Minco CT124, Instruction Manual, Page: 22 / 26

TROUBLESHOOTING
CALIBRATION INSTRUCTIONS
The CT124 is factory calibrated and only requires recalibration if the RTD board is replaced, the non-
volatile RAM fails, or long-term high accuracy is required.
Annual calibration is recommended to
maintain the CT124’s specified accuracy for many years.
Calibration is very simple if you use a Minco AC758 RTD Simulator. Alternatively, you may use 9
individual precision resistors, of which 8 are used to simultaneously simulate each input RTD at 0°C
(32°F) and the other is used to simulate 195°C (383°F).
1. Enter the programming mode and step through the program until the display reads
(see page 12).
2. Press and together to change the display to . Press twice to exit
the program mode. The display should now read (Factory Calibration).
3. If you do not have an AC758 RTD simulator, leave the calibration mode now by pressing .
Otherwise, press or so the display reads (User Calibration).
4. Press . The display should now read .
5. Unplug the RTD connector board from the rear of the CT124 and replace it with the AC758. Be
sure the 2-letter code of the RTD type is correct; e.g. use an AC758PD RTD Simulator with a
CT124PD Controller (see model number coding on page 23).
If you do not have an AC758, connect 8 resistors of the proper value to simulate 0°C into the
terminal blocks. Make sure you provide a 3-lead connection.
6. Set the Switch on the AC758 to 0°C and press . The CT124 will calibrate itself to 0°C and
then display .
7. Set the switch on the AC758 to 195°C (or install a resistor into the zone 1 RTD position that
simulates the RTD at 195°C) and press . The CT124 will calibrate itself to 195°C and then
display (Continue).
8. Remove the AC758 and reinstall the RTD connector board.
9. Press . Calibration is complete when the display returns to zone temperature. If the display
goes back to reading , something went wrong during calibration. Try again, starting
at step 3.
Minco Products, Inc. CT124 Instruction Manual
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