TRIGGER AND INTERLOCK CIRCUIT The gun trigger (leads 602 & 604) is connected to the 24VAC circuit from the K350 Adapter, or the low voltage output control circuit (#2 & #4) of the power source if no K350 is required.
Once the trigger is closed the wire starts feeding. When the arc is estblished, the reed switch closes (leads 647 & 604) and the trigger is bypassed or “interlocked”. This feature allows the operator to release the trigger once the weld has begun to help eliminate fatigue.
The reed switch is a magnetically operated device that is mounted on a bracket above the block where the gun connects to the feeder. It responds to the magnetic field that is presnt due to the weld current flowing through the gun cable.
To stop welding, the operator must physically pull the gun away from the weld, thus stopping current flow and releasing the reed switch. See Figure E.3.

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E-3

 

 

 

 

 

THEORY OF OPERATION

 

E-3

 

 

 

 

 

 

FIGURE E.3 – CONTROL CIRCUITS.

 

 

WIRE SPEED CONTROL

 

 

 

 

 

 

 

 

 

 

 

 

REDUCED SPEED CONTROL

10KΩ, 4 W

 

 

 

 

 

567 521

 

 

 

 

A

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

R12

535

 

 

 

 

 

 

 

 

 

644

B

 

 

 

 

 

601

 

 

 

 

 

 

 

 

 

 

 

 

C

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

D

 

 

 

 

 

642

 

 

 

 

 

1

2

3

4

5

6

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

VOLTAGE CONTROL

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

10KΩ, 4 W

 

 

 

 

 

535

 

 

 

 

 

 

 

 

 

 

 

 

R75

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

75

 

 

 

 

 

LN-23P

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

539

 

 

 

 

 

 

 

 

 

76

 

 

 

 

 

CONTROL

 

 

 

 

 

 

 

647

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

77

 

 

 

 

 

P.C. BOARD

 

 

 

 

 

 

 

 

 

 

 

 

3.5 A CIRCUIT

 

 

 

 

 

 

 

 

 

 

541

 

W

 

 

 

 

 

BREAKER

 

 

 

 

 

 

 

 

 

 

100Ω, 1

R76

82V, 12J

604

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1

4

2

5

3

6

 

TP2

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

602

 

 

 

 

 

 

 

 

 

 

 

 

 

 

641

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

567A

67

642

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

567

521

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

BLACK

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

WHITE

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

WIRE FEED MOTOR

 

 

 

 

 

GUN TRIGGER SWITCH

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

604

 

C

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

B

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

602

 

A

8 PIN CONNECTOR

H

F

G

E

C

D

 

 

 

 

 

 

 

 

 

 

 

 

6 PIN CONNECTOR

F

E

D

C

B

A

 

 

 

 

 

 

 

 

 

 

 

 

77

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

604

 

75

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

647

 

76

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

REED SWITCH ACTIVATED

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

521

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

BY WELDING CURRENT

602

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

604

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ELECTRODE (-)

 

 

 

 

 

 

GUN CONDUCTOR BLOCK

 

WORK

 

WORK (+)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

21

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

VOLTS AND SPEED CONTROL CIRCUITS The Voltage Control is connected directly to the K350 Adapter or the power source (if no adapter is required) by leads 75, 76 & 77. It can be adjusted while welding to provide the voltage called for by the weld procedure.

The wire feed speed is controlled by signals to the Control Board from the Speed Control and the Reduced Speed Switch. The Wire Speed Control is calibrated and can be preset to the desired value. The speed will remain at the set value regardless of arc voltage as long as the Reduced Speed Switch is in Position 1 (open).

When the Reduced Speed Switch is in Position 2 (closed) the speed will be reduced to 83% of the set speed. This switch is to facilitate welding if the root opening changes or to reduce “sagging” of the weld metal as the operator approaches the bottom of a pipe joint. The switch may be changed to either position while welding as needed without stopping or breaking the arc.

NOTE: Unshaded areas of block logic diagrams are the subject of discussion.

LN-23P

Page 24 Page 26
Page 25
Image 25
Lincoln Electric SVM176-A service manual Figure E.3 Control Circuits
Page 24 Page 26

SVM176-A specifications

The Lincoln Electric SVM176-A is a robust and versatile semiautomatic wire feeder designed to cater to a wide range of welding applications. Known for its reliability and ease of use, the SVM176-A is particularly favored in both industrial and construction settings, where efficiency and performance are paramount.

One of the standout features of the SVM176-A is its compact design. This relatively lightweight unit is easy to transport and can fit into tight spaces, making it an ideal choice for mobile applications or projects that require more maneuverability. The unit's construction is durable and built to withstand the rigors of demanding work environments, ensuring longevity and consistent performance.

The SVM176-A supports various welding processes, including MIG (Metal Inert Gas) and flux-cored arc welding, providing versatility for different materials and thicknesses. This adaptability is enhanced by its ability to accommodate a variety of wire sizes, allowing users to select the ideal wire type for their specific project requirements. The equipment also features adjustable wire feed speed, helping to ensure optimal weld quality by allowing operators to tailor their settings based on the needs of the job.

Innovative technologies in the SVM176-A contribute to its performance. The unit is equipped with a digitally controlled microprocessor that streamlines operations, providing enhanced control over welding parameters. This advanced technology enables users to achieve precise welds consistently, minimizing the risk of defects and improving overall efficiency.

Another remarkable characteristic of the SVM176-A is its user-friendly interface. The unit features easy-to-read displays and intuitive controls, enabling operators to make quick adjustments without having to consult an extensive manual. This is particularly beneficial in fast-paced work environments where time is of the essence.

Furthermore, the Lincoln Electric SVM176-A boasts a range of safety features, including thermal overload protection and a sturdy casing, which safeguard both the equipment and the operator. With these characteristics combined, the SVM176-A stands out as a preferred choice for professional welders seeking reliability, versatility, and operational excellence in their equipment. This exceptional wire feeder continues to uphold Lincoln Electric's commitment to quality and performance in welding technology.
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