Lincoln Na5 Service Manual

							NOTESC-6C-6
NA-5  Return to Section TOCReturn to Section TOCReturn to Section TOC Return to Section TOCReturn to Master TOCReturn to Master TOCReturn to Master TOC Return to Master TOC 
						

							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-3
Welding Head  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
 . . . . . D-3 Wire Drive Gear Box  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D-3
Wire Drive Motor   . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D-4
Changing Wire Feed Gear Ratios . . . . . . . . . . . . . . . . . . . . .\
 . . . D-4
Wire Drive Mechanism  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D-5
Wire Straighteners  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D-5
Optional Features  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
 . . D-6 Contact Assemblies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D-6
Wire Reel Mounting for 50 or 60 lb (22.7 or 27.2 kg) Coils  . . . . . D-6
Travel Carriage  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
 . D-6
Vertical Lift Adjuster  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D-6
Horizontal Adjuster  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D-6
High Frequency Generator  . . . . . . . . . . . . . . . . . . . . . . . . . . . . D-6
Spreadarc . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
 . . . . . D-6
Section DSection D
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							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 – CIRCUIT BREAKER RESET BUTTON. If a complete or partial short occurs in the
field circuit, or if there is a defect on the PC
board, a 1/2 amp slow-blow type fuse will
blow.  This field circuit fuse is mounted on the
power PC board, shown in Figure D.2, inside
the control box.  Before replacing the fuse,
check the motor field for a short condition.
Normal resistance is approximately 700
ohms.
With NA-5 controls above Code 8300, the
field circuit fuse may blow due to frequent
motor field reversals from application
problems affecting the “cold” starting circuit,
such as the power source output being too
low to establish an arc or the welding
procedure causing frequent electrode-to-
puddle shorting. (Refer to 
Automatic
Shutdown 
in Section B, Operating
Instructions.)
FIGURE D.2 – POWER PC BOARD FUSE LOCATIONS.
The power supply for the electronic circuitry
is protected by a 1/2 amp slow-blow type fuse
shown in Figure D.2.  It is located on the
power PC board inside the control box.
CIRCUIT
BREAKER
RESET  BUTTON
FIELD
1/2 AMP
SLOW-BLOW
 FUSE
POWER
1/2 AMP
SLOW-BLOW
 FUSE
NA-5 POWER
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							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 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
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							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 Solid or Cored
0.035-0.052 (0.89-1.32) T13724-C Solid
0.045-0.052 (1.14-1.32) T13724-D Cored
Refer to Table D.2. Four gear ratios are
available: 21:1, 57:1, 95:1, and 142:1.  To
change the gear ratio, replace the motor
pinion and the first reduction gear per the
following instructions (Refer to Figures D.4,
D.5 and D.6).
NOTE
: Any item numbers in parentheses
on Figure D.5 refer to item numbers in the
task description breakdown. FIGURE D.5 – CHANGING THE WIRE
FEED GEAR RATIO
1. Remove the four screws that mount the adapter plate and motor assembly
to the gear box. Remove the adapter
plate and motor assembly from the
gear box.
2. Take the two long screws removed in step 1 and screw one into each of the
tapped holes located on the face of
fiber input helical gear (12). Insert the
screws through the full thickness of
the gear, and using a screwdriver
wedged between the screws to
prevent rotation, remove hex nut (11)
that holds the gear to the shaft.
Remove plain washer (9).
TABLE  D.2 – WIRE  FEED  GEAR RATIOS. Feed Speed Max Wire Size
Gear Range in. (mm)
Ratio in/min (m/min)
Cored Wire Solid Wire
21:1 100-2070 (2.54-52.58) 0.052 (1.3) 0.052 (1.3)
57:1 40-778 (1.02-19.76) 3/32 (3.0) 1/16 (1.6)
95:1 22-456 (0.56-11.58) 5/32 (4.0) 1/8 (3.2)
142:1 15-300 (0.38-7.62) 5/32 (4.0) 7/32 (5.6)
HEX NUT (11)
PLAIN WASHER (9)
WOODRUFF
KEY (8)
WIRE
FEED
GEARBOX INPUT
HELICAL
GEAR (12)
SLOT  HEAD 

SCREWS
(MOUNTING 
 SCREWS)
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							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 leads, remove
the adapter plate from the wire drive
motor. See Figure D.6. Support the
pinion properly and, with the proper
size punch, drive the roll pin that
holds the pinion out of the shaft. Pull
the pinion off. Install the new pinion
and replace the roll pin. Replace the
adapter plate in its original location.
6. Cover the teeth of the motor pinion and the input gear with a non-fluid
molydisulfide type grease such as
Non-Fluid Oil Corporation’s A-29
Special/MS Lubricant. This grease
can be scooped from the cavity of the
gear case.
7. Reassemble the motor on the gear box; make sure the gears mesh
properly and the adapter plate
locating bead is in its cavity. Replace
and tighten the four screws  removed
in step 1.
8. Jumper on wire speed meter PC board must be properly positioned for
the gear ratio and drive rolls being
used (See the wiring diagram for the
wire speed meter PC board.)
WIRE DRIVE MECHANISM
Drive mechanisms for three wire size ranges
are available: 0.035 through 0.052 in.
(0.9 through 1.3 mm), 1/16 through 3/32 in.
1.6 through 2.4 mm), and 3/32 through
7/32 in. (2.4 through 5.6 mm). If changing to
wire sizes outside this range, change the
drive rolls and the incoming and outgoing
guide tubes. Also change the gear ratio as
necessary. The electrode is driven by gripping
between the grooved drive rolls and
spring-loaded idle roll. Replace the drive
rolls when they become worn. The drive rolls
for 1/16 in. (1.6 mm) and larger diameter
electrodes have two sets of teeth so they
can be reversed once before they must be
replaced.
WIRE STRAIGHTENERS
Solid Electrode
Periodically inspect the slide bushing at the
top of the straightener and the ingoing wire
guide at the bottom of the straightener for
signs of wire milling. If necessary, rotate the
guide to present an unworn surface. To
reverse the slide bushing for a fresh wear
surface, remove the cross adjustment screw
and turn the bushing over.
Flux-Cored Electrode
Severe wear at the “V” groove in the curved
arm of the straightener can result in wire
wander at the arc. Periodically check the
groove and replace the arm when badly
worn. Also replace the ingoing guide at the
top of the straightener if it shows signs of
wire milling.
WIRE
DRIVE
MOTOR
SHAFT
ADAPTOR
 PLATE
PINION
ROLL PIN MOUNTING
SCREW (X3)
FIGURE D.6 – DRIVE MOTOR PINION GEAR REMOVAL.
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							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) COILS
Periodically coat the reel shaft with a thin
layer of grease. No maintenance of the two-
position adjustable brake is needed except
to replace the shoe assembly if it wears
through.
TRAVEL CARRIAGE 
Periodically: 1. Disengage the release handle and see that the carriage moves freely
along the beam.
2. Add a few drops of machine oil to each of the head lift bearings.  This
can be done through the front
opening in the carriage.
3. Add a few drops of oil to the clutch handle bearings.
4. Add a few drops of oil into each of the cups at the travel mounting pivot
point.
(No change of lubrication is required
for cold temperature operation.) 
Once a year: 1. Check the motor brushes.  If 0.25 in. (6.35 mm) or shorter, replace with
new brushes. 2. Check the carriage drive gear teeth.
If the teeth are badly worn, replace
the drive gear.
3. After 5,000 hours of operation, the motor and the first reduction gear
should be removed from the gear box,
and all the gear teeth should be
recoated with a good grade of
graphite grease.
