Lincoln Electric SVM156-A service manual Replacement Procedure

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F-72	F-72
	TROUBLESHOOTING & REPAIR

OUTPUT RECTIFIER, STT CHOPPER BOARD AND RECTIFIER MODULE

REMOVAL AND REPLACEMENT (CONTINUED)

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7.Using the needle-nose pliers, remove leads #292 and #291 from the rectifier ther- mostat.

8.Disconnect plug J10 from the STT Chopper Board.

9.With the 7/16” wrench, remove lead #287 from the STT Snubber Diode D5.

10.With the 7/16” wrench, remove lead #289B from the STT Snubber Capacitor C10.

11.Using the 7/16” wrench, remove the four nuts and associated washers from the heat sink mounting bolts. The heat-sink assem- bly can be removed by carefully sliding the assembly forward and removing the mount- ing bolts.

4.Using the 3/16” allen wrench, remove the four screws and lock washers holding the board to the heat sink.

5.Carefully remove the STT Chopper Board.

REPLACEMENT PROCEDURE

1.Position the new board on the heat sink, using the standoffs for the slot head nylon screws and the allen head screws.

2.Install the four 3/16” allen head screws and lock washers.

3.Install the two nylon slot head screws.

4.Install the two 7/16” bolts, lock washers and flat washers.

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STT CHOPPER BOARD REMOVAL AND REPLACEMENT PROCEDURE

1.Place the output rectifier assembly on a clean bench surface.

2.Using a slot head screw driver, remove the two nylon screws holding the board to the heat sink. Save the standoffs for reassem- bly.

3.Using the 7/16” wrench, remove the two bolts, lock washers and flat washers. Save the standoffs for reassembly.

POWER WAVE 455/R