High Voltage / High Frequency Circuit - Lincoln Electric SQUARE WAVE SVM141-A Service Manual

E-4
FIGURE E.4 – HIGH VOLTAGE / HIGH FREQUENCY CIRCUIT
INPUT
RECONNECT POWER
PANEL SWITCH
"A"
115VAC
RECEPTACLE
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 high frequency trans-
former. The high frequency transformer transfers the
high frequency "spark" to the electrode terminal, which
is coupled to the TIG torch.
NOTE: Unshaded areas of Block Logic Diagram are the subject of discussion.
THEORY OF OPERATION
MAIN
TRANSFORMER
H1
X1
H2
X2
H3
H4
23VAC
18VAC
18VAC
115VAC
FAN
REMOTE
RECEPTACLE
DOWNSLOPE
CONTROL
SQUARE WAVE TIG 275
BY-PASS
BOARD
POLARITY
SWITCH
C
H
O
AC DC+
K
SCR
E
BRIDGE
SHUNT
TRANSFORMER
DC-
AC
F
E
E
D
B
A
C
K
115VAC
CONTROL
BOARD
GAS POSTFLOW OUTPUT
BALANCE
VALVE CONTROL CONTROL
CONTROL
E-4
WORK
ELECTRODE
HI-FREQUENCY
TRANSFORMER
HIGH VOLTAGE
CIRCUIT
MODE
SWITCH
THERMAL
LIGHT
THERMOSTATS