VERTICAL LIFT ADJUSTER 
Every month, add a few drops of SAE-140
oil or equivalent to the oil cup on the back
of the vertical lift housing. Every year,
replace the grease in the top section gear
cavity with a medium grease. If the unit is
disassembled for cleaning, apply a layer of
medium grease to the screw threads of the
head lift tube and head lift screw.  Apply a
thin layer of grease to the outside diameter
of the head lift tube and the inside diameter
of the long hole in the head lift body. Slide
the head lift tube into the head lift body and
screw in the head lift screw. Fill the upper
section gear cavity one-half full of grease.
Be sure the needle bearings are packed in
grease.
HORIZONTAL ADJUSTER
Twice a year, apply a thin coat of grease to
all sliding surfaces. Every year, replace the
grease in the gear cavity with a medium
grease.
HIGH FREQUENCY GENERATOR 
Inspect the spark gaps monthly and maintain
the setting specified on the spark gap cover
plate.
SPREADARC 
Refer to the maintenance information
provided in IM305 Sec. T2.5.6.
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							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-2
Power and Voltage Boards........................................................................\
.......................................E-3
Control, Logic and Procedure Boards ........................................................................\
......................E-4
Optional start, Crater Fill and Weld Timer Boards........................................................................\
....E-5
SCR Operation ........................................................................\
.........................................................E-6
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							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 rectifies it
to 24VDC for the work touch sensing
circuit.  The T1 and T2 transformer pri-
maries are also supplied with 115VAC
via the F1 (1/2amp) fuse on the power
board.  The T1 and T2 secondary wind-
ings offer a variety of isolated AC sup-
ply voltages to the power, logic and
meter boards.
FIGURE E.1 Input Circuits
NA-5
F1
A
R
M
A
T
U
R
E
F
I
E
L
D
V
O
L
T
A
G
E V
O
L
T
A
G
E
T1
T2
OPTIONAL
START
BOARD
OPTIONAL CRATER BOARD
OPTIONAL WELD
TIMER
BURNBACK TIMER
VOLTAGEBOARD
METER
BOARD SPEEDVOLT
METER
BOARD
DIGITALMETER DIGITAL
METER
MOTOR
LOGIC
BOARD
CONTROL BOARD
P
O
W E
R
B
O
A
R
D
P
R
O
C
E
D
U
R
E B
O
A
R D
TACH
INCH
DOWN
SWITCHSTOP
SWITCHSTART
SWITCH
WELD 
CURRENT
REED SWITCH
CR
1
CR
2
CR 3
FLUX
RECEPTACLE
TRAVEL
RECEPTACLE
CONTACTOR  CLOSURE (#2 AND  #4)
REMOTE VOLTAGE CONTROL (A, B, C)
WORK SENSING (#21)TACH FEEDBACK (MOTOR RPM)
DC SUPPLY VOLTAGE
10VDC  REFERENCEVOLTAGE
DC  VOLTAGE S
I
G
N
A
LINPUT
POWER
SWITCH CIRCUIT
BREAKER R1(2 OHMS)
MOTOR
G
A
T
E
S
I
G
N
A
L
S
CONTROL
CABLE
RECEPTACLE
TACH FEEDBACK (MOTOR RPM)
115VAC
36VAC (18+18VAC)
22VAC
1
V
A
C 0 D
C
S
U
P
P
L
Y
V
O
L
T
A
G
E
SIGNAL
A
R
C
V
O
L
T
A
G
E S
H
U
T
D
O
W
N A
N
D
INCH
UP
SWITCH STRIKE/WELD PROCEDURE
ENABLE
FIELD
ARMATURE F
E
E
D
E
N
A
B
L
EDIRECTION
ARC VOLTS (SET & ACTUAL)
WIRE FEED SPEED (SET & ACTUAL)
E L E
C
T
ROD E SENSING
(#67)
1
15
VAC
WELDVOLTS SPEED
VOLTSSPEED
STRIKE
115VAC
#31
#32
1/2 AMP F501
SET SPEED
SET VOLTAGE
STARTTIMER
CRATER TIMERF2
NOTE:Unshaded areas of block logic diagrams are the subject of discussion.
GENERAL DESCRIPTION
The NA-5 is a fully automatic wire feed
control unit.  It is designed for multiple
process CV operation and can be used
with a variety of wire feeder heads, con-
tact nozzles and welding processes.
The NA-5 control unit enables the oper-
ator to preset wire feed speed and arcvoltage on digital meters.  These preset
conditions are internally monitored and
remain constant until changed by the
operator.  
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							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
compared and  processed on the voltage
board and the resultant correction signal
is sent to the Lincoln CV power source
via the remote voltage leads (A,B,C).
The preset and actual arc voltage infor-
mation is also sent to the voltage meter
board where it is processed and dis-
played on the digital meter.  
The voltage board also generates a low
DC voltage that is applied to the elec-
trode during the inch down mode.
When the electrode makes contact with
the work piece, this low voltage is
loaded down, signaling the control cir-
cuitry to stop the wire feed motor.  This
feature allows the operator to utilize the
work touch sensing feature.
If for any reason the actual welding arc
voltage does not match the set weld
voltage 
(+/- 0.5Volts)  the NA-5 will shutdown.
This feature insures that the actual
welding voltage is the same as the pre-
set voltage during the welding cycle.
This circuitry is incorporated on the volt-
age board.
FIGURE E.2 Power and Voltage Boards
NA-5
F1
A
R
M
A
T
U
R
EF
I
E
L
D
V
O
L
T
A
G
E V
O
L
T
A
G
E
T1
T2
OPTIONAL
START
BOARD
OPTIONAL CRATER BOARD
OPTIONAL WELD
TIMER
BURNBACK TIMER
VOLTAGEBOARD
METER
BOARD SPEEDVOLT
METER
BOARD
DIGITALMETER DIGITAL
METER
MOTOR
LOGIC
BOARD
CONTROL BOARD
P
O
W E
R
B
O
A
R
D
P
R
O
C
E
D
U
R
E B
O
A
R D
TACH
INCH
DOWN
SWITCHSTOP
SWITCHSTART
SWITCH
WELD 
CURRENT
REED SWITCH
CR
1
CR
2
CR 3
FLUX
RECEPTACLE
TRAVEL
RECEPTACLE
CONTACTOR  CLOSURE (#2 AND  #4)
REMOTE VOLTAGE CONTROL (A, B, C)
WORK SENSING (#21)TACH FEEDBACK (MOTOR RPM)
DC SUPPLY VOLTAGE
10VDC  REFERENCEVOLTAGE
DC  VOLTAGE S
I
G
N
A
LINPUT
POWER
SWITCH CIRCUIT
BREAKER R1(2 OHMS)
MOTOR
G
A
T
E
S
I
G
N
A
L
S
CONTROL
CABLE
RECEPTACLE
TACH FEEDBACK (MOTOR RPM)
115VAC
36VAC (18+18VAC)
22VAC
1
V
A
C 0 D
C
S
U
P
P
L
Y
V
O
L
T
A
G
E
SIGNAL
A
R
C
V
O
L
T
A
G
E S
H
U
T
D
O
W
N A
N
D
INCH
UP
SWITCH STRIKE/WELD PROCEDURE
ENABLE
FIELD
ARMATURE F
E
E
D
E
N
A
B
L
EDIRECTION
ARC VOLTS (SET & ACTUAL)
WIRE FEED SPEED (SET & ACTUAL)
E L E
C
T
ROD E SENSING
(#67)
1
15
VAC
WELDVOLTS SPEED
VOLTSSPEED
STRIKE
115VAC
#31
#32
1/2 AMP F501
SET SPEED
SET VOLTAGE
STARTTIMER
CRATER TIMERF2
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