Servo Assembly And Electronics Circuit Board - ABB AV3 Instruction Manual

REPAIR/REPLACEMENT PROCEDURES
5. Replace O-rings. Clean O-ring grooves and apply Dow Corning
No. 4 or equivalent lubricant to the O-rings.
6. Set (replacement or clean) valve body in place.
7. Secure valve body by replacing and tightening pilot valve screws
to 2.6, ±0.2 Nm (23, ±2 in-lbs).
8. Make certain valve stem is clean (refer to Section 7). Install valve
stem.
9. Install valve clip.
10. Transfer the positioner back to automatic operation (refer to
Section 5).
11. Perform the procedure outlined in PILOT VALVE STROKE
ADJUSTMENT.

SERVO ASSEMBLY AND ELECTRONICS CIRCUIT BOARD

This procedure details the steps necessary to remove the servo
assembly (part number 6639300_ ) and the electronics circuit board
(AV3, part number 6639917_1 or AV4, part number 6639473_1) from
the EMI/electronics housing. Use this procedure if you are replacing
either or both items. (Item numbers reference Figures 9-1 through 9-6
depending on positioner type.)
Tools Required Flat-tip screwdriver
Philips screwdriver
Pliers
1. Transfer the positioner from automatic to manual operation (refer
to Section 5).
2. Remove positioner cover by removing two cover screws.
3. Remove the two (AV3) or three (AV4) wires that connect the
servo and EMI/electronics housing assembly to terminal block (item
59).
4. Remove the indicator (item 19) and cam (item 13) by removing
the screw securing the indicator. Remove the cam nut and washer
(Figures 9-1 through 9-6). Set the cam and related items aside.
5. Loosen the three screws (two Phillips head and one socket head)
that secure the servo assembly to the positioner housing (Fig. 8-4)
and partially remove the servo. If replacing only the motor control
board, go to Step 10.
SERVO ASSEMBLY AND ELECTRONICS CIRCUIT BOARD
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