Lincoln Electric SVM157-A service manual Maintenance

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D-2	MAINTENANCE		D-2
SAFETY PRECAUTIONS		CONTACT TIP AND GAS NOZZLE
		INSTALLATION
	WARNING
		1. Choose the correct size contact tip for the electrode
		being used (wire size is stenciled on the side of the
	ELECTRIC SHOCK can kill.
		contact tip) and screw it snugly into the gas diffuser.
	• Have an electrician install and	2. Screw the appropriate fixed gas nozzle fully onto
	service this equipment.
		the diffuser. Either the standard .50" (12.7 mm)
	• Turn the input power off at the
		flush nozzle or other optional flush or recessed
	fuse box before working on	(spray arc) nozzle sizes may be used. (See Table
	equipment	D.2 in this section.)
	• Do not touch electrically hot	3. If using optional adjustable slip-on nozzles, see
	parts.
		Table D.2 in this section.
(READ THE SAFETY PRECAUTIONS IN		• Be sure the nozzle insulator is fully screwed onto
THE FRONT OF THIS MANUAL BEFORE		the gun tube and does not block the gas holes in
WORKING ON THIS MACHINE.)		the diffuser.
GENERAL MAINTENANCE		• Slip the appropriate gas nozzle onto the nozzle
		insulator. Either a standard .50" (12.7 mm) or
In extremely dusty locations, dirt may clog the air pas-		optional .62" (15.9 mm) I.D. slip-on gas nozzle
sages causing the welder to run hot. Blow dirt out of		may be used and should be selected based on
the welder with low-pressure air at regular intervals to		the welding application.
eliminate excessive dirt and dust build-up on internal
parts.		* Adjust the gas nozzle as appropriate for the
		GMAW process to be used. Typically, the con-
The fan motors have sealed ball bearings which		tact tip end should be flush to .12" (3.2 mm)
require no service.		extended for the short-circuiting transfer process
		and .12" (3.2 mm) recessed for spray transfer.

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DRIVE ROLLS AND GUIDE PLATES

After every coil of wire, inspect the wire drive mecha- nism. Clean it as necessary by blowing with low pres- sure compressed air. Do not use solvents for cleaning the idle roll because it may wash the lubricant out of the bearing. All drive rolls are stamped with the wire sizes they will feed. If a wire size other than that stamped on the roll is used, the drive roll must be changed.

For instructions on replacing or changing drive roll, see “Wire Drive Rolls” in Operation section.

GUN TUBES AND NOZZLES

1.Replace worn contact tips as required.

2.Remove spatter from inside of gas nozzle and from tip after each 10 minutes of arc time or as required.

GUN CABLE CLEANING

To help prevent feeding problems, clean cable liner after using approximately 300 pounds (136 kg) of elec- trode. Remove the cable from the wire feeder and lay it out straight on the floor. Remove the contact tip from the gun. Using an air hose and only partial pressure, gently blow out the cable liner from the gas diffuser end.

POWER MIG 200