Si Biased Detector
Chapter 6: Troubleshooting
Rev A December 27, 2017
Page 11
Chapter 6 Troubleshooting
Problem
Suggested Solutions
There is no signal response.
Verify that the power is switched on and all
connections are secure.
Verify the proper terminating resistor is installed if
using a Voltage measurement device.
Verify that the optical signal wavelength is within
the specified wavelength range.
Verify that the optical signal is illuminating the
detector active area.
Connect the DET to an oscilloscope without a
terminating resistor installed. Most general purpose
oscilloscopes will have a 1 M
Ω
input impedance.
For visible detectors, point the detector toward a
fluorescent light and verify that a 60 Hz (50 Hz
outside the US) signal appears on the scope. If so
the device should be operating properly and the
problem may be with the light source or alignment.
There is an AC signal present
when the unit is turned off.
The detector has an AC path to ground even with
the switch in the OFF position. It is normal to see
an output response to an AC signal with the switch
in this state. However, because the detector is
unbiased, operation in this mode is not
recommended.
The output appears AC
coupled with long rise times
and the power switch ON.
This is usually an indication that the battery level is
low and needs to be changed. See the Battery
Check and Replacement Section.
