Lincoln Electric SQUARE WAVE TIG 355 Service Manual page 115

F-63
SCR 3 & 4 Anode
and Negative Plate
SCR1 & 2
Cathode and
Positive Plate
TROUBLESHOOTING AND REPAIR
ACTIVE SCR TEST (continued)
FIGURE F.20 – SCR TEST POINTS
#4
Cathode
#1
Anode
SQUARE WAVE TIG 355
SCR3
SCR4
SCR1
SCR2
F-63
#3
Cathode
#2
Anode
Choke
Lead