Welding head, Ground fault fuse protection, Wire drive gear box – Lincoln Electric NA-5S User Manual
Page 44: Maintenance
MAINTENANCE
D-3
D-3
NA-5
The 1/8 amp fast-blow fuse, shown in Figure
D.3, on a voltage PC board built since 1983,
protects the NA-5 circuitry from damage
which may result from a ground or case
faulted control lead. If the fuse blows, the
NA-5 voltage sensing lead circuit will be
opened (Refer to
Section B, Operating Procedures) and the
Troubleshooting Guide.
FIGURE D.3 – VOLTAGE BOARD FUSE
LOCATION.
GROUND FAULT FUSE
PROTECTION
A 1/8 amp fast-blow fuse, shown in Figure
D.3, is located on the voltage PC board.
This fuse will protect the NA-5 circuitry from
damage resulting from a ground or case
faulted control lead when the arc voltage
potential exists between ground and the
NA-5 circuit common (#510). Such a
condition typically exists when the NA-5
polarity connections are set for electrode
negative.
WELDING HEAD
WIRE DRIVE GEAR BOX
Once a year, recoat all gear teeth with a
non-fluid molydisulfide type grease such as
Non-Fluid Oil Corporation’s A-29 Special/MS
Lubricant. For access to the gears in the first
chamber, remove the adapter plate and
motor assembly as shown in Figure D.4.
FIGURE D.4 – WIRE DRIVE MOTOR
GEAR BOX.
To lubricate the gears in the second
chamber, remove one of the pipe plugs and
feed grease until it comes in contact with the
bevel gear teeth. Then, rotate the output
shaft by hand until all teeth are lubricated.
1/8 AMP
FAST-BLOW
FUSE
NA-5
VOLTAGE
HEX HEAD
SCREW
ADAPTER
PLATE AND
MOTOR
ASSEMBLY
FIRST
CHAMBER
WIRE DRIVE
GEARBOX
SECOND
CHAMBER
SLOT HEAD
SCREW
PIPE
PLUG
DRIVE MOTOR
BRUSH ACCESS