E-4
E-4
PRECISION TIG 275
THEORY OF OPERATION
FIGURE E.4 – HIGH VOLTAGE / HIGH FREQUENCY CIRCUIT
POWER
SWITCH
RE
CO
NN
EC
T
P
AN
EL
OPTIONAL POWER
FACTOR
POLARITY
SWITCH
BYPASS BOARD
WORK
FRONT
ELECTRODE
REAR
ELECTRODE
78
V
AC
X1
X2
AC
AC
DC
DC
SHUNT
CH
O
KE
HIGH FREQUENCY
TRANSFORMER
HIGH VOLTAGE
TRANSFORMER
THERMOSTAT
115 VAC
115 VAC
11
5 V
AC
FAN
GA
TE
LE
AD
S
FE
ED
BA
CK
GAS
SOLENOID
11
5 V
AC
11
5 V
AC
LED's
THERMOSTAT
20 VAC
20 VAC
CONTROL BOARD
BACKGROUND
CIRCUIT
FROM
CONTROL
BOARD
63
.5
VA
C
CORRECTION
CAPACITORS
REAR GANG
SCR
BRIDGE
ADVANCED CONTROL
PANEL RECEPTACLE
MINIMUM
OUTPUT
CONTROL
MAXIMUM
OUTPUT
CONTROL
PROTECTION
BOARD
REMOTE
RECEPTACLE
METER
STICK
TIG
SWITCH
BALANCE
CONTROL
POST
FLOW
LOCAL/REMOTE
SWITCH
HIGH VOLTAGE/HIGH FREQUENCY
CIRCUIT
The control board passes the 115 VAC voltage to the
primary of the high voltage transformer. The secondary
of the high voltage transformer is coupled to a spark
gap generator and also to the primary winding of the
high frequency transformer. The secondary of the high
frequency transformer is in series with the rear elec-
trode output terminal. The high frequency “spark” is
present at the electrode terminal and is transferred to
the Tig torch.
NOTE:
Unshaded areas of Block Logic Diagram are the subject of discussion.
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