G-12
ELECTRICAL DIAGRAMS
SQUARE WAVE TIG 255
CONTROL BOARD SCHEMATIC — SQUARE WAVE TIG 255 (cont’d)
(G2150)
N + 5 V
L G N D
R O W 5
1 3 0
8 . 0 M H z
Y1
1.00M
R71
1K
R87
1 0 0 V
2 2 p
C 2 2
4.75K
R81
4.75K
R210
1.0
3 5 V
C 2 3
C 2 0
G N D
R E S
IN
X 1 9
5 0 V
0.1
C 3 3
C 5
J 6
10
+ 1 5 V
4 7 5
R83
D 3 9
D 3 4
I O G N D
18
1 5 V
C 1 6
D 7
L + 5 V
J 6
11
J 6
3
D 0 - D 7
D 4
D 6
C 2 5
D 5
D 0
1K
R84
D 3
X 3 2
4
1.00K
R140
D1
D 2
1 0 0 V
2 2 p
C 3 2
4.75K
R48
L G N D
X 3 2
6
5 0 V
1 5 0 p
C 1 9
C N Y 1 7 - 3
O C I 2
4
2
1
6
5
X 3 2
3
475K
R70
R O W 4
4.75K
R79
4.75K
R132
X 3 2
2
C R Y S T A L
N O T U S E D
P E 4
R E S E T
L E D L A T C H E N A B L E
D I S P L A Y L A T C H E N A B L E
M I S C . L A T C H E N A B L E
L A T C H O U T P U T E N A B L E
R E F
A / D
P C 1
N O T U S E D
X I R Q
R O W 3
X 3 2
5
D 8 0
+ 1 5 V
I O + 5 V
N + 5 V
C O L 3
C O L 4
K E Y P A D
C O L 2
C O L 1
A C / D C M I C R O S W I T C H
R O W 1
A R C S T A R T S W I T C H
R O W 2
R O W 1
R O W 5
R O W 3
R O W 2
R O W 4
O C 4
M O D A
N O T U S E D
N O T U S E D
N O T U S E D
N O T U S E D
P E 6
J 2
5
1 0 0 V
1 0 0 p
C 8 4
1 0 0 V
1 0 0 p
C 8 6
10K
R187
475K
R43
1 0 K
R76
5 0 V
1 5 0 p
C 2 1
C N Y 1 7 - 3
OCI1
4
2
1
6
5
1.00K
R129
1 0 0 V
1 0 0 p
C 8 5
26.7K
R233
J 8
9
J 6
4
J 8
3
1.50K
R72
1.50K
R85
4 7 5
R82
D 4 0
D 1 9
4 7 5
R73
C 3 4
D 3 7
D 3 8
D 7 9
D 2 0
18
1 5 V
C 3 5
D 1 8
1K
R74
4 7 5
R75
J 2
6
J 2
4
J 2
2
4 0 V
6 0 0 m A
Q11
J 2
8
1 0 0 V
1 0 0 p
C 8 2
1 0 0 V
1 0 0 p
C 8 3
D 7 8
D 8 1
1.00K
R77
+
t
5 6
P T C 2
J 2
9
J 2
1
26.7K
R231
26.7K
R232
J 2
7
1.00K
R124
1.00K
R57
26.7K
R230
1.00K
R127
1.00K
R123
J 2
3
26.7K
R234
4.75K
R215
1
2 6
M O D B
IC1
V s s
P C 5
V d d
X 3
P E 2
E X T A L
P C 7
P C 6
P D 3
P A 7
P A 0
P A 1
V R H
P C 0
I R Q
P D 4
P D 1
P E 0
V R L
P D 0
X T A L
P E 3
P E 5
O C 2
P D 5
O C 3
M C 6 8 H C 1 1
P D 2
P E 7
O C 5
P C 2
R E S E T
P E 1
18
3 2
4 9
4 3
4 5
2 9
19
2 4
2 2
3 3
5 0
15
16
2 0
2 3
2 8
21
2 5
4 7
2 7
3 5
3 6
3 4
3 7
3 8
3 9
31
3
4 0
4 2
12
41
5
6
4
13
4 8
4 6
3 0
4 4
2
17
51
9
7
8
10
11
14
5 2
D 0
D 4
D1
D 3
D 2
D 5
D 6
P B 6
P B 4
4.75K
R208
S T R B / R / W
4.75K
R207
4.75K
R204
4.75K
R216
4.75K
R218
4.75K
R201
4.75K
R203
4.75K
R205
4.75K
R206
4.75K
R217
4.75K
R202
R E M O T E C U R R E N T
P B 5
D 0 - D 7
P B 7
P C 3
P C 4
J1
5
J1
7
1.00K
R 9 1
J1
3
D 2
Q 0
D 7
L E
D 0
Q 2
Q1
D 5
D 6
Q 3
Q 4
Q 5
Q 6
Q 7
O E
7 4 H C 5 7 3
D 4
D1
D 3
X 2 0
12
1
16
19
2
6
15
9
11
4
8
3
7
5
17
18
13
14
1.00K
R 9 3
1.00K
R 9 2
L G N D
J1
1
1.00K
R 9 4
J1
6
P B O
N O T U S E D
N O T U S E D
N O T U S E D
P B 3
P B 2
P B 1
E C L O C K
N O T U S E D
J1
4
J1
2
D 7
D 0 - D 7
N O T U S E D
S T R A / A S
D41
X 1 4
14
12
13
3 0 1
R 3 3
1 0 0
R 1 5 4
1 0 0
R 1 6 0
1 0 0
R 1 5 7
1 0 0
R 1 5 9
1 0 0
R 1 5 5
1 0 0
R 1 5 6
1 0 0
R 1 5 8
L C D C O N T R A S T T E M P E R A T U R E C O M P E N S A T I O N C I R C U I T
T P 2
1 0 0 K
R 2 3 6
X 1 4
7
5
6
1 3 3 K
R 7
3 . 3 2 K
R 8 8
J1
8
1 0 0
R 1 0 9
M I C R O S W I T C H
24VAC
windings )
( 1 o f 5 X F M R
s e c o n d a r y
S W I T C H
A R C S T A R T
A C / D C
+
1 0 K
-
C O N T R O L
P O T
R E M O T E
S H U N T
4 0 0 A / 2 0 0 m V
1 5 0
R 5 2
J 7
1
2 2 1 K
R142
+
t
5 6
P T C 1
J 6
1
26.7
R 1 3 8
3 3 . 2 K
R141
26.7
R 1 3 9
1 0 K
R49
1 5 0
R 5 1
J 7
2
1.00K
R56
4 . 7 5 K
R 6 6
1.0
3 5 V
C 7 1
N G N D
C 7 6
4 . 7 5 K
R 5 3
1.00M
R54
N G N D
J 6
8
N + 5 V
N G N D
J 6
2
4 0 V
6 0 0 m A
Q 1 4
4 0 V
6 0 0 m A
Q 8
4 0 V
6 0 0 m A
Q 1 3
1 0 K
R 1 7 2
1 0 K
R 1 2 2
1 0 K
R 1 2 8
H I G H
F R E Q
W A T E R
J 4
3
G A S
115V
G
M T 2
M T 1
T R I 2
J 4
1
2 6 7
R 1 0 8
G
M T 2
M T 1
T R I 3
4 7 5
R 1 0 4
4 7 5
R 1 0 3
1.00K
R 2 2 8
G
M T 2
M T 1
TRI1
O C I 9
2
6
1
4
O C I 8
2
6
1
4
J 4
2
2 6 7
R 1 0 7
1.00K
R 2 2 7
I O G N D
L + 5 V
I O + 5 V
I O G N D
N G N D
N G N D
N G N D
N G N D
N G N D
1 0 K
R 1 2 5
J 4
5
4 7 5
R 1 0 2
2 6 7
R 1 0 6
D 0
5 0 V
0.1
C 7 8
X 3 1
4
L G N D
D 4
D 6
D 3
D 2
D1
D 7
D 0 - D 7
D 5
1.00K
R 6 8
L C D G N D
J 3
8
J 3
14
R / W
1 0 0
R 1 6 2
1 0 0
R 1 6 3
5 0 V
0.1
C 6 2
1 0 0 V
1 0 0 p
C 5 7
4 . 7 5 K
R131
1.0A
3 0 V
D 4 2
4 . 7 5 K
R 1 3 0
X 1 4
8
10
9
3 . 3 2 K
R 1 6 6
1 0 0 V
1 0 0 p
C 5 2
J 3
7
J 3
5
3 . 3 2 K
R 1 6 7
J 3
6
J 3
4
J 3
3
J 3
11
J 3
10
J 3
13
J 3
15
J 3
16
3.32K
R150
1 0 0 V
1 0 0 p
C 5 8
1 0 0 V
1 0 0 p
C 5 4
1 0 0 V
1 0 0 p
C 5 6
1 0 0 V
1 0 0 p
C 5 9
1 0 0 V
1 0 0 p
C 5 3
1 0 0 V
1 0 0 p
C 5 1
1 0 0 V
1 0 0 p
C 6 0
1 0 0 V
1 0 0 p
C 5 5
L C D G N D
L C D G N D
L C D G N D
D 7
D 6
D 3
D 2
D 4
D1
D 5
T P 1
T P 3
L C D C O N T R A S T C I R C U I T
D I S P L A Y
L C D
V D D
R S
V o
V S S
E
4 . 7 5 K
R 9 7
J 3
12
3.32K
R153
3.32K
R147
3.32K
R148
3.32K
R151
3.32K
R152
3.32K
