Troubleshooting & repair, Power board removal and replacement (continued) – Lincoln Electric INVERTEC V250-S User Manual
Page 79
F-47
TROUBLESHOOTING & REPAIR
F-47
7. Using the 1/4” nut-driver remove the
two screws holding the P.C. board to
the heat sink mounting bracket.
8. With the 3/16” Allen wrench remove
the four socket head cap screws and
washers holding the power board to
the large aluminum heat sink.
9. Carefully remove the power board
taking note as to the amount of heat
sink compound used between the
IGBTs and the large aluminum heat
sink. Note: Be sure to observe static
electricity precautions when handling
P.C. boards.
If the filter capacitors are to be
removed see
POWER BOARD REPLACEMENT
PROCEDURE
10. Apply a thin coat of Dow Corning
340 heat sink compound (Lincoln
E1868) to the filter capacitor termi-
nals. Do not apply to screw threads
or threaded area of terminals.
11. When replacing the power board
apply a thin coating (.005 to .010)
of Dow Corning 340 heat sink
compound (Lincoln E1868) to the
mating surfaces between the
IGBTs and the aluminum heat
sink. Compound is NOT permitted
on the screw heads or mounting
hole threads. The mating surfaces
must be clean and free of any for-
eign material.
12. Install the power board and tighten
the four cap head screws. Torque
the cap head screws to 40 to 48 IN.
Lbs. Note: Before tightening make
certain the capacitor terminals are
aligned with their respective holes
in the power P.C. board.
13. Assemble the leads #202A, #207A,
#203A and #206 to their respective
capacitor terminals using the bolts,
lockwashers and 7/16” wrench.
Torque to 50 - 60 IN. Lbs.
14. Using the 1/4” nut-driver install the
two screws holding the P.C. board
to the heat sink mounting bracket.
15. Connect leads #201, #204, #205,
#208, and #209 to their appropriate
terminals.
16. Replace plug J6 into power board.
17. Replace any previously removed
cable ties.
18 Inspect, clear and secure all leads
in preparation for case wrap-around
reassembly.
POWER BOARD REMOVAL AND REPLACEMENT (continued)
INVERTEC V250-S