Troubleshooting & repair, Switch board replacement (continued), Warning – Lincoln Electric INVERTEC SVM129-B User Manual

Page 98

TROUBLESHOOTING & REPAIR

F-60

INVERTEC® STT® & STT® II

SWITCH BOARD REPLACEMENT (continued)

FIGURE F.28 – SWITCH BOARD REMOVAL

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 following con-
ditions 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® & STT® II

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.

ELECTRIC SHOCK can
kill.

• Before continuing with the

test procedure, perform the
capacitor discharge proce-
dure to avoid electric
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.

WARNING

SOCKET
HEAD
SCREWS