R149
J 3
9
J 3
2
J 3
1
D 7 4
4 0 V
6 0 0 m A
Q 1 0
. 3 9 m H
L 3
5 W
1 5 0
R 2 3 5
5 W
1 5 0
R 1 6 4
100K
R222
+ 1 5 V
D 2
Q 0
D 7
L E
D 0
Q 2
Q1
D 5
D 6
Q 3
Q 4
Q 5
Q 6
Q 7
O E
7 4 H C 5 7 3
D 4
D1
D 3
X 2 1
12
1
16
19
2
6
15
9
11
4
8
3
7
5
17
18
13
14
D 0
_
P I E Z O
B U Z Z E R
1.00K
R 2 2 9
OCI10
2
6
1
4
115V
LED(+)
J 4
4
. 3 9 m H
L 2
+
J 6
6
J 6
13
D 7 5
LED(-)
I O G N D
I O G N D
I O G N D
I O G N D
L C D + 5 V
N G N D
V B
I O G N D
HI_
N G N D
X 1 4
1
2
3
C 7 3
L O _
1.00K
R 1 4 4
R E M C U R
5 0 V
0.1
C 7 5
2.21K
R 5 0
1.00K
R 4 1
1 W
1 2 V
D Z 1 3
X11
8
9
10
C 7 4
C U R _ F B
5 0 V
0.1
C 7 2
C U R _ F B
X 3 1
2
N G N D
I O G N D
I O G N D
X11
7
6
5
N G N D
N G N D
C 7 7
3 . 3 2 K
R 1 4 3
X 3 1
3
I O G N D
D 0
M T
1 0 K
C W
R237
D 2
D 6
D 4
D1
D 7
D 3
D 5
L G N D
2 . 6 7 K
R 3 4
2.21K
R101
. 3 3 m H
L1
L O W C U R R E N T F E E D B A C K
4.75K
R213
4.75K
R209
H I G H C U R R E N T F E E D B A C K
S C R 2 , 4
Z E R O C R O S S
S C R 1 , 3
D I S P L A Y E
V O L T A G E F E E D B A C K
N O T U S E D
N O T U S E D
N O T U S E D
D I S P L A Y R S
D 2
Q 0
D 7
L E
D 0
Q 2
Q1
D 5
D 6
Q 3
Q 4
Q 5
Q 6
Q 7
O E
7 4 H C 5 7 3
D 4
D1
D 3
X 2 2
12
1
16
19
2
6
15
9
11
4
8
3
7
5
17
18
13
14
3.32K
R146
L C D G N D
L C D G N D
L C D G N D
-15V
L C D + 5 V
VOLTAGE FEEDBACK
ZERO CROSS
SCR 2,4
SCR 1,3
C A P A C I T O R S =
U N L E S S O T H E R W I S E S P E C I F I E D )
. 0 2 2 / 5 0 V
D I O D E S =
1A, 400V
0 1 / 0 3 / 9 4
( U N L E S S O T H E R W I S E S P E C I F I E D )
S Q U A R E W A V E T I G 2 5 5 C O N T R O L B O A R D
1 / 4 W
(
M F D
G E N E R A L I N F O R M A T I O N
U N L E S S O T H E R W I S E S P E C I F I E D )
R E S I S T O R S = O h m s (
A
A 4 8 2 . 2
T O A 4 8 2 . 1
D I S P L A Y C O M M O N
L G N D
X 3 1 G N D
N O I S Y C O M M O N
N G N D
I O G N D
X 3 1 C O M M O N
P R O C E S S O R I O C O M M O N
X 3 2 C O M M O N
L E G E N D
( G R O U N D A N D + 5 V N E T S )
L C D G N D
L O G I C C O M M O N
X 3 2 G N D
P R O C E S S O R I O + 5 V S U P P L Y
X 3 1 + 5 V S U P P L Y
N O I S Y + 5 V S U P P L Y
L + 5 V
X 3 2 _ + 5 V
N + 5 V
L C D + 5 V
X 3 2 + 5 V S U P P L Y
D I S P L A Y + 5 V S U P P L Y
L O G I C + 5 V S U P P L Y
I O + 5 V
X 3 1 _ + 5 V
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.
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