Lincoln Electric 7FH manual Problems

PROBLEMS

PROBLEM	POSSIBLE CAUSE	WHAT TO DO
3. Poor arc striking with sticking or	a. Improper procedures or	a. See “Gas Metal Arc Welding
“blast-offs”, weld porosity,	techniques.	Guide” (GS-100).
narrow and ropy looking bead,
or electrode stubbing into plate	b. Improper gas shielding.	b. Clean gas nozzle. Make certain
while welding.		that gas diffuser is not empty or
		turned off. Make certain gas flow
		rate is proper.
		Remove gun liner and check
		rubber seal for any sign of
		deterioration or damage. Be sure
		set screw in brass connector is in
		place and tightened against the
		liner bushing.
4. Tip seizes in diffuser.	a. Tip overheating due to prolonged	a. Do not exceed current and duty
	or excessive high current and/or	cycle rating of gun.
	duty cycle welding.
		A light application of high
		temperature antiseize lubricant
		(such as Lincoln E2607 Graphite
		Grease) may be applied to tip
		threads.
5. Unit shuts off while welding and	a. See Problem 1.	a. Correct problems causing motor
“HXX” appears on display.		overload.
	b. Defective wire feed motor or	b. Replace.
	gearbox.
6. Drive roll does not turn although	a. Defective Wire Feed Unit to	a. Remove Wire Feed Unit to
arc voltage is present and	Control box cable or harnessing.	Control Box Cable and Check A
solenoid is on.		to A and B to B for continuity. If
		there is no continuity in either or
		both cases, replace cable.
		Otherwise, check Harnessing
		from A and B of MS connector on
		control box to control board and
		A and B at Wire Feed Unit MS
		connector to Motor leads for
		continuity. If harnessing is O.K.
		proceed to b.
	b. Defective wire feed motor or	b. Set Run-In speed to maximum.
	control PC board.	Disconnect wire drive plug P5
		from PC board. Measure voltage
		across pin 1(+) of J5 and pin 2 (-)
		of J5 on PC board with trigger
		closed. If voltage is > 24V DC,
		then replace motor assembly. If
		< 24V DC, replace Control PC
		board (see Procedure for
		Replacing PC Boards).

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