Johnson Controls VA-9070 Series Technical Bulletin page 12

Table 1: Actuator troubleshooting chart
Problem
Corrosion inside actuator.
Servo Troubleshooting
Refer to the actuator manual before adjusting or replacing any actuator components. Before
testing or acting on any possible issues, check for any active faults.
Risk of electric shock
Turn off all power and lockout/tag out service panel before installing or modifying any electrical wiring.
Table 2: Servo troubleshooting chart
Problem
Servo NXT does not turn on
when power is applied
Actuator moves back and
forth near setpoint (hunting) Excessive noise on the signal
Servo NXT not responding to
command signal
12 VA-9070 Series Electric Rotary Actuators for Two-Position and Modulating Service Technical Bulletin
Possible Cause
Condensation forming.
Water leaking in.
WARNING
Possible Cause
Fuse is blown
Servo NXT is incorrectly wired
Servo NXT is not receiving
power
Power is not correct
Deadband is too narrow
lines
Servo NXT in local mode
Servo NXT in manual or
autocalibration mode
Servo NXT is incorrectly wired
Solution
Test heater wiring; should have
constant power.
Check all seals and possible
water entry
through conduit.
Solution
Verify and replace fuse
Verify wire connections against
the wiring diagram
Test the Input Power
connection with a multimeter
or oscilloscope
Check the provided power
against the voltage listed for
the Servo NXT and actuator
Increase the deadband setting
Use an oscilloscope to test for
the presence of EMI.
Utilize EMI reducing techniques
to mitigate the issue.
If local control is being used,
ensure the local control station
is not active or is set to remote
mode.
Check the indicators for manual
or autocalibration mode
Verify wire connections against
the wiring diagram