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F-53

F-53

TROUBLESHOOTING & REPAIR

SCR RECTIFIER BRIDGE REMOVAL AND

REPLACEMENT PROCEDURE (continued)

FIGURE F.20 – SCR RECTIFIER BRIDGE ASSEMBLY DETAILS

MAIN TRANSFORMER

SECONDARY LEADS

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SCR

RECTIFIER

BRIDGE

LEG

ASSEMBLY

MOUNTING

BRACKETS

5.Using the 1/2” socket wrench, remove the six transformer secondary leads from the heat sink assembly. The small “A” leads do not have to be removed. Note lead place- ment for reassembly. See the Wiring Diagram and Figure F.20.

6.With the 9/16” wrench, remove the shunt from the left side of the heat sink assembly.

7.With the 3/8” wrench, remove the four mounting bolts that hold the heat sink assembly to the horizontal mounting brack- ets. Be sure to remove the insulators and take note of placement for reassembly.

8.While supporting the heat sink assembly, remove the left side horizontal mounting bracket from the left side leg assembly. See Figure F.20.

9.Carefully slide the rectifier heat sink assem- bly from the machine. Clear all leads.

REASSEMBLY

1.Upon reassembly, apply a thin coating of Dow Corning 340 Heat Sink Compound to all bolted connections.

2.With the left side horizontal mounting brack- et removed, slide the heat sink assembly into the machine.

3.Support the heat sink assembly and install the left side mounting bracket. Then mount the heat sink assembly to the bracket with four bolts. Note insulator placement.

4.Attach the shunt to the left side of the heat sink assembly.

5.Install the six transformer secondary leads to the heat sink assembly. See the Wiring Diagram.

6.Connect lead #222 to the high inductance output terminal.

7.Install plugs J9 and J20 onto the thermal fan/snubber board.

8.Replace any cable ties cut at disassembly.

9.Install the case top and sides.

IDEALARC DC-655

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Lincoln Electric DC-655 service manual Reassembly, SCR Rectifier Bridge LEG Assembly Mounting Brackets