Control Assembly Service
Potentiometer Removal
Remove the potentiometer as follows:
ELECTROCUTION HAZARD
Installing and servicing this equipment requires access to parts which could cause an electric shock or other serious injury. Have only qualified electricians access the control assembly.
1.Shut off system power at the main circuit breaker.
2.At the control assembly, move the MAIN power switch to the OFF position.
3.Unlock and open the hinged cover of the control assembly.
4.Pull lead wires to remove from potentiometer.
5.Loosen setscrew (not shown) in the vernier dial knob and remove dial assembly from the potentiom- eter shaft.
6.Remove the hex nut and lockwasher from potenti- ometer shaft, and remove the potentiometer.
Vernier dial
Cover
Potentiometer
3 1 2
Potentiometer Replacement
Replace the potentiometer as follows:
1.Insert the potentiometer through its hole from the back of the enclosure cover and rotate it so that ter- minals 1 and 3 are oriented at approximately 4:30 when viewed from the back. Refer to FIG. 16. Assemble the lockwasher and nut onto the shaft and secure the potentiometer to the cover.
2.At the front of the cover, turn the potentiometer shaft
3.
4.Verify that the potentiometer is turned fully counter- clockwise when the vernier dial indicates 0.00. Loosen the setscrew and reposition the shaft and dial if necessary, then retighten the setscrew.
5.Connect wire leads to potentiometer.
6.Close and lock the cover on the control assembly.
7.Apply system power at the main circuit breaker.
8.Move the MAIN power switch to the ON position, applying power to the control assembly.
9.In the MANUAL control mode, verify that the potenti- ometer operates correctly.
10.Return the orbital dispenser and control assembly to normal operating condition.
Terminals 1 and 3
Nut
2172
2132
Locating2181 Tab
8040A
FIG. 15
Terminal 2
2181
2132
2172
8034B
FIG. 16
28 | 310554V |
