Lincoln LT-7 Troubleshooting Manual page 34

B-25
TEST PROCEDURE
1. Remove the wire feed motor connector
from the LT7 control box.
2. Using the ohmmeter measure the motor
resistances per Table B.3.
Figure B.4
3. If the motor resistance test is good pro-
ceed to the Motor Applied Voltage Test.
MOTOR APPLIED VOLTAGE TEST
1. Carefully connect the 110VDC supply
(SUPPLY TURNED OFF) to pins C and D
on the motor connector.
2. Carefully connect the variable 0 to 90VDC
supply (SUPPLY TURNED OFF) to pins A
and B on the motor connector.(See Table
B.3)
TROUBLESHOOTING AND REPAIR
WIRE DRIVE MOTOR TEST ( continued )
FIGURE B.4 - Wire Drive Motor Connector Pins
#627
TEST POINTS
Lead #539 to #541
Armature
Lead #626 to #627
Field Winding
All leads
to
motor shell
LT-7 TRACTOR
#539
A
E
B
D
C
3. Apply field voltage first(pins C and D) to
the motor. Then slowly apply the arma-
ture voltage on pins A and B.(See Table
B.3)
Also see
4. The motor should run and the speed
should vary with changes to the armature
voltage.
5. If the motor does NOT run and change
speed correctly the motor or gear box
may be faulty.
6. To stop motor REMOVE ARMATURE
VOLTAGE FIRST. (Pins A and B)
TABLE B.3
RESISTANCE
4 to 5 ohms
750 to 850 ohms
500,000 ohms min.
B-25
#541
#626
DC VOLTAGE
0 to 90VDC
90 to 120VDC
NONE