Lincoln Electric INVERTEC SVM129-B Service Manual page 98

F-60
SWITCH BOARD REPLACEMENT (continued)
PROCEDURE
NOTE: If a test indicates that a switch board is
defective, both switch boards must be replaced at
the same time. In addition to replacing the switch
boards, replace capacitors C1 and C2 if the fol-
lowing conditions exist:
a. The machine was operating from 380 VAC
or higher when the failure occurred.
b. Burned areas are visible on the switch
boards.
1. Turn off the Invertec STT and disconnect main
AC input power to the machine.
2. Using the 5/16" nut driver, remove the case
wraparound cover.
3. Perform the Input Filter Capacitor Discharge
Procedure. See the Maintenance section.
TROUBLESHOOTING & REPAIR
FIGURE F.28 – SWITCH BOARD REMOVAL
INVERTEC STT
SOCKET
HEAD
SCREWS
WARNING
ELECTRIC SHOCK can kill.
• Before continuing with the
test procedure, perform the
capacitor discharge proce-
dure
shock.
4. Carefully disconnect the leads at the top of the
switch board.
5. Using the 3/16" socket wrench, remove the
four cap screws from the switch board. See
Figure F.28.
F-60
to avoid electric