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TROUBLESHOOTING
Error
Actuator at one end of
stroke and does not
respond to input change
(continued)
Excessive air consumption
(exhaust loud)
Slow response
Full range cannot be
obtained with mechanical
zero and span adjustment
Unable to match setpoint
and feedback voltages in
troubleshooting calibration
adjustments in
Section 4
Servo output pressure not
20 to 103 kPa (3 to 15 psig)
after troubleshooting cali-
bration adjustments
INTRODUCTION
6 - 2
Table 6-1. Positioner Errors
Probable Cause
Pneumatic signal leak.
Mechanical calibration
shift (zero or span shift).
Servo not functioning.
Leakage at the joint of
the manifold assembly
(if equipped).
Pilot valve leaking.
Tubing disconnected.
Pilot valve blocked.
Signal diaphragm leak-
ing.
Servo out of calibration
or not functioning.
Motor control circuit
board is faulty.
Servo is defective.
(continued)
Corrective Action
Check signal at I port. If pressure is between
20 to 103 kPa (3 to 15 psig) and does respond
to input signal change then problem exists
elsewhere.
If pressure not between 20 to 103 kPa (3 to 15
psig) or does not respond to input change,
then check for leaks inside positioner and
check servo calibration (refer to
SHOOTING CALIBRATION ADJUSTMENTS
in Section 4).
Recalibrate the mechanical zero and span.
Refer to
GENERAL CALIBRATION
Section 4.
Check servo calibration. Refer to
SHOOTING CALIBRATION ADJUSTMENTS
in Section 4.
Remove manifold and check the O-rings.
Refer to
MANIFOLD
in Section 8.
Remove pilot valve body and check O-rings.
Refer to
PILOT VALVE BODY
Check connection at pressure regulator and
servo.
Remove and clean. Refer to
BODY
in Section 8.
Replace diaphragm. Refer to
ASSEMBLY
in Section 8.
Calibrate servo. Refer to
TROUBLESHOOT-
ING CALIBRATION ADJUSTMENTS
Section 4.
Replace the motor control circuit board, refer
to
SERVO ASSEMBLY AND ELECTRONICS
CIRCUIT BOARD
in Section 8.
Replace servo. Refer to
SERVO ASSEMBLY
AND ELECTRONICS CIRCUIT BOARD
Section 8.
TROUBLE-
in
TROUBLE-
in Section 8.
PILOT VALVE
DIAPHRAGM
in
in
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Table of Contents
Troubleshooting
