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TROUBLESHOOTING & REPAIR | ||
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SCR OUTPUT BRIDGE REPLACEMENT
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SCR HEAT SINK
INSTALLATION
NOTE: Upon reassembly, apply a thin layer of Lincoln E1868 (Dow Corning #340) heat sink compound to all bolted electrical connections on the aluminum heat sinks, including positive buss bar.
1.Slide a new SCR assembly onto the mounting studs.
2.Carefully attach the positive buss bar onto the heat sink which had been removed. If it had been nec- essary to remove the buss bar, replace it at this time.
3.Align snubber assembly in position on SCR output bridge assembly.
4.Using a 9/16” wrench, secure the SCR output bridge and snubber assemblies with two nuts, flat wash- ers, and lock washers.
5.Using a 5/16 (8mm) nut driver or flat head screw driver, attach snubber assembly ground wire with screws previously removed.
SCR OUTPUT BRIDGE
INSTALLATION
NOTE: Upon reassembly, apply a thin layer of Lincoln E1868 (Dow Corning #340) heat sink compound to all bolted electrical connections on the aluminum heat sinks.
1.Support the SCR bridge assembly with a lift hook or rope.
2.Clear all leads and carefully posi- tion the SCR bridge assembly in place.
3.Place insulators between SCR bridge assembly and the output rectifier mounting bracket. See Figure F.23. Check for electrical isolation with an analog ohmmeter. Minimum acceptable resistance to ground is 500,000 ohms.
4.With the 5/16” socket wrench, attach bottom six screws securing the front panel assembly to the base. Carefully push the front panel rearward into position.
5.Attach resistor R2 to the unit using a 7/16” wrench Secure leads #217 and #222 to resistor R2.
6.Using a 1/2” socket wrench, attach the four screws (2 on each side) holding the transformer side panels and SCR assembly rails to the main transformer.
