Lincoln Electric IM812-A - Manual (Page 20)

D-2 MAINTENANCE D-2
ADJUSTING SPEED
SENSOR MODULE
The LN-35 Speed Sensor Module is a three lead Hall
Effect switch device encased in an externally threaded
housing which is screwed into a mounting plate on the
motor side of the wire drive gearbox.
Proper positioning of this module is critical to proper
operation of the LN-35 wire feed speed control. If the
device is not screwed in far enough, the LN-35 motor
speed could be unstable or run at full speed with no
control. If screwed in too far, it will rub a moving part
inside the gearbox.
The module is properly mounted to the gearbox
as shipped from the factory. If the device is ever
removed or replaced, proper mounting technique is as
follows:
1. Be sure all power to the LN-35 is shut off at the
power source.
2. Check that the module mounting plate is screwed
securely to the side of the gearbox.
3. Gently screw the module into the mounting plate
until it just touches and stops against the rotating
part inside the gearbox.
4. Back the module out 1/2 turn, then snug the
module lock nut without rotating the module
position. Do not overtighten lock nut.
CALIBRATION OF LN-35 WIRE
SPEED DIAL
Calibration of the LN-35 Wire Speed dial is achieved
by proper mounting of the dial knob to the speed
potentiometer shaft. Whenever the knob is removed,
the dial is recalibrated as follows:
NOTE: Knob set screw does not seat on shaft flat.
1. Be sure the Wire Speed potentiometer mounting
nut is securely tightened, then rotate the
potentiometer shaft so its flat faces about to the
100 mark on the calibrated dial.
2. Set WIRE FEED MODE switch to CV position.
3. Press gun trigger to feed wire and measure
the wire feed speed (IN/MIN) using a Portable
Digital Wire Feed Speed Meter (Lincoln K283).
Take at least two readings to assure repeat-
able accuracy.
Feed Speed Meter (Lincoln K283). Take at least
two readings to assure repeatable accuracy.
Electrode will be electrically “ hot ” . Do not allow
fed wire to contact any metal common with
welding work.
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An alternate means to measure wire feed speed
is as follows:
a. Cut wire off at the end of the gun tip.
b. Press trigger to feed wire for exactly 30 seconds.
c. Cut fed wire off at the end of the gun tip and
accurately measure its length.
d. Multiply the measured length by 2 to obtain the
wire speed (IN/MIN).
e. Repeat above steps to assure repeatable accu-
racy.
4. Carefully slip speed knob onto potentiometer
shaft so it points precisely to the wire speed
measured in step 3, then secure the knob set
screw without disturbing the position. Recheck by
repeating step 3.
LN-35
WARNING