Lincoln Electric PRECISION TIG 185 SVM169-A Service Manual page 84

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REMOVAL AND REPLACEMENT PROCEDURE (Continued) REMOVAL AND REPLACEMENT PROCEDURE (Continued)
REMOVAL PROCEDURE
1. Remove the input power to the TIG
185 machine.
2. Using the 3/8" nutdriver remove the
case wrap-around cover.
3. Using the 3/32" Allen type wrench
remove the output control knob.
4. Using the Phillips head screwdriver
remove the screw from the polarity
switch handle.
5. With the 2 slot head screwdrivers
carefully pry the polarity switch han-
dle from the shaft.
6. Remove the five plastic snap rivets
holding the name plate to the case
front. These can be removed by gen-
tly prying at the rivet between the
name plate and the case front.
7. Remove the name plate.
8. With the 1/2" wrench remove the
"positive" flex lead from the polarity
switch. See wiring diagram. Label
lead and connection point for
reassembly.
9. With the 1/2" wrench remove the
"AC" flex lead from the polarity
switch. This lead connects to the AC
plate on the SCR bridge. See wiring
diagram. Label lead and connection
point for reassembly.
10. Using the 1/2" wrench remove the
flex lead from the rear gang of the
polarity switch. This lead connects
to the D1 diode on the SCR bridge.
See wiring diagram. Label lead and
connection point for reassembly.
11. Using the 1/2" wrench remove the
flat copper lead from the polarity
switch. This lead connects to the
high frequency transformer coil and
the by-pass board. See wiring
diagram. Label lead and connec-
TROUBLESHOOTING & REPAIR
POLARITY SWITCH POLARITY SWITCH
PRECISION TIG 185
tion point for reassembly.
12. Using the 1/2" wrench remove the
other flat copper lead from the
polarity switch. This lead connects
to the lower terminal on the by-pass
board and the "work" lead.
wiring diagram. Label lead and
connection point for reassembly.
13. Using the 1/2" wrench remove the
choke lead from the polarity switch.
See wiring diagram. Label lead and
connection point for reassembly.
14. With the 1/2" wrench remove the X1
secondary lead from the polarity
switch. See wiring diagram. Label
lead and connection point for
reassembly.
15. With the 7/16" wrench remove the
two nuts and washers that hold the
polarity switch to the front panel.
16. Carefully rotate the polarity switch
assembly to gain access to the
micro-switch.
17. Carefully unsolder the two leads
(#311 and #312) from the micro-
switch located on the polarity switch
assembly. See wiring diagram.
Label leads and connection points
for reassembly.
18. Carefully remove the polarity switch
assembly from the machine.
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See