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Section 7
DIAGNOSTIC TESTS
4. If no movement is seen in Step 3 remove the con-
trol panel cover. Verify the six pin connector (J2)
on the Printed Circuit Board is seated properly,
remove the connector and then replace it and test
again. Verify the dip switches are correctly set.
NOTE: The dip switches on the Printed Circuit
Board are factory set in the “OFF” or DOWN posi-
tion. Refer to Figure 5.2 on Page 22.
5. If problem continues remove six pin connector
(J2) from Printed Circuit Board. Set Volt meter to
measure ohms. Carefully measure from the end
of the six pin harness as follows:
RED
EMPTY
YELLOW
BROWN
ORANGE
BLACK
Figure 7-2. Six Pin J2 Connector Wire Colors
NOTE: Press down with the meter leads on the
connectors exposed terminals, do not probe into
the connector.
a. Connect one meter lead to Red, connect the
remaining test lead to Orange, approximately 10
ohms should be measured.
b. Connect one meter lead to Red, connect the
remaining test lead to Yellow, approximately 10
ohms should be measured.
c. Connect one meter lead to Red, connect the
remaining test lead to Brown, approximately 10
ohms should be measured.
d. Connect one meter lead to Red, connect the
remaining test lead to Black, approximately 10
ohms should be measured.
e. Connect one meter lead to Red, connect the
remaining test to the stepper motor case. No
resistance should be measured (“Infinity” or
Open).
RESULTS:
1. If the stepper motor fails any part of Step 5
replace the stepper motor.
2. If the stepper motor passes all steps replace the
Printed Circuit Board.
TEST 4 – FIXED EXCITATION TEST/ROTOR
AMP DRAW
DISCUSSION:
The fixed excitation test consists of applying bat-
tery voltage (12 VDC) to the Rotor windings. This
allows that portion of the excitation circuit between
the Voltage Regulator and the Rotor (including the
Rotor itself) to be checked as a possible cause of the
problem. When battery voltage is applied to the Rotor,
the resulting magnetic field around the Rotor should
induce a Stator power winding voltage equal to about
one-half the unit’s rated output voltage.
6
0
4
13
13
2
4
22S
11S
15
JUMPER WIRE
WIRES 4 REMOVED FROM
VOLTAGE REGULATOR
VOLTAGE
REGULATOR
FUSE HOLDER (F1)
RED TEST LEAD
BLACK TEST LEAD
Figure 7-3. – Fixed Excitation Test, Step A
PROCEDURE:
1. Disconnect Wire 4 from the Voltage Regulator
(VR). (Third terminal from the right side of VR).
2. Connect a jumper wire to Wire 4 and to the 12 volt
fused battery positive supply Wire 15, located at
the fuse (F1) holder (see Figure 7-3).
NOTE: During this test, Wire 15 must remain con-
nected to the fuse (F1) holder.
3. Set the VOM to measure AC voltage.
Page 37