocouple is inserted into the hot runner at the proper depth and that the sensor end is entirely in contact with the temperature measurement site. Check that the signal shielding system is appropriately grounded to avoid calibration errors caused by signal drift and oscillations.
Step 2: Targeted rectification
To fix a temperature measurement deviation of less than ±3℃, change the Husky thermostat's temperature offset compensation parameters and re-run PID self-tuning.
Hardware Defect Rectification: If the inspection reveals thermocouple wire contamination or excessive stress that causes material deterioration, the precious metal thermocouple can be cleaned and annealed to remove tension. If the thermocouple is old and damaged, replace it with a qualified new thermocouple and recalibrate.
Interference Issue Resolution: If signal drift is caused by improper grounding or electromagnetic interference, disconnect the signal line to ground for discharge, re-standardize the shielding grounding, and replace the faulty signal isolator as needed.
Step 3: Post-Rectification Recalibration and Closed-Loop Acceptance After rectification, utilise a high-precision dry block furnace and a multifunctional process calibrator to generate standard temperature/millivolt signals. Conduct comparative testing at 3-5 common production temperature points to ensure a temperature measurement inaccuracy of ≤±1℃ over the full range.
Run at a constant temperature for 30 minutes to ensure the temperature display fluctuation range is ≤±1℃ and the measurement signal remains stable without drift. Re-record the calibration results. After confirming that the rectification is qualified, lock the calibration parameters to prevent unauthorised changes.
This closed-loop rectification procedure may entirely cure the issue of unqualified thermocouple calibration in Husky thermostats, restoring the hot runner temperature control system's accuracy to the appropriate level.
