Lincoln Electric LF-72/74 DD-2, To verify the wire feed speed, Such as output terminals or inter

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DD-2		MAINTENANCE						DD-2
MAINTENANCE			Calibration of the LF-74 may be required when the p.c.
Safety Precautions			board, potentiometer or motor is replaced or serviced.
			Calibration matches the scale on the name plate to the
			actual wire feed speed.
	WARNING
			To verify the wire feed speed,
	ELECTRIC SHOCK can kill.
			1. Assemble a .045 (1.2 mm) drive roll kit to the feed-
	• Do not touch electrically live parts		er.
			2. Load .045 (1.2 mm) steel wire into the feeder.
	such as output terminals or inter-
			3. Trim the wire to the end of the contact tip of the gun.
	nal wiring.
			4. Adjust the WFS knob per the Table D.1.
• When inching with gun trigger, electrode and						TABLE D.1
drive mechanism are “hot” to work and ground
					MODEL		WFS knob setting
and could remain energized		several seconds
				K2426-1, K2426-1			400
after the gun trigger is released.
					K2426-3		200
• Turn OFF input power at welding power source
before installation or changing drive roll and/or			5. Activate and hold the COLD FEED switch for 10
guide tubes.
			seconds.
• Welding power source must be connected to sys-
			6. Measure the length of wire extending from the con-
tem ground per the National Electrical Code or
			tact tip. The wire length shown in Table D.2.
any applicable local codes.
						TABLE D.2
• Only qualified personnel should perform mainte-
nance work.			MODEL				WIRE LENGTH
			K2426-1, K2426-1			50 inches ± 5 inches (1270 mm ± 127mm)
------------------------------------------------------------------------
			K2426-3			25 inches ± 2.5 inches (635 mm ± 64 mm)
Observe all additional Safety Guidelines detailed
throughout this manual.			To calibrate the wire feed speed,
ROUTINE MAINTENANCE			Tools required:
• Clean and tighten all weld terminals.			• 5/16" nut driver
• Inspect all weld cables, control cables, gun cables			• 3/4" open end wrench
and shielding gas hoses. Repair or replace as nec-			• WFS meter or RPM meter
essary.			• Shorting plug. The shorting plug shorts pins 1 and 5
			of connector J2 on the p.c. board. J2 is a 6 pin

PERIODIC MAINTENANCE molex.

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•Clean drive roll grooves.

•Blow out or vacuum the inside of the feeder.

CALIBRATION SPECIFICATION

WARNING

ELECTRIC SHOCK can kill.

•Do not touch electrically live parts.

•When inching with the gun trigger, electrode, wire drive motor and drive mechanism are "hot" to work and ground and could remain energized several seconds after the gun trigger is released.

•Welding power source must be connected to system ground per the National Electrical Code or any applicable local codes.

•Only qualified personnel should perform mainte- nance work.

------------------------------------------------------------------------

1.Turn off power to the LF-74 and welding power source.

2.Disconnect the electrode lead from the feed plate and from the welding power source.

3.Remove the wraparound from the LF-74, See Figure D.1.

4.Turn on power to the LF-74 and welding power source.

5.Adjust the WFS knob per the Table D.1.

6.Insert the shorting plug into the control p.c. board J2. (shorts pins 1 and 5.) See Figure D.2.

7.Wait a minimum of 1 second.

8.Remove the shorting plug.

9.Connect J2 of the harness to p.c. board.

10.Turn off power to the LF-74 and welding power source.

11.Assemble the wraparound.

12.Connect the electrode lead.

LF-72/74