CALIBRATION AND TROUBLESHOOTING
Calibration Overview
124 LDC-3700 Series
CHAPTER 5
1 With the output off, connect a 1 Ω, 20 W resistor across the TEC output terminals (TE
Module + and TE Module −).
2 Connect a calibrated DMM across the load resistor. You will be calculating TE current in
the following manner using Ohm’s Law:
I = E / R
where E is the accurately measured voltage across the resistor, and R is the accurately
measured load resistance. I is the calculated current in Amps. (A 4−point probe
resistance measurement is recommended.)
3 The TEC output must be off in order to enter the I
TE
calibration mode. Enter the
"TEC:OUTPUT OFF" command.
4 Enter the TEC:CAL:ITE command to place the controller in TEC Current Calibration
mode.
The TEC display indicates a small current in Amps as the temperature controller
calibrates itself for a zero current level. After 20 seconds, the TEC controller drives the
output to 2.000 amps. Once stable, the temperature controller is ready to enter the actual
TE current value.
5 Enter the TE current value using the TEC:ITE <nrf value> command. The (absolute
value of the) actual ITE value is the <nrf value>.
The controller drives the TE output current to the negative value of −2.000 Amps.
6 Repeat step 5 for the negative polarity of the TEC output current.
After the negative polarity value of the TEC output is entered, the controller automatically
calibrates its current limits and set points, indicated by the flashing TE Current Limit
indicator. The controller then returns to the state before calibration.
TEC Voltage Calibration
The following procedure is for calibrating the TEC voltage measurement. This procedure calibrates
the positive and negative voltages in one procedure.
Note: The TEC Voltage calibration may only be performed remotely.
1 With the output off, connect a 50 Ω, 5 W resistor across the TEC output terminals (TE
Module + and TE Module −).
2 Connect a calibrated DMM across the load resistor. Enter the "TEC:ITE 0" command to
set the TEC current to zero for the start of this procedure.
3 Enter the "TEC:CAL:V" command to place the Controller in its TEC Voltage Calibration
mode The TEC display will indicate a current of about −0.12 Amps so that the TEC
voltage will be about −6.00 volts.
4 When the Controller is ready for the actual voltage value to be entered, a remote query of
"TEC:CAL:V?" will return a response of "1". Allow a few seconds for the TEC current to
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