Lincoln Electric LF-72/74 Service Manual page 100

F-16
TROUBLESHOOTING AND REPAIR
CONTROL PC BOARD REMOVAL AND REPLACEMENT PROCEDURE
REMOVAL PROCEDURE
1. Remove the input power ( 42VAC )
from the LN72/LN74 unit.
2. Using the 5/16 nut driver remove the 5
screws holding the cover.
3. Locate the control board (see figure F.6)
and remove the harness plugs on the
control board. Observe static electricity
precautions.
4. Remove the 4 nuts holding the board
using the 3/8 inch nut driver, and remove
the board.
(Continued)
Figure F.6 - PC Board Location
REPLACEMENT PROCEDURE
1. Remove the new control board from the
2. Reassemble the 4 nuts and tighten hand
3. Reassemble the harness plugs.
4. Reassemble the case.
LF-72/74
CONTROL BOARD
static bag and place it on the 4 studs.
tight.
F-16