Routine Maintenance; Periodic Maintenance; Calibration Specification - Lincoln Electric FLEX FEED 74 HT Operator's Manual

FLEX FEED™ 74 HT
SAFETY PRECAUTIONS
WARNING
ELECTRIC SHOCK can kill.
• Turn the input power OFF at the welding
power source before installation or changing
drive rolls and/or guides.
• Do not touch electrically live parts.
• When inching with the gun trigger, electrode and drive
mechanism are "hot" to work and ground and could
remain energized several seconds after the gun trigger is
released.
• Do not operate with covers, panels or guards removed or
open.
• Only qualified personnel should perform maintenance
work.
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ROUTINE MAINTENANCE

Check weld cables, control cables and gas hoses for
cuts.
Clean and tighten all weld terminals.

PERIODIC MAINTENANCE

Clean the drive rolls and inner wire guide and replace if
worn.
Blow out or vacuum the inside of the feeder.
Inspect the motor brushes every 6 months. Replace if
shorter than 0.5" (12.7mm).

CALIBRATION SPECIFICATION

Wire Feed Speed Validation
Calibration matches the scale on the name plate to the
actual wire feed speed. As shipped from the factory, the
wire feeder is calibration for 0.45 (1.2mm) wire.
Calibration of the Flex Feed™ 74 HT may be required
when the p.c. board, the wire feed speed potentiometer
or the motor is replaced or serviced.
To calibrate the Flex Feed™ 74 HT:
1. Turn power OFF at the welding power source.
2. Remove the (4) screws holding the roof of the wire
feeder to gain access to the pc board.
3. Turn power ON and trigger the Flex Feed 74 HT.
4. Set the WFS knob to 50 in/min and measure the drive
roll rpm. If the drive roll rpm measures 8.9 to 9.2 rpm,
proceed to step 7.
5. Unplug the connector in J2. Insert a shorting plug that
shorts pin 1 and 5. Adjust the WFS knob as required
until drive roll rpm measures:
• 5.93 to 6.13 rpm for 20 tooth pinion gear.
• 8.90 to 9.20 rpm for 30 tooth pinion gear.
6. Remove the shorting plug from J2.
7. Set the WFS knob to 300 in/min. Measure the drive roll
rpm. If the drive roll rpm measures 53.97 to 55.17, pro-
ceed to step 10.
8. Unplug the connector in J2. Insert a shorting plug that
shorts pin 1 and 5. Adjust the WFS knob as required
until drive roll rpm measures:
• 35.9 to 36.7 rpm for 20 tooth pinion gear.
• 53.97 to 55.17 rpm for 30 tooth pinion gear.
9. Remove the shorting plug from J2.
10. Set the WFS knob to 500 in/min for the 20 tooth pin-
ion gear or 700 in/min for the 30 tooth pinion gear.
Measure the drive roll rpm. If the drive roll rpm mea-
sures 89.9 to 91.9, proceed to step 13.
11. Unplug the connector in J2. Insert a shorting plug
that shorts pin 1 and 5. Adjust the WFS knob as
required until drive roll rpm measures:
• 83.87 to 85.87 rpm for 20 tooth pinion gear.
• 126.32 to 128.32 rpm for 30 tooth pinion gear.
12. Remove the shorting plug from J2.
13. Turn power OFF and reassemble.
D-1
MAINTENANCE