Lincoln Electric SQUARE WAVE TIG 355 Service Manual page 48

E-4
FIGURE E.4 - HIGH VOLTAGE/HIGH FREQUENCY CIRCUIT
HIGH FREQUENCY SPARK
ELECTRODE SENSE
PANEL
SWITCHES
HIGH VOLTAGE
115VAC
TRANSFORMER
REMOTE
CIRCUIT
FEED - THRU
RECEPTACLE
BOARD
GAS/WATER
SOLENOIDS
115VAC
INTERLOCK
FANS 115VAC
RECEPTACLE
INPUT
R
CONTACTOR
E
C
O
N
N
E
C
T
START/
STOP
PILOT
TRANSFORMER
HIGH VOLTAGE /
HIGH FREQUENCY CIRCUIT
The control board signals the power board to pass the
115VAC voltage through the feed – thru board to the
primary of the high voltage transformer.
ondary of the high voltage transformer is coupled to a
spark gap generator and also to the high frequency
transformer. The high frequency transformer transfers
the high frequency "spark" to the electrode terminal.
THEORY OF OPERATION
UPPER LOWER
DISPLAY
CONTROL
CONTROL
BOARD
PANEL PANEL
SCR GATE COMMANDS
ELECTRODE
SENSE
15VDC
CONTROL
TRIGGER
BOARD
REMOTE INTERLOCK
COMMANDS
HI-FREQ/ WATER/GAS
COMMANDS
INTERLOCK
115VAC - HI-FREQ AND GAS/WATER
115VAC
CONTROL TRANSFORMER
115VAC
AC
AC
POWER
FACTOR
CAPACITORS
POLARITY
MAIN
TRANSFORMER
The sec-
NOTE: Unshaded areas of Block Logic
Diagram are the subject of discussion
SQUARE WAVE TIG 355
STATUS
BOARD
POWER
BOARD
SNUBBER
BOARD
DC-
C
H
DC+
O
K
E
BY-PASS
BOARDS
SWITCH
SHUNT
E-4
WORK
ELECTRODE
HI-FREQ
TRANSFORMER