23
TROUBLESHOOTING
PROBLEM
POTENTIAL CAUSES
SOLUTIONS
The LDD output switched off unexpectedly
OR
I can't enable LDD output current
The output disabled due to an interlock.
Check error messages on screen or with
ERR?
query
Fix appropriate interlock or follow
instructions on Error Messages Page.
TC failure detected.
If the TC output also disabled, resolve
the source of that error. If LDD output
was remotely linked to the TC status,
but you don't want it to be linked, use
LASer:ENABle:OUTOFF
command to
unlink them.
Temperature limits have been reached.
If the temperature limits can be increased
without damage, increase the temperature
limit settings.
The TC output switched off unexpectedly
OR
I can't enable TC output current.
Check error messages on screen or with
ERR?
query, OR TC failure was detected.
The instrument detected an error. Follow
instructions on Error Messages Page.
Temperature limits have been reached.
If the temperature limits can be increased
without damage, increase the temperature
limit settings.
The instrument is on but the front panel
display is blank.
Instrument firmware is being downloaded
from USB port.
Wait patiently until the firmware has
finished updating.
The screen brightness is too low.
While the screen may appear off, the
brightness is at a low setting. Go to the
settings screen to raise the brightness
or send remote command (
BRIGHT)
to
increase brightness. If you can't see the
screen because it is too dark and don't
want to easily use the remote command,
imagine the location of the icons on the
screen. Good luck.
LD noise current is higher than expected.
Ground Loop, bad connections and solder
joints, noisy computer connections, etc.
Actual LD current does not match the
setpoint.
The setpoint exceeds the limit current
setting.
If the limit current can be increased without
damage to the laser, increase the limit
current setting.
The laser is compliance voltage limited.
If the limit voltage can be increased without
damage to the laser, increase the limit
voltage setting. See Additional Technical
Information for more details.
Temperature does not stabilize very well at
setpoint.
Poor thermal contact between components
of the thermal load.
Use thermal paste or washers between the
load/TEC and TEC/heatsink interfaces.
Make sure the temperature sensor is in
good thermal contact with the load.
Operating outside of the ideal region of the
temperature sensor.
The sensor type and bias current should be
selected to maximize sensitivity at the target
temperature. Thermistors provide the best
performance, particularly for applications
where a single setpoint temperature must
be accurately maintained. For example, at
25°C a 10 kΩ thermistor has a sensitivity
of 43 mV/°C, whereas an RTD sensor has
a sensitivity of 4 mV/°C.
Proportional control term is set too high.
Run an IntelliTune scan.
Derivative term is introducing noise.
Run an IntelliTune scan.
