Lincoln Electric PRECISION TIG 275 SVM162-B - Manual (Page 39)

Return
to
Master
TOC
Return
to
Master
TOC
Return
to
Master
TOC
Return
to
Master
TOC
E-1 E-1
PRECISION TIG 275
Theory of Operation..............................................................................................................Section E
General Description ....................................................................................................................E-2
Input Power Circuit......................................................................................................................E-2
Output Rectification, Control Board and Feedback ....................................................................E-3
High Voltage/High Frequency Circuit..........................................................................................E-4
DC Welding Output .....................................................................................................................E-5
AC Welding Output .....................................................................................................................E-6
SCR Operation............................................................................................................................E-7
Protective Circuits .......................................................................................................................E-8
Fan As Needed (F.A.N.)........................................................................................................E-8
Thermal Protection ...............................................................................................................E-8
Overload Protection..............................................................................................................E-8
TABLE OF CONTENTS
-THEORY OF OPERATION SECTION-
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
FIGURE E.1 – PRECISION TIG 275 BLOCK LOGIC DIAGRAM