Theory of operation, High voltage/high frequency circuit, Precision tig 275 – Lincoln Electric PRECISION TIG 275 SVM162-B User Manual

Page 42: Figure e.4 – high voltage / high frequency circuit, Control board

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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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