Lincoln Na5 Service Manual

NOTESC-6C-6
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TABLE OF CONTENTS
- MAINTENANCE SECTION - 
NA-5
Maintenance  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
 . . . . . . . . Section D
Control Box  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
 . . . . . . D-2General  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
 . . . . . . D-2
Circuit Protection  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D-2
Ground Fault Fuse Protection  . . . . . . . . . . . ....

D-2MAINTENANCED-2
NA-5
CONTROL BOX
GENERAL
Inspect the control box every 3 months. If
needed, blow dirt out using 
lowpressure air.
No further maintenance should be required.
CIRCUIT PROTECTION
The circuit breaker mounted on the left side
of the control box protects the control circuit
from short circuit conditions and from severe
wire feed overloads. If it is open, determine
and correct the cause for the overload. To
reset the circuit breaker, push in the red
button shown in Figure D.1.
FIGURE D.1 –...

MAINTENANCED-3D-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 
Automatic Shutdownin
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...

MAINTENANCED-4D-4
NA-5
WIRE DRIVE MOTOR
Periodically inspect the wire drive motor
brushes, Figure D.4. Replace the brushes
as needed.
CHANGING WIRE FEED GEAR
RATIOS
Four wire size conversion kits are available
to modify the wire feeder for different size or
type electrodes.  The kits include drive rolls
and guide tubes for the wire specified, as
shown in Table D.1.TABLE D.1 - CONVERSION  KITS
Wire Type in. (mm) Conversion Kit
3/32-7/32 (2.38-5.56) T13724-A Solid or Cored
1/16-3/32 (1.59-2.38) T13724-B...

MAINTENANCED-5D-5
NA-5
3. Pull the gear from the shaft using thescrews as a pulling device.
4. Be certain woodruff key (8) is properly located on the shaft. Screw the
adapter plate and motor assembly
mounting screws into the new fiber
input helical gear from the stenciled
side and place the gear on the shaft.
Replace plain washer (9), tighten the
hex nut (1), and remove the adapter
plate and motor assembly mounting
screws from the gear.
5. After noting the relation of the adapter plate with the motor...

MAINTENANCED-6D-6
NA-5
OPTIONAL FEATURES
CONTACT ASSEMBLIES
A dirty or rusty electrode and excessively
high currents cause rapid wear of the
contact tips. The nozzle contact tip must be
replaced when it no longer provides accurate
wire location or good electrical contact. See
Sec. T2.2.6, Sec. T2.2.7, or Sec. T2.5.3 of
the IM305 manual for specific instructions to
replace contact tips and to perform
maintenance on other various contact
assemblies.
WIRE REEL MOUNTING FOR
50 OR 60 LB (22.7 OR
27.2 KG)...

E-1THEORY OF OPERATIONE-1
NA-5
TABLE OF CONTENTS 
-THEORY OF OPERATION SECTION-
Theory of Operation ........................................................................\
..........................................Section E General Description........................................................................\
..................................................E-2
Input Power Circuits ........................................................................\...

E-2THEORY OF OPERATIONE-2
INPUT POWER CIRCUITS
The NA-5 control unit is supplied with
115VAC power usually from the welding
power source.  The 115VAC power is
connected to the control box circuitry
through the control cable receptacle,
the input power switch and a 5 amp cir-
cuit breaker. 
The 115VAC is applied through a 2 ohm
resistor to the power board where is
rectified and controlled to supply arma-
ture and field voltage to the wire drivemotor.  The voltage board receives
115VAC and transforms and...

E-3THEORY OF OPERATIONE-3
POWER AND VOLTAGE
BOARDS
The AC voltages that are received by
the power board are rectified and regu-
lated.  These DC voltages are supplied
to the motor, voltage board and control
board.  The two SCR-controlled
115VDC supplies power the motor
armature and field circuits.  
The actual arc voltage is sensed at leads
#67(electrode) and #21(work) which are
coupled to the voltage board.  The pre-
set voltage requirements are also sent to
the voltage board.  This information is...