ESAB LKA 150 User manual

0349 300 001 Valid for serial no. 923−xxx−xxxx040928
LKA 150
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Service manual

INTRODUCTION 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
RATING PLATE 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
COMPONENT DESCRIPTION, LKA 150 4. . . . . . . . . . . . . . . . . .
CONNECTION DIAGRAM, LKA 150 5. . . . . . . . . . . . . . . . . . . . .
CIRCUIT DIAGRAM, CIRCUIT BOARD AP1 6. . . . . . . . . . . . . .
COMPONENT POSITIONS, CIRCUIT BOARD AP1 7. . . . . . . .
DESCRIPTION OF OPERATION, CIRCUIT BOARD AP1 7. . .
MOTOR DIAGRAMS 10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
LOAD CHARACTERISTIC, LKA 150 11. . . . . . . . . . . . . . . . . . . . .
TECHNICAL DATA 12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
INSTALLATION 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
OPERATION 14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MAINTENANCE 14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
WELDING DATA SELECTION 15. . . . . . . . . . . . . . . . . . . . . . . . . .
SPARE PARTS LIST, LKA 150 16. . . . . . . . . . . . . . . . . . . . . . . . . .

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INTRODUCTION
This service manual is intended for use by technicians with electrical training when carrying
out fault tracing and repair of the equipment.
At the end of the manual, there is a brief guide to using the machine in order to assist in
understanding the machine.
The manual contains all design modifications introduced up to and including September
2004.
Use the diagrams in the manual when tracing faults. The machine components are described
in alphabetical order on the pages foregoing the connection diagram.
The LKA 150 is designed and tested in accordance with international standard
EN 60974−1, EN 50199.
On completion of service or repair work, it is the responsibility of the person(s) etc.
performing the work to ensure that the product does not depart from the requirements
of the above standard.
WARNING
READ AND UNDERSTAND THE OPERATING MANUAL BEFORE INSTALLING OR OPERATING.
ARC WELDING AND CUTTING CAN BE INJURIOUS TO YOURSELF AND OTHERS. TAKE PRECAU-
TIONS WHEN WELDING. ASK FOR YOUR EMPLOYER’S SAFETY PRACTICES WHICH SHOULD BE
BASED ON MANUFACTURERS’ HAZARD DATA.
ELECTRIC SHOCK −Can kill
SInstall and earth the welding unit in accordance with applicable standards.
SDo not touch live electrical parts or electrodes with bare skin, wet gloves or wet clothing.
SInsulate yourself from earth and the workpiece.
SEnsure your working stance is safe.
FUMES AND GASES −Can be dangerous to health
SKeep your head out of the fumes.
SUse ventilation, extraction at the arc, or both, to keep fumes and gases from your breathing zone and
the general area.
ARC RAYS −Can injure eyes and burn skin.
SProtect your eyes and body. Use the correct welding screen and filter lens and wear protective
clothing.
SProtect bystanders with suitable screens or curtains.
FIRE HAZARD
SSparks (spatter) can cause fire. Make sure therefore that there are no inflammable materials nearby.
MALFUNCTION −Call for expert assistance in the event of malfunction.
PROTECT YOURSELF AND OTHERS!
Rights reserved to alter specifications without notice.

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RATING PLATE
The rating plate is secured to the back of the machine. The plate is shown below, with an
explanation of how it should be read and interpreted.
1. LKA 150 is the type designation for this power source. The first letter, L, indicates that
the LKA 150 is a rectifier, while K indicates Compact (Kompakt in Swedish) and A indi-
cates the design generation.
The 150 indicates the maximum welding current.
2. These symbols indicate that the LKA 240 incorporates a transformer and rectifier.
3. This section indicates the voltage/current characteristic for MMA welding and a current
range of 20 −100 A.
The voltage values of 15 and 19 V in the heading indicate that we comply with the in-
ternational arc characteristic as defined in IEC 974−1.
X = The duty cycle, indicating for how long a time welding can be carried out at the
specified welding data, expressed as a percentage of a ten−minute period.
I2= The current at the respective duty factors.
U2= The arc line characteristic voltage.
Uo= The open−circuit voltage.

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4. Indicates that the unit is intended for connection to a 230 V single−phase 50 Hz supply.
I1= primary currents at the various load points.
5. IP21 indicates the enclosure class in respect of protection against penetrating objects and
water. Enclosure class IP21 indicates that the equipment is intended for indoor use,
while IP23 equipment is also suitable for outdoor use.
The symbol indicates that the machine is designed for use in areas of elevated electri-
cal risk.
6. The machine’s serial number, in the form of three groups of figures (xxx yyy zzz).
The first group (xxx) indicates the version. The figures represent the year and week of
approval of the version.
The second group (yyy) shows the year and week of final testing of the machine.
The second group (yyy) shows the year and week of final testing of the machine. For
example, 341 indicates Week 41, 1993.
The final group (zzz) consists of three or four figures, and is a serial number in the range
0001 to 9999.
7. Shows that ESAB complies with the international standard, IEC 974−1.

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COMPONENT DESCRIPTION, LKA 150
AP1 Circuit board with control electronics: see the diagram on page 6 and description
on page 7.
C1 Capacitor 0.1µF, 400 VDC, transient protection.
C2 Capacitor 0.1µF, 400 VDC, transient protection.
L1 Inductor.
M1 Wire feeder motor.
QF1 Switch, 8−way, for 7−step and Off (main On/Off switch) adjustment of the welding
current.
For the Australian market the main On/Off part of the switch is 2−pole.
SB1 Welding torch trigger switch.
ST1 Thermal overload cutout, for protