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TOC
THEORY OF OPERATION | ||
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FIGURE E.5 — TRIGGER, GAS SOLENOID & WIRE DRIVE
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ARC
VOLTAGE
CONTROL
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| BREAKER | SWITCH |
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INPUT |
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RECEPTACLE |
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TRIGGER | WIRE | |
RECEPTACLE | SPEED | |
| CONTROL | |
CONTROL | GAS | |
BOARD | ||
SOLENOID | ||
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| WIRE | |
| FEED | |
| MOTOR | |
| VOLTAGE FEEDBACK & | |
| MOTOR POWER |
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MAIN |
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TRANSFORMER |
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CHOKE
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OUTPUT
TERMINALS
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TRIGGER, GAS SOLENOID AND WIRE DRIVE
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Closure of the trigger circuit (pulling the gun trigger) signals the control board to start several functions. A DC is applied to the gas solenoid (if present) to allow shielding gas to flow if required. The SCRs are acti- vated and voltage is applied to the main transformer.
The output voltage that is developed at the output ter- minals is also fed back to the control board to facilitate control of the output and also to power the Wire feed Motor circuitry.
The voltage that powers the wire drive motor is varied and controlled on the control board in response to the setting of the Wire Speed Control. The control board monitors the drive motor armature current and voltage and compares the feedback information with the com- mands sent from the wire speed control to maintain a constant wire speed.
The Control Board also has an automatic protection circuit, which shuts off the trigger circuit in the event of a wire drive motor overload.
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NOTE: Unshaded areas of Block Logic Diagram are the subject of discussion
