Lincoln Electric SVM166-A service manual Theory of Operation, Return to Section

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E-2	THEORY OF OPERATION	E-2
	FIGURE E.2 – GENERAL DESCRIPTION & INPUT POWER

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ELECTRODE INPUT VOLTAGE

TOROID

ASSEMBLY

FULL

WAVE

BRIDGE

CONTACTOR

	FEED	WELDING
	PLATE
GAS	M
SOLENOID	O	HALL
	T
"ELECTRODE"		EFFECT
	O
FEEDBACK	R	MODULE
VOLTAGE #67

ARMATURE

RPM FEEDBACK

ON/OFF

SWITCH

MOV

WORK SENSING LEAD

BOOST POWER SUPPLY BOARD

FEED HEAD BOARD SUPPLY

DRIVE MOTOR SUPPLY

FEED HEAD

CONTROL BOARD

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"WORK" VOLTAGE FEEDBACK #21

SPI COMMUNICATIONS

SHIELDED CABLE

COLD	WIRE	TRIGGER	TRIGGER	DISPLAY
		INPUT &	INTERLOCK
INCH	FEED			BOARD
		PROCEDURE	SWITCH
SWITCH	SPEED
	CONTROL

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GENERAL DESCRIPTION

The LN-15 is a lightweight portable semi-automatic wire feeder. The “Across the Arc” model is capable of operating with Lincoln DC power sources supplying between 15VDC to 110VDC. The LN-15 is designed for semi-automatic use and has a 60% duty cycle rat- ing.

By attaching the work clip to the work piece and the LN-15 electrode cable to the Lincoln power source the LN-15 is ready to feed wire and weld. The LN-15 can be connected for either welding polarity without any changes to the LN-15. When the gun trigger is acti- vated and wire feeds and an internal contactor ener- gizes the electrode output.

The wire drive is capable of operating in either the con- stant voltage or the constant current mode. A con- stant current voltage power source is recommended for flux-cored arc welding (FCAW) and gas metal arc welding (GMAW) to obtain code quality results.

For non-critical quality applications a constant current power source may be used.

The LN-15 comes factory equipped with a K1500-2 Tweco style #2-#4 gun bushing.

The “dual procedure” mode drops the wire feed speed 83% from the original set point. The voltage setting remains the same.

INPUT POWER

The DC voltage supplied from the power source is applied to the LN-15 through the electrode cable and the work sensing lead. The voltage is applied to the full wave bridge through a toroid assembly. When the ON/OFF switch is put in the ON position the positive DC voltage from the bridge is applied to the Boost/Power Supply board through an M.O.V. assem- bly. This M.O.V. is needed to protect the Boost/Power board from inductive energy stored in the welding cables.

The Boost/Power Board takes the weld voltage and boosts it to 80VDC or the actual arc voltage being applied. (Whichever is greater). The outputs of the Boost/Power board are two separate 80VDC+ supply voltages. One of these is utilized and regulated by the Feed Head Control board to power the wire drive motor. The other 80VDC supply is regulated to create several plus and minus regulated DC supplies. These +/-15VDC and +/-5VDC supplies are used to power the electronics within the Feed Head board and other components in the LN-15 such as the gas solenoid.

LN-15