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G-11
ELECTRICAL DIAGRAMS
SQUARE WAVE TIG 255
CONTROL BOARD SCHEMATIC — SQUARE WAVE TIG 255
(G2150)
D46
100
R14
1.00K
R113
+15V
IOGND
J5
1
SCR GATE
100V
1A
Q6
J5
3
J8
11
16VAC
AUX SCR3
AUX SCR3
windings )
( 1 of 5 XFMR
secondary
J8
5
SCR CATHODE
1.00K
R118
3
3
475K
R116
CNY17-3
OCI6
42
1
6
5
267
R64
+15V
SCR GATE
1W
18V
DZ5
1W
30V
DZ6
1.00K
R112
475K
R16
J5
8
D43
267
R181
1.00K
R20
D44
D45
D48
D50
1W
18V
DZ4
D52
1.00K
R25
J5
6
CNY17-3
OCI3
42
1
6
5
40V
600mA
Q5
100
R168
100
R182
D47
27
35V
C27
1.00K
R115
1.0
35V
C47
1.0
35V
C48
1000
35V
C42
D99
20
50V
C43
D73
D71
D92
D100
D23
1W
12V
DZ17
D72
4.7
35V
C66
4.75K
R42
74HC573
X20
20
10
D4
X10
11
10
50V
0.1
C3
S18647-2
10K
R223
10K
R211
X10
13
12
X10
5
6
D24
D2
10K
R224
+15V
NGND
-15V
NGND
LCDGND
NGND
IO+5V
N+5V
IOGND
LGNDNGND
IOGND
7815
7805
7915
Vss
Vdd
MC68HC11
X3
1
26
GND
IN
OUT
X12
D101
475K
R200
40V
600mA
Q1
4.7
35V
C65
C41
1W
12V
DZ15
100K
R199
OUT
IN
GND
X16
GND
IN
OUT
X15
D25
CAPACITORS =
UNLESS OTHERWISE SPECIFIED)
.022/50V
DIODES =
1A, 400V
01/03/94
(UNLESS OTHERWISE SPECIFIED)
SQUARE WAVE TIG 255 CONTROL BOARD
1/4W
(
MFD
GENERAL INFORMATION
UNLESS OTHERWISE SPECIFIED)
RESISTORS = Ohms (
33074A
X14
4
11
X32_+5V
X31_+5V
IOGND
+15V
50V
0.1
C14
TCF6000
X32
8
1
50V
0.1
C15
X32GND
X31GND
IOGND
IOGND
-15V
TCF6000
X31
8
1
50V
0.1
C12
50V
0.1
C11
33074A
X11
4
11
50V
0.1
C70
NGND
221K
R27
100K
R39
47.5K
R40
47.5K
R30
50V
0.1
C81
47.5K
R32
J6
12
X11
14
12
13
1000V
750p
C79
1W
12V
DZ16
1W
12V
DZ14
3000V
.0047
C49
47.5K
R29
1N4007
D11
47.5K
R31
1N4007
D22
47.5K
R28
1N4007
D21
1N4007
D10
D30
1.00K
R69
100K
R44
1.00M
R55
J6
5
1.00M
R38
1000V
750p
C80
D5
J8
1
J8
2
3000V
.0047
C67
X32
7
X31
7
X31
6
VB
NGND
Voltage FB
ELECTRODE
WORK
36VAC CT
16VAC
16VAC
16VAC
36VAC C.T.
24VAC
120VAC
CONTROL TRANSFORMER
D53
100
R24
D49
1.00K
R226
40V
600mA
Q3
X10
1
2
1.00K
R225
475K
R136
100
R169
J8
6
D77
J8
12
40V
600mA
Q16
CNY17-3
OCI4
42
1
6
5
100
R21
15.0K
R137
X10
3
4
267
R184
267
R23
267
R185
40V
600mA
Q17
DISPLAY COMMON
LGND
X31GND
NOISY COMMON
NGND
IOGND
X31 COMMON
PROCESSOR IO COMMON
X32 COMMON
LEGEND
(GROUND AND +5V NETS)
LCDGND
LOGIC COMMON
X32GND
PROCESSOR IO+5V SUPPLY
X31 +5V SUPPLY
NOISY+5V SUPPLY
L+5V
X32_+5V
N+5V
LCD+5V
X32 +5V SUPPLY
DISPLAY +5V SUPPLY
LOGIC +5V SUPPLY
IO+5V
X31_+5V
D51
475K
R19
2.21K
R134
D54
IOGND
IO+5V
LCD+5V
X31GND
IO+5V
IO+5V
IOGND
IOGND
X31_+5V
IOGND
L+5V
10K
R22
100V
1A
Q4
1W
30V
DZ7
27
35V
C29
+15V
27
35V
C28
SCR CATHODE
1
1
windings )
( 1 of 5 XFMR
secondary
AUX SCR1,2
+15V
100V
1A
Q2
AUX SCR1,2
475K
R65
16VAC
1W
18V
DZ8
267
R12
100
R26
CNY17-3
OCI5
42
1
6
5
D76
100
R170
1.00K
R114
J5
7
J5
2
100
R183
D58
1W
30V
DZ10
D59
100K
R67
16VAC
D1
D6
D7
J8
10
J5
4
D55
J8
4
1.00K
R120
D56
D57
100
R171
1W
30V
DZ1
1W
18V
DZ9
100
R18
100V
1A
Q12
J5
9
100
R17
AUX SCR4
SCR CATHODE
windings )
( 1 of 5 XFMR
secondary
AUX SCR4
SCR CATHODE
4
4
SCR GATE
2
2
SCR GATE
27
35V
C30
VOLT_FB
CT
.1
50V
C38
2.21K
R212
windings )
( 1 of 5 XFMR
secondary
50V
0.1
C69
X31
5
X11
1
3
2
-15V
NGND
74HC573
X22
20
10
221K
R63
.1
50V
C45
10K
R9
NGND
X32GND
X32_+5V
LGND
LGNDLGNDLGND
50V
0.1
C10
74HC573
X21
20
10
50V
0.1
C7
1.0
35V
C44
X10
98
1.00K
R214
IOGND
L+5V
X10
74HC14
7
14
ZERO CROSS
J8
7
3000V
.0047
C68
D3
A
VOLTAGE FEEDBACK
ZERO CROSS
SCR 2,4
SCR 1,3
A482.1
TO A482.2
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NOTE: Lincoln Electric assumes no responsibility for liabilities resulting from board level troubleshooting. PC Board
repairs will invalidate your factory warranty. This Printed Circuit Board schematic is provided for reference only. It may not
be totally applicable to your machine's specific PC board version. This diagram is intended to provide general information
regarding PC board function. Lincoln Electric discourages board level troubleshooting and repair since it may compromise
the quality of the design and may result in Danger to the Machine Operator or Technician. Improper PC board repairs
could result in damage to the machine.