Lincoln Electric NA-3 Service Manual page 94

F-29
AC CURRENT TRANSFORMER AND SENSOR PC
BOARD REMOVAL AND REPLACEMENT (NA-4 ONLY)
REMOVAL PROCEDURE
1. Remove the input power to the NA-4
control box.
2. Using the 5/16 in. nutdriver, remove
the four sheet metal screws holding
the current sensor box cover to the
control box sheet metal.
3. Using the slot head screwdriver,
remove leads #539 and #528 from the
terminal strip inside the control box.
4. Using the 7/16 in. wrench, remove the
three nuts, washers, insulating
spacers, and bolts that hold the
current transformer in place.
5. Carefully slide the glastic spacer and
current transformer off of the copper
conductor bar.
6. To remove the current sensor PC
board, remove the screw, 3/8 in. nut,
lockwasher, and insulators mounting
the PC board coil to the metal bracket
on the other glastic spacer.
7. Carefully remove the PC board; be
careful when pulling leads #539 and
#528 free from the grommet in the
back of the control box.
TROUBLESHOOTING AND REPAIR
(continued)
NA-3 AND NA-4
INSTALLATION PROCEDURE
1. Feed leads 539 and 528 through the
grommet in the back of the control
box.
2. Install the current sensor PC board
and PC board coil onto the glastic
spacer with the insulators, lock
washer, 3/8 in. nut, and screw.
3. Slide the current transformer and the
other glastic spacer onto the copper
conductor bar.
4. Secure the current transformer and
glastic spacers with three bolts,
insulating spacers, washers and nuts
using the 7/16 in. wrench.
5. Connect leads 539 and 528 to the
terminal strip using the slot head
screwdriver.
6. Install the shunt box cover onto the
control box with four sheet metal
screws using the 5/16 in. nutdriver.
F-29