Clamp Mounting On 1250, 1250R And 3024S Actuators; Mounting Bracket/U-Bolt Mounting On 657 And 667 Actuators; Changing The Input Module Diaphragm Assembly - Fisher 3660 Instruction Manual

3660 and 3661 Positioners
September 2015
1. Release all pressure from the positioner. Disconnect the supply, instrument, and output tubing. For 3661
positioners, disconnect the input wires and conduit.
2. Unscrew the two captive cover screws and remove the cover (keys 24 and 21). Loosen the retaining screw
(key 19P).
3. Pull the feedback lever assembly (key 19) out slightly to release the range spring tension, and remove the range
spring (key 30).
4. Loosen and remove the hex head screw and sealing washer (keys 72 and 71 in figure 3), and remove the positioner.
5. To mount the positioner on the actuator, refer to the Positioner Mounting section of this manual.
Clamp Mounting on 1250, 1250R, and 3024S Actuators
WARNING
To avoid personal injury caused by electrical shock, disconnect electrical power to 3661 positioners.
1. Release all pressure from the positioner. Disconnect the supply, instrument, and output tubing. For 3661
positioners, disconnect the input wires and conduit.
2. Unscrew and remove the hex nut and washer (keys 66 and 67 in figure 3), and remove the positioner.
3. To mount the positioner on the actuator, refer to the Positioner Mounting section.
Mounting Bracket/U‐Bolt Mounting on 657, and 667 Actuators
Refer to figure 24 or 25 for key number locations unless otherwise indicated.
1. Release all pressure from the positioner. Disconnect the supply, instrument, and output tubing. For 3661
positioners, disconnect the input wires and conduit.
2. Unscrew the two captive cover screws and remove the cover (keys 24 and 21). Loosen the retaining screw
(key 19P).
3. Pull the feedback lever assembly (key 19) out slightly to release the range spring tension, and remove the range
spring (key 30).
4. Loosen and remove the hex nut and washer (keys 90 and 89, figure 7), and remove the positioner.
5. To mount the positioner on the actuator, refer to the Positioner Mounting section.

Changing the Input Module Diaphragm Assembly

Refer to figure 24 or 25 for key number locations.
1. Unscrew the two captive cover screws, and remove the cover (key 21). Loosen the retaining screw (key 19P) and
pull the feedback lever assembly (key 19) out slightly to release the range spring (key 30) tension.
2. Remove the cheese head screw (key 7) from the beam and diaphragm assembly (key 28).
3. There are four cheese head screws (key 7) holding the diaphragm assembly (key 28) to the housing. Remove the
two cheese head screws (key 7) nearest the feedback lever assembly (key 19) and loosen the two remaining cheese
head screws (key 7). Slide the diaphragm assembly (key 28) out from between the lever assembly (key 17) and the
housing.
4. Install the new diaphragm assembly (key 28), and secure with the four cheese head screws (key 7).
5. Depress the feedback lever assembly (key 19) inward until it stops on the housing, and tighten with the retaining
screw (key 19P).
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Instruction Manual
D101402X012