QAL Medical 480, Service And Technical Manual

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9
4 KNEEPOT (Potentiometer)
(480/480E/480E PRO)
4.1 Kneepot Cover
note:
Plastic rivets may be re-used if not damaged during removal.
Removal:
1. With a pair of diagonal cutters, carefully remove the rivets to free the kneepot cover.
2. Remove the kneepot cover.
Important:
Remove center of kneepot rivet from casting by moving outer thigh tube so they fall out.
Installation:
1. Install the kneepot cover over the casting, aligning the cable with the small divot in the cover and the holes
in the plastic with the holes in the casting.
2. Install the rivets in their appropriate holes and insert the plastic rivet centers.
3. With a small hammer gently tap the centers of the plastic kneepot rivets flush with the rivet casting.
4.2 Kneepot cable
Removal:
1. Remove the bottom cover (refer to section 2.1).
2. Remove kneepot cover (refer to section 4.1).
3. Remove kneepot cable plug from the socket on the main PC board.
4. With diagonal cutters, remove all ty-raps from the kneepot cable.
5. Remove strain relief from top cover by removing the nut on the underside strain relief side of the top cover.
6. Pull cable through cover.
7. De-solder the cable from the terminals on the kneepot.
Installation:
1. Wrap wires one and one-quarter turns around kneepot terminals and solder as follows:
480: pin #1 - white, pin #2 - red, pin #3 - black
480E: pin #1 - black, pin #2 - red, pin #3 - white
2. Install kneepot cover (refer to section 4.1 ).
3. Carefully put kneepot cable through top cover. Feed the free end of the cable through the hole in the top
cover until the cable strain relief is reached (only tighten the strain relief nut 1/4 turn past finger tight).
4. Put rubber washer on kneepot cable.
5. Install bottom strain relief nut on kneepot cable.
6. Tighten strain relief bottom nut 1/4 turn past finger tight.
7. Install the kneepot cable plug onto the main PC board connector pins 1,2,3.
8. Gather excess cable and secure to the front of the base frame with a ty-rap.
9. Install bottom cover (refer to section 2.1).
4.3 Knee Potentiometer (POT) Replacement
Removal:
1. Remove Knee Potentiometer cover (4.1).
2. De-solder wires from Potentiometer.
3. Insert the tip of a small screwdriver into the notch in the casting beside the Potentiometer and pry
Potentiometer away from casting.
4. Retain Potentiometer Drive Coupling.