Lincoln Electric SVM153-A service manual Diode Module Removal, Diode Module Replacement

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F-69	F-69
	TROUBLESHOOTING & REPAIR

POWER MODULE (CHOPPER) PC BOARD/DIODE

MODULE REMOVAL AND REPLACEMENT (CONTINUED)

FIGURE F.31 – DIODE MODULE MOUNTING DETAILS AND TIGHTENING SEQUENCE

2 TO 3 TURNS EACH

12-18 IN.LBS.

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SPRING WASHER

PLAIN WASHER

5.0-10 IN-LBS.

FINGER TIGHT

5.0-10 IN-LBS.

30-40 IN.LBS.

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DIODE MODULE REMOVAL

Refer to Figure F.31.

1.Remove the Power Module PC board as described above.

2.Using the 7/16" wrench, remove the two outer screws, spring washers, and large flat washers from the diode module.

3.Using the 9/64" allen wrench, remove the set screw from the center of the diode module.

4.Remove the diode module from the heat sink.

DIODE MODULE REPLACEMENT

Refer to Figure F.31.

CAUTION

The proper tightening sequence is required to mount the diode module to the heat sink in order to avoid warping the base plate. Apply the proper torque to all fasteners.

1.Be sure the heat sink mounting surface is clean, dry, and free of grease.

2.Apply a thin, even coat (.1 to .25mm or .004 to .010 in) of Penetrox A13 thermal joint compound (T12837-1) to the diode module base plate only, under the plastic body of the module. Do not apply compound to the area under the mounting holes.

3.Press the module firmly against the heat sink, aligning the mounting holes.

4.Place a spring washer then a flat washer over each outer mounting screw and insert them into the holes. Insert the allen head screw into the center hole. Tighten all three screws 2 – 3 turns each, finger-tight only (1).

5.Using the torque wrench and 7/16" socket, tighten each outer screw between 5.0 and 10 in-lbs (2).

6.Using the torque wrench and 9/64" allen head socket, tighten the center screw between 12 and 18 in-lbs (3).

7.Now tighten the two outer screws between 30 and 40 in-lbs (4).

8.Replace the Power Module PC board as described above.

COMMANDER 500