TE Technology TC-720 - Manual (Page 64)

is in the cooling mode. Set this value to something greater than zero to restore the
controller’s capability of cooling.
LOW VOLTAGE: Verify the controller is receiving at least 12 V from the power supply. The controller will
shut off output power to protect the MOSFETs from damage if the input voltage drops
below 11.2 V.
OVER CURRENT: Verify that the over-current level is set to an appropriate amount that is at least greater
than the expected current draw of the thermoelectric device used with the controller.
Check that a sufficient number of over-current restart attempts has been set.
OUTPUT ON/OFF: Verify that the controller has been set to turn on output power. You should also verify that
the power supply is capable of providing the expected amount of current for the
thermoelectric device at the voltage supplied by the power supply. If the power supply
cannot provide sufficient current, it may be in an over-current condition.
ALARM: Verify that there are no alarm conditions and that the temperatures which trigger an
alarm condition are set correctly. If you are certain no alarm condition exists, click the
SEND LATCH CLEAR button.
INTERLOCK: Verify that the interlock is not forcing the output to off.
INCORRECT POWER SUPPLY: Using a power supply with a current output capability that is too low for the load will
cause the power supply to shut down. Verify with a voltmeter that the power supply is
not repeatedly shutting down and then restarting. The green LED on the controller may
still flash if the controller intermittently receives sufficient operating voltage.
CONTROLLER IN RAMP SOAK MODE: From the keypad, select RUN PROGRAM > NO (TC-720 only), or from the GUI
select PID control mode.
SYSTEM TEMPERATURE INCREASES WHEN COOLING EXPECTED:
INSUFFICIENT
HEAT SINK: The thermoelectric (Peltier) elements do not have a sufficient heat sink, and input power heats
entire system. In such a case, there is usually some initial reduction in temperature when power to
the thermoelectric device is first turned on, but this is soon followed by a gradual heating of the
system.
OUTPUT POLARITY
REVERSED: Ensure the wire polarity is correct per schematic, and ensure proper control mode is selected.
Ensure wire attachment (polarity) to the cooling device is correct. For thermoelectric (Peltier)
modules, review the “Thermoelectric Module Mounting (TEM) Mounting Procedure”, available from
www.tetech.com, and verify physical orientation of the cold side module within the system. For TE
Technology standard cooling assemblies, verify wires are attached to proper positions on terminal
strip (see section 1.4).
SYSTEM TEMPERATURE DOES NOT RESPOND AS EXPECTED:
CONTROL TYPE
IMPROPERLY SET: Set CONTROL TYPE to PID control if you want the temperature controller to adjust the output
power based on the actual temperature and the set temperature. Set CONTROL TYPE to
COMPUTER CONTROL if you want to use an external computer to adjust the power output
manually. See Section 2.3.
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