Retest After Repair; Check Wire Feed Speed - Lincoln LN-742 Service Manual

F-34
TROUBLESHOOTING AND REPAIR

RETEST AFTER REPAIR

If a failed test indicates that any mechanical
part which could affect the machine's
electrical characteristics must be replaced,
or if any electrical components are repaired
or replaced, the machine must be retested
and meet the following standards.
1. Apply input power to the wire feeder (42
VAC).
2. Press the Purge key. The gas solenoid
should activate, then deactivate when
the key is released.
3. Press the Inch key. Check that the
direction of rotation of the drive roll
shaft is correct to feed wire out of the
front of the machine. Check that the
drive roll shaft stops abruptly when the
key is released.
4. Press the Increase Arrow key. The
number displayed should increase.
5. Press the Decrease Arrow key. The
number displayed should decrease.
6. Press the Function Select key. The
7. Press the Mode Select key. The LEDs
8. Press the Timer Select key. The LEDs
NOTE: The Spot timer LED will not light
unless the trigger is in the Spot mode.

CHECK WIRE FEED SPEED

LN-742 2 roll . . . . 50 through 770 in./min.
LN-742H 2 roll . . . 80 through 1200 in./min.
LN-742 4 roll . . . . 50 through 770 in./min.
LN-742H 4 roll . . . 80 through 1200 in./min.
LN-742 & LN-742H
LEDs should toggle through the various
selections.
should toggle through the various
selections.
should toggle through the various
selections.
F-34