MTS DCPD Measurement System - Manual (Page 43)

Solution Problem
3) Verify that the gains in the controller for the appropriate signal are
not zero.
4) Verify the continuity of the cable is good, by testing the continuity of
pins 4 and 7 on the RJ50.
Verify that the green light is lit on the front of the DCPD unit. (It should
always be on when using reversing). Voltage does not reverse.
If the green light is not lit, see the “Always have red light on front of unit”
problem.
If Green light is lit:
First verify a voltage change when the unit turns on and off. Verify the
Forward/Reverse digital input is closed. Look in the Digital Outputs of
the Station Manager and verify the digital output is closed (green in
Station Manager). If it is green, and the DCPD unit is green, read the
voltage on a Station Manager meter or on the Station Manager scope.
Now switch the ON/OFF digital output to OFF. The red light should be
lit on the unit. Now verify that the voltage read by the meter or scope
is different than the previous reading. In the scope, you should see a
square wave corresponding to switching the digital output ON and OFF.
If the voltage never changes, see the “Voltage never changes but the
green light is on” problem.
Next, leave the ON/OFF digital output ON, and switch the Forward/
Reverse Digital Output ON and OFF. You should see a change in the
values on the Station Manager scope or meter. The green light on the
DCPD unit should always be lit.
If the Green light goes on and off when the Forward/Reverse digital
signal is switched, then there is a problem in you configuration of the
digital signals. (The signals might be swapped in Station Builder.)
If the voltage never changes, see the “Voltage never changes but the
green light is on” problem.
Depending on the amplification, variability in voltage reading is normal.
The voltage can be higher when specimen is being cycled mechanically, Voltage changes from reading to
reading.
or if the specimen is changing temperature. The low pass filter switch
set to 50 Hz will help minimize this noise, but best practices usually
require oversampling and averaging of the DCPD voltages to get good
results.
Voltage shift while heating specimens: Due to the electrothermal
behavior of specimens, there can be a shift in displayed mean voltage
values as specimen temperature changes. This is normal behavior and
is to be expected. Once the specimen temperature is constant, voltage
drift should not occur. Similar behavior might initially be observed at
room temperature, if specimen current results in specimen temperature
change. Once specimens reach a steady state, voltage drift should not
occur. If the selected current results in undesired specimen heating,
use a smaller current.
DCPD Measurement System | 43
Troubleshooting