THEORY OF OPERATION | ||
| FIGURE E.2 – GENERAL DESCRIPTION AND INPUT POWER CIRCUIT |
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CONTROL
BOARD
OPTIONAL POWER
CORRECTIONFACTOR
CAPACITORS
POWER
BACKGROUND
CIRCUIT
63.5 VAC
REAR GANG | WORK |
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POLARITY
SWITCH
BYPASS BOARD
FRONT ELECTRODE
HIGH FREQUENCY
SWITCH
PANEL
RECONNECT
X1
VAC78 X2
AC | DC | CHOKE |
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| SCR |
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BRIDGE |
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AC | DC | SHUNT |
TRANSFORMER
HIGH VOLTAGE TRANSFORMER
REAR ELECTRODE
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| THERMOSTAT | LEADSGATE FEEDBACK | SOLENOID | 115 | |||||
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| VAC |
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| 115 VAC | 115 |
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20 VAC
20 VAC
MINIMUM
OUTPUT
CONTROL
CONTROL BOARD
ADVANCED CONTROL
PANEL RECEPTACLE
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| PROTECTION |
| METER |
| STICK |
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| BOARD |
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| TIG |
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| SWITCH |
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| BALANCE | POST | LOCAL/REMOTE | |||||
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| CONTROL | FLOW |
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THERMOSTAT
LED's
Return to Section TOC Return to Master TOC
Return to Section TOC Return to Master TOC
Return to Section TOC Return to Master TOC
Return to Section TOC Return to Master TOC
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| MAXIMUM |
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| OUTPUT | REMOTE |
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GENERAL DESCRIPTION | CONTROL |
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| turned “on,” the input voltage is applied directly to the | ||||
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| RECEPTACLE |
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The PRECISION TIG 275 is part of a new family of | the reconnect panel. When the input power switch is | ||||
primary winding of the main transformer. |
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industrial arc welding power sources able to provide | The main transformer changes the high voltage, low | ||||
constant current and single range square wave AC/DC | |||||
Tig (GTAW) with new MicroStartTM Technology. It incor- | current input power to a low voltage, high current out- | ||||
porates independent presettable minimum and maxi- | put available at the main secondary winding (X1 and | ||||
mum output control with | X2). This 78 VAC winding supplies power to the weld- | ||||
lization for continuous AC Tig welding and reliable DC | ing arc. In addition, four auxiliary windings are incor- | ||||
Tig starting. The Precision TIG 275 also has AC/DC | porated in the main transformer. The 115 VAC winding | ||||
stick (SMAW) capabilities. This new design includes | supplies power to the 115 VAC receptacle. | Through | |||
advanced features such as a digital meter, presettable | the control board, it also powers the gas solenoid, the | ||||
controls, auto balance | TM | , fan as needed and timers for | high voltage transformer, and the cooling | fan. The | |
| cooling fan is activated only when welding current is | ||||
fixed preflow and variable post flow of shielding gas. It | sensed. The 63.5 VAC winding provides power for the | ||||
features a stick output terminal (front) and a universal | DC background current. This circuit is active in the DC | ||||
Tig torch connection box (rear) for simultaneous, but | TIG welding mode. The 20 VAC windings are included | ||||
separate, electrode outputs. |
| in the main transformer assembly. The 20 VAC winding | |||
INPUT POWER CIRCUIT |
| ger circuitry. The other 20 VAC winding is used by the | |||
The desired | is rectified on the control board and is used in the trig- | ||||
control board for phase detection. This AC voltage is | |||||
the PRECISION TIG 275 through the power switch to | also rectified to several DC voltages and regulated to | ||||
the reconnect panel located in the rear of the machine. | +15 VDC and +5 VDC power supplies that operate the | ||||
The machine can be configured for any one of three | circuitry on the control board. |
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input voltages (208 VAC, 230 VAC or 460 VAC) by con- |
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necting the jumper strap to the appropriate terminal on |
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NOTE: Unshaded areas of Block Logic Diagram are the subject of discussion.
PRECISION TIG 275
