Lincoln Electric IDEALARC DC-1000 Service Manual page 89

F-55
SCR OUTPUT BRIDGE REPLACEMENT (continued)
10. Cut any necessary cable ties to allow for the
SCR bridge assembly removal.
11. Using a 1/2" socket wrench, remove the four
screws (2 on each side) holding the trans-
former side panels and SCR assembly rails to
the main transformer. See Figure F.23.
12. Remove leads #217 and #222 from resistor R2
located on the lift bail assembly. Remove resis-
tor R2 using a 7/16" wrench.
13. With the 5/16" socket wrench, remove the bot-
tom six screws holding the front panel assem-
bly to the base. Carefully pull the front panel
forward to allow room to remove the SCR
bridge assembly.
14. Clear all leads and carefully remove the SCR
bridge assembly.
NOTE: Upon reassembly, apply a thin layer of
Lincoln E1868 (Dow Corning 340) heat
sink compound to all bolted electrical con-
nections on the aluminum heat sinks.
TROUBLESHOOTING AND REPAIR
FIGURE F.23 – SCR OUTPUT BRIDGE REMOVAL
IDEALARC
WARNING
UPON REASSEMBLY, THE
ASSEMBLY MUST BE ELECTRICALLY ISOLAT-
ED FROM GROUND.
_________________________________
15. Place insulators between SCR bridge assem-
bly and the output rectifier mounting bracket
(see Figure F.23). Check for electrical isolation
with an analog ohmmeter.
WARNING
MINIMUM ACCEPTABLE
GROUND IS 500,000 OHMS.
_________________________________
® DC-1000
F-55
SCR BRIDGE
RESISTANCE TO