LDTC-LAB datasheet(24/31 Pages) WAVELENGTH

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PROBLEM

POTENTIAL CAUSES

SOLUTIONS

Using a resistive heater, temperature

is slow to stabilize and is not within the

specifications.

Setpoint temperature is set too close to the

ambient temperature.

Set the temperature at least 10°C above ambient

when using a resistive heater. A resistive heater

is unable to precisely maintain temperatures

near ambient because once the temperature

overshoots the setpoint, the controller turns off

and relies on ambient temperature to cool the

load. If setting the temperature 10°C or more

above ambient is not possible, then choose

a thermoelectric, which can alternately heat

and cool the load to maintain a more precise

setpoint temperature.

Airflow across load is inadequate.

Use a fan to blow air across the load to

increase natural convection.

Temperature does not reach the setpoint.

Insufficient current driven to the TEC or

heater.

Increase the current limit, but DO NOT

exceed the specifications of the TEC/RH.

The controller does not have sufficient

compliance voltage to drive the TEC or

heater

Check the thermoelectric voltage and

determine if it is too close to the 15 V

maximum. If it is, choose a lower voltage

thermoelectric.

Temperature differential may be too great.

Check TEC

TMAX. What is heatsink

temperature minus T?

Temperature

increases

beyond

the

setpoint and will not come down.

The TEC and heatsink are not adequately

sized for the thermal load.

The system is in "thermal runaway."

The heat being generated by the load

may be too great for the TEC to pump to

the heatsink; a larger TEC or heatsink, or

airflow may be needed. Consult Technical

Note TN-TC01: Optimizing Thermoelectric

Temperature Control Systems.

Actual temperature does not approach

setpoint after output current is enabled.

Thermoelectric wiring is reversed.

Reverse the leads to the thermoelectric.

The thermoelectric is generating too much

heat and has inadequate cooling.

Install a larger heatsink or a fan to cool the

heatsink.

I hear a beep and know there is an error,

but nothing is displayed on the instrument

screen.

A remote command REMERR 1 needs to

be sent to the instrument to display errors.

Connect the LDTC LAB to a remote

computer and write the REMERR 1

command. See the Remote Command set

document for more information.

My instrument doesn't show up in the list.

(REMOTE ONLY)

Instrument may not be turned on.

Power up the instrument and click

Refresh

on the

Choose Instrument window.

Your instrument may not be plugged into

the computer.

Check that a USB cable is tightly connected

to the instrument and to the computer.

IntelliTune fails because of a sensor error.

Sensor voltage may be too high or too low,

which triggers a bias current change.

Choose a setpoint such that the sensor

voltage will be between 0.075 V and 10 V.

The sensor signal will be in range during

all of the sweeps and not trigger a bias

current change.

Select a fixed bias current. Review the

TCS Series Thermistors Datasheet

for

temperature-resistance-voltage

relationships.

IntelliTune fails because of a "load short"

error.

The load compliance voltage is too low

Put a resistor in series with the

thermoelectric to increase the load

compliance voltage.

Decrease Cable Resistance.

Can't clear an on-screen error message.

The cause of the error may not have been

fixed.

Clear the error on screen. If the cause

of the error is not corrected, the error

message is displayed again.

IntelliTune gives me different answers

when I run a scan.

System has not reached thermal

equilibrium.

The characteristics of the load will change from

initial start with all parts at room temperature

to when parts are at desired operating

temperatures. Run IntelliTune once all

elements of the system have reached operating

temperature.

LDTC-LAB Datenblatt(PDF) 24 Page - Wavelength Electronics, Inc.

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