63
80-1403-01, Rev. 3
TROUBLESHOOTING USING
LOCAL LEDs
All DCM-3’s include built-in self-test routines
that run continuously. These routines can simplify
the troubleshooting process.
Detail 1: The PWR (power) LED.
Is the PWR LED illuminated? The PWR LED
should be illuminated whenever power is connected
to the actuator. A cleared fuse on the DCM-3 does
not prevent the PWR from lighting. The PWR
LED being illuminated does not mean power is
within specification. The LED will illuminate with
approximately 70V ac applied to the actuator.
Is the PWR LED pulsing? The PWR LED
should be changing brightness approximately each
second (60 times per minute). This brightness
change indicates that the self-test routines are
running and have not found any errors in the DCM-3
microcomputer operation. This does not mean all
the process variables are within acceptable limits
or that the DCM-3 is operating exactly correctly,
but does mean that the onboard microcomputer is
running properly.
Detail 2: The FWD and REV LEDs
If the DCM-3 is trying to run the motor, either
the FWD or the REV LED’s should be illuminated.
If the motor is running without one of the LED’s
illuminated, then either the DCM-3 is being
bypassed (perhaps by the Handswitch), or the
power output stage of the DCM-3 is “stuck” on.
The FWD and REV LED’s indicate the signal
level comparison between the Demand and the
output shaft position (as measured by the CPS-5).
FWD illuminated indicates the Demand is higher.
REV illuminated indicates Demand is lower. Both
OFF indicates either the signals are balanced, or
that the DCM-3 has detected some status that
prevents the motor from being run.
Detail 3: The STAT LED
The STAT (status) LED indicates the DCM-3 is
aware of a problem. The severity of the problem is
not immediately apparent through the STAT LED.
Problems can range from relatively minor to major.
The following table lists the alarms and what
the alarm means with regard to stopping the motor.
Y – alarm stops motor
N – alarm does not stop motor
C – circumstances and configuration matter
R – result of switch stopping motor
Alarm
Stop
Motor?
Local Configuration
Panel LED
Demand LOS
C
DEMAND
DemandMeasFail
C
DEMAND
DemandTooHigh
C
DEMAND
DemUnderHART/FF Ctl
C
DEMAND
DemUnderPAT Ctl
C
DEMAND
Torq/Thrust High
Not active in Group 14
Torq/Thrust Stop
Not active in Group 14
Torq/ThrustMeasFail
Not active in Group 14
Stall
Y
STALL
Stop/Limit
R
STOP/LIMIT
FeedbackLOS
N
FEEDBACK
Temperature
N
TEMP
PositionLOS
Y
POSITION
PositionA/D Error
Y
POSITION
RTC Fail
N
—
TemperatureMeasFail
N
TEMP
MemoryFail
N
—
