C A L I B R A T I O N A N D T R O U B L E S H O O T I N G
Troubleshooting
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LDC-3700 Series
129
C H A P T E R
5
Troubleshooting
This section is a guide to troubleshooting the LDC−3700B Series Controllers. Some of the more
common symptoms are listed here, and the appropriate troubleshooting actions are given. We
recommend that the user start at the beginning of this guide. Read the symptom descriptions, and
follow the steps for the corrective actions which apply. If you encounter problems which are beyond
the scope of this guide, contact your ILX Lightwave customer service representative.
Table 5.3
Symptoms and Actions
Symptom
Corrective Actions
General
LDC−3700B Series unit will not power up
Check AC Power line voltage and power cord connection.
Power on, but display is frozen, switches do not
operate
This may occur if the instrument loses power (AC line)
briefly. Turn the power switch off and on again to restart.
Laser Contoller
Power on, but no current output
Check Interlock pins on LASER input connector on
instrument rear panel. These pins must be shorted either
directly or through a switch.
If OPEN CIRCUIT indicator is lit check the load
connections and then try again.
Check the OUTPUT ON switch, the corresponding LED
should be lit.
Output current at limit, cannot be lowered
If POWER mode is used, check the monitor diode
(feedback) connections. Try reversing the polarity of the
monitor photodiode. Check also the photodiode bias
adjustment on the rear panel.
If in I or I
HBW
mode, check the current set point and I LIMIT
setting. Setting the output below the limit may require
several turns of the adjust knob if the set point is much
greater than the desired limit setting.
Output goes off intermittently
Check the interlock circuit. An intermittent interlock will
turn the output off.
Check that the AC power cord connection is secure.
Power−line drop−outs may reset the unit and when power is
restored, the output will be off.
Unable to adjust output
Check the (ADJUST) LASER indicator, the indicator must
be lit for any LASER adjustments to be made.
Check the I LIMIT parameter for the output range in use,
see that it is set above 0 mA.
Power Mode operation has high output current,
but little or no power is measured
Check back panel PD BIAS. If set too low, may act as an
open feedback loop. If in doubt, set the PD BIAS to mid
range (2.5 V).
Output exceeds Power Limit
The "Power Limit" is not a hardware limit. It only serves as
a warning that the power measurement has exceeded the
limit set point.
Open Circuit Error occurs during calibration
Check load connections. Check that measuring meter
does not auto−range (use non−auto−ranging modes).
Calibration is aborted unintentionally
Calibration modes will be aborted if an open circuit is
detected.
VOLTAGE LIMIT indicator blinks
This indicates a voltage limit error. Check laser
connections. A high impedance may cause this condition.
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