Disassembling And Assembling Relay Components - Fisher 3660 Instruction Manual

Instruction Manual
D101402X012
6. With the input pressure set at either 1.4 or 2.4 bar (20 or 35 psig), check for leaks between the diaphragm assembly
and the housing.
7. Refer to the Calibration section for the calibration procedure.

Disassembling and Assembling Relay Components

Before disassembling the relay components, remove the positioner from the actuator. Refer to the Removing the
Positioner from the Actuator section. Refer to figure 24 or 25 for key number locations.
1. To disassemble the relay valve assembly (key 2) or restrictor assembly (key 4), unscrew these parts from the back of
the positioner and replace with new parts.
The relay valve assembly (key 2) and the restrictor assembly (key 4) are marked with the letters V and P, respectively
on the removal screws. For correct location purposes, these same letters appear on the back of the positioner case.
2. Unscrew the two captive cover screws, and remove the cover. Loosen the retaining screw (key 19P) and pull the
feedback lever assembly (key 19) out slightly to release the range spring (key 30) tension. Remove the range spring
(key 30).
3. Remove the cheese head screw (key 7) from the lever assembly (key 17) and the diaphragm assembly (key 28).
4. Remove the two cheese head screws (key 7) that hold the lever assembly (key 17) to the housing and lift off the
lever.
5. Remove the four cheese head screws (key 11) and four washers (key 98). Lift off the flapper (key 9), flapper spring
stop (key 99), flapper spring (key 10) and cover plate assembly (key 8). Lift out the output diaphragm assembly
(key 29) and spring (key 3).
6. Reassemble the relay parts in the following order, spring (key 3), output diaphragm assembly (key 29), cover plate
assembly (key 8), flapper spring (key 10), and flapper spring stop (key 99). Install the four washers (key 98) and four
cheese head screws (key 11), and then tighten the screws. When tightening the two screws that secure the flapper
spring (key 10), position the spring so the spring tab is aligned over the center of the nozzle and the flapper is
parallel as shown in figure 22.
Figure 22. Flapper and Lever Alignment
INPUT
DIAPHRAGM
ASSEMBLY
LEVER TO INPUT
MODULE MOUNTING
SCREW
A4042‐1
7. Reassemble the lever assembly (key 17) with the two cheese head screws (key 7). Do not tighten the screws until
the adjusting screw (key 18) to flapper (key 9) and tapped hole in the diaphragm assembly (key 28) are aligned
(refer to figure 22). Then, tighten the lever assembly and install the screw in the diaphragm assembly.
SPRING
TAB
LEVER MOUNTING
SCREWS
3660 and 3661 Positioners
FLAPPER ALIGNED
PARALLEL
ADJUSTING
SCREW / FLAPPER
ALIGNMENT
SPRING TAB
ALIGNED OVER
CENTER OF
NOZZLE
September 2015
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