Lincoln Electric R3R-500, R3R-300 service manual After Replacing the SCRs

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F-51 F-51

TROUBLESHOOTING & REPAIR

SCR REMOVAL AND REPLACEMENT (continued)

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CLAMPING PROCEDURE

FOR 1/4-28 CAP SCREWS

NOTE: This procedure can only be used with 1/4-28 cap screws.

Do not use cap screws with any other type thread or new SCR will be damaged.

Do not over tighten cap screws. The leaf spring will apply the required clamping force to the SCR.

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

2.Tighten first cap screw 1/4 turn.

3.Tighten second cap screw 1/2 turn.

4.Tighten first cap screw 1/2 turn.

5.Tighten second cap screw 1/2 turn.

6.Tighten first cap screw 1/2 turn.

7.Tighten second cap screw 1/4 turn. STOP.

8.Assembly now has the proper clamping force.

9.Perform the Active SCR Test.

AFTER REPLACING THE SCRs

Follow the steps in the SCR/Diode Rectifier

Removal and Replacement procedure to

reassemble the machine.

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 new SCR will be damaged.

Do not over tighten cap screws. The leaf spring will apply the required clamping force to the SCR.

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

2.Tighten first cap screw 1/4 turn.

3.Tighten second cap screw 1/2 turn.

4.Tighten first cap screw 1/2 turn.

5.Tighten second cap screw 1/4 turn.

6.Tighten first cap screw 1/8 turn.

7.Tighten second cap screw 1/8 turn. STOP.

8.Assembly now has the proper clamping force.

9.Perform the Active SCR Test.

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IDEALARC R3R