Bimba PCS - Manual (Page 17)

www.bimba.com Technical Assistance: 800-44-BIMBA 17
Note: If the system does not move at all, go back and check all of
your connections. For Option-N models, be sure the valve cables are
connected properly. If the wires are reversed, the actuator may
move opposite of the intended direction. (i.e., zero will move the
actuator to its full scale position. If the actuator does this, reverse
the white wires from the valve cables.)
Also - If the LED’s occasionally pulse on, it may indicate a slight
leak in the system. The system will work OK with a slight leak, but
you may want to eliminate the leak so the system operates at
maximum efficiency
PTF rotary actuators less than 180 degrees of rotation
Considering all feedback potentiometers used on PTF rotary actuators have an
electrical rotation angle of 340 degrees, and that the Zero and Span adjustments
can only be adjusted down to a 50% window of total electrical span, PTF rotary
actuators less than 180 degrees of rotation will not be able to use the full scale
span of the analog command input signal, and will be treated by the Main Control
as though they are 180 degree units.
PTF’s less than 180 degrees of rotation are shipped with the feedback
potentiometer’s electrical zero set to the PTF’s rotational zero position, so when
the zero analog command input signal is applied to the PCS input, the PTF should
be very close to the zero rotational position when the zero adjustment is fully CW.
Now follow the steps below.
If the Red LED is On - (The Zero setting is currently set beyond the desired
retracted or rotational position). Adjust the Zero potentiometer CCW slowly, until
the red LED goes off. This should only be a minor adjustment. If the zero
potentiometer needed many turns of adjustment, the PTF feedback potentiometer
located on the back of the PTF may be set incorrectly, and may prohibit the Span
adjustment from being made properly. We will address this in the Span
adjustment section if necessary. (If the zero potentiometer was adjusted too far
and the actuator moved away from zero, adjust the Zero potentiometer CW just
enough to move the actuator back to the zero position. If adjusted too far, the red
LED will come back on). Both LEDs should be off when set correctly. This ends
the preliminary Zero adjustment.
If Both LEDs are Off - (The Zero setting is currently set somewhere in mid-
stroke.) Slowly adjust the Zero potentiometer CW to move the actuator rod or
towards the zero position. The red LED will flicker while being adjusted. When
the actuator hits the zero position, the red LED will continue to flicker even when
the adjustment is no longer being turned. Now adjust the Zero CCW just enough
to turn off the red LED. Both LEDs should be off when set correctly. This ends
the preliminary Zero adjustment.