Lincoln Electric 50448 Service Manual page 64

WIRE DRIVE MOTOR TACHOMETER TEST (continued)
TEST PROCEDURE
Use always electrically insulate gloves during this test procedure
1. Remove input power from the wire feed unit.
9. Perform the wire feeder case removal procedure taking care of do not disconnect the Motor Control board
harnesses.
2. Located the wire drive motor. See Figure 1.
3. Apply the correct input power to the wire feeder connecting it through control cable to the power source.
4. Check at connector X9 (for LF52D) or X10 (for LF56D) between pin 3 (wire 285) and pin 5 (wire 287), see wirng
diagrams, for approximately 5 VDC. If the 5VDC are missing check for loose or faulty connection between
connector X9 or X10 and Motor Control board. If connection are good, may be the Motor Control board is faulty.
5. With the trigger pressed and the motor running check at connector X9 (for LF52D) or X10 (for LF56D) the
tachimeter feedback voltage between pin 4 (wire 286) and pin 5 (wire287). Normal feedback value should be about
2,5VDC. If the correct 5 VDC supply are present but the voltage feedback is missing, the tachimeter is faulty.
6. With the motor not running the tachimeter voltage feedback may be 0VDC or 5VDC depending the position where
the tachimeter magnet, mounted on the motor axle, has stopped.
Wire drive motor
and tachometer
Figure 1 – Wire drive motor and tachometer location
LF 52D
LF 56D