PRECISION TIG 185
THEORY OF OPERATION
E-2 E-2
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INPUT POWER CIRCUIT
The desired single-phase input power is connected to
the TIG 185 through an input power switch located in
the front panel of the machine. The machine can be
configured for either 230VAC or 208VAC input voltage
by connecting the appropriate lead (H2 or H3) to the
input power switch. When the input power switch is
turned “ON” the input voltage is applied directly to the
primary of the main transformer.
The main transformer changes the high voltage, low
current input power to a low voltage, high current out-
put which is available at the main secondary winding
(X1 and X2). In addition three auxiliary windings are
incorporated in the main transformer. The 115VAC
winding supplies power to the fan motor and also,
through the control board, powers the gas solenoid
valve and the high voltage transformer. The 18VAC
winding provides power to the trigger circuitry. The
other 18VAC winding is rectified and regulated to a
15VDC supply which operates the circuitry on the con-
trol board.
FIGURE E.2 Main Transformer and Input Power
NOTE: Unshaded areas of block logic diagrams are the subject of discussion.
GENERAL DESCRIPTION
The PRECISION TIG 185 is a member of our field
acclaimed Precision TIG family of industrial arc weld-
ing power sources. Premium features include:
1. Precise constant current output.
2. Full range square wave AC/DC TIG (GTAW) weld-
ing.
3. Enhanced version of the patented MicroStart
TM
Technology for its lower Minimum (5amps) to high-
er Maximum (185 amps) output control range.
4. Built-in high frequency stabilization for DC TIG
starting and continuous AC TIG welding.
5. AC/DC Stick (SMAW capability.)
