Lincoln Electric SVM118-A service manual Figure F.31 SCR Clamp Assembly Details 5/8 Wide Spring

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F-83 TROUBLESHOOTING & REPAIR F-83

SCR REMOVAL AND AND REPLACEMENT (continued)

FIGURE F.31 – SCR CLAMP ASSEMBLY DETAILS – 5/8” WIDE SPRING

Cap Screw

Steel Pressure Pad

Leaf Spring

Plastic Housing

Heat Sink

SCR

Heat Sink

Plain Washer

Clamp Nut

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Clamping procedure for 1/4-20 cap screws. Note: This procedure can only be used with 1/4-20 cap screws. Do not use cap screws with any other type thread, or the new SCR will be damaged. Do not overtighten the cap screws. The leaf spring will apply the required clamping force to the SCR.

a.Do not turn the nuts. While holding the nuts stationary, turn the cap screws only with the following procedure.

b.Tighten first cap screw 1/4 turn.

c.Tighten second cap screw 1/2 turn.

d.Tighten the first cap screw 1/2 turn.

e.Tighten the second cap screw 1/4 turn.

f.Tighten the first cap screw 1/8 turn.

g.Tighten the second cap screw 1/8 turn. Stop. The assembly now has the proper clamping force.

8)Perform the Active SCR Test.

10.Install the output rectifier heat sink assem- bly back into the machine. See Output Rectifier Removal and Replacement in this section of the manual.

SQUARE WAVE TIG 355