Lincoln Electric PRECISION TIG 185 SVM169-A Service Manual page 81

F-43
REMOVAL AND REPLACEMENT PROCEDURE (Continued)
16. With the 3/8" wrench remove the
four mounting screws holding the
SCR bridge assembly to the main
transformer frame. Note insulator
placement.
17. Carefully remove the SCR bridge
assembly from the TIG 185 cutting
any necessary cable ties.
REPLACEMENT PROCEDURE
1. Carefully place the new SCR bridge
assembly in position in the TIG 185.
2. Using the 3/8" wrench install the four
mounting screws taking special care
that the insulators are in the correct
positions.
USE DOW CORNING 340 HEAT SINK
COMPOUND ON ALL ALUMINUM
CONNECTIONS
3. Assemble the positive lead to the
right side positive heat sink.
4. Assemble the lead from the polarity
switch to the right side AC heat sink.
Note: Also connect lead #216
5. Assemble the shunt to the SCR
bridge left side negative heat sink.
6. Assemble the X2 secondary trans-
former lead to the left side AC SCR
heat sink. Note: Also connect lead
#217
7. Assemble the diode pigtail lead to
the polarity switch lead. See Figure
F.10.
and secure with cable ties. Position
with harness and secure with cable
ties.
8. Replace any previously removed
cable ties.
TROUBLESHOOTING & REPAIR
SCR BRIDGE ASSEMBLY
Be sure to replace sleeving
PRECISION TIG 185
9. Position the internal divider panel
and secure with the screws previous-
ly removed.
10. Install the J2 plug into the control
board and position the harness in
the internal divider panel.
11. Position and install the case back
and secure with the screws previ-
ously removed.
12. Install the gas hose onto the sole-
noid valve.
13. Tighten the input cable strain relief.
14. Assemble the case wrap-around
cover.
F-43