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TROUBLESHOOTING & REPAIR | ||
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POWER BOARD REMOVAL AND REPLACEMENT (continued)
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7.Using the 1/4”
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 Filter Capacitor Removal and Replacement.
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”
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.
18Inspect, clear and secure all leads in preparation for case
