Lincoln Electric SQUARE WAVE TIG 355 Service Manual page 90

F-38
FEED-THRU PC BOARD TEST (continued)
PROCEDURE
1. Remove input power to the machine.
2. With the 5/16" nutdriver, remove the machine
top and sides.
3. Perform the Power
Discharge Procedure.
4. Remove plugs J15, J16, J17, and J18 from the
feed-thru PC board. See Figure F.8 for location.
5. Remove the 4 phillips head screws mounting
the feed-thru PC board to the floor of the control
box. See Figure F.8.
6. Carefully remove the feed-thru PC board.
7. Test for the resistances between the check
points listed on the Feed-Thru PC Board
Resistance Test Points Chart. See Figures F.9
and F.10.
• If any of the resistances are out of specifica-
tion, replace the feed-thru PC board.
TROUBLESHOOTING AND REPAIR
FIGURE F.8 – FEED-THRU PC BOARD LOCATION
Factor Capacitor
SQUARE WAVE TIG 355
8. After the tests are completed and the problem
repaired, install and connect the feed-thru PC
board:
• Carefully mount the board to the floor of the
control box using the 4 phillips head screws.
• Connect plugs J15, J16, J17, and J18 to the
board.
9. With the 5/16" nutdriver, install the machine
sides and top.
F-38