Lincoln Electric IDEALARC DC-1000 Service Manual page 88

F-54
SCR OUTPUT BRIDGE REPLACEMENT (continued)
FIGURE F.22 – PREPARATION FOR SCR OUTPUT BRIDGE REMOVAL
PROCEDURE
1. Remove input power to machine.
2. Using a 5/16 (8mm) nut driver or flat head
screw driver, remove 20 screws (ten per side) to
remove case sides and 2 screws to remove top.
3. Using a 5/16 (8mm) nut driver or flat head
screw driver, remove 6 screws, then lower the
front control panel.
4. Remove the J4 gate lead Molex plug from firing
board, and feed the plug down through the hole
in bottom of the PC board compartment.
5. Using a 9/16" socket and open-end wrench,
remove the two bolts and nuts holding the shunt
assembly to the two positive buss leads con-
nected to the SCR bridge. See Figure F.22.
6. Using a 5/16" socket, remove the screw and
small reed switch lead (#210) from the left, top
rear SCR heat sink.
TROUBLESHOOTING AND REPAIR
IDEALARC
NOTE: It may be necessary to move or remove
the output choke to gain access to the bot-
tom anode leads. For access to the bottom
middle screw, nut, and associated wash-
ers, a long handled flat ratchet is recom-
mended.
7. Identify and label the six transformer secondary
(heavy aluminum) leads that connect to the
anodes of the SCR heat sink assemblies. Using
a 1/2" socket and open-end wrench, remove the
secondary leads see Figure F.22.
8. Support the SCR bridge assembly with a lift
hook or rope.
9. Using a 3/8" socket wrench, remove the two
screws (one on each side) holding the SCR
assembly rails to the front panel assembly.
® DC-1000
F-54