Lincoln Electric SVM100-A service manual SCR Heat Sink Assembly Removal

Return to Section TOC

Return to Section TOC

Return to Master TOC

Return to Master TOC

F-43 TROUBLESHOOTING & REPAIR

SCR HEAT SINK ASSEMBLY REMOVAL (continued)

SCR Heat

Sink Assemblies

Return to Section TOC

Return to Section TOC

Return to Master TOC

Return to Master TOC

TEST PROCEDURE

1.Remove main power supply to machine.

2.Remove case sides and top.

3.Locate SCR heat sink assemblies.

4.Remove all gate, snubber and cable leads from the SCR heat sink assembly that is to be serviced.

5.Remove the four 1/4”-20 hex nuts and associated plain and lock washers from the four 1/4”-20x1.75” hex head cap screws. Remove the heat sink assem- bly trying not to disturb the insulating washers and bushings. See figure above.

6.Reinstall the heat sink assembly in the same manner being certain that the insulating washers and bushings are installed correctly. See figure above.

7.Test with an ohmmeter to make certain that the heat sink assembly is electrical- ly isolated from chassis ground by at least 500,000 ohms of resistance.

8.Reconnect the gate leads.

9.Reconnect the snubber and cable leads using a thin coating of Dow 340 heat sink compound on the connection sur- faces. Be sure that the connection sur- faces are clean and free from any dirt or paint.

SQUARE WAVE TIG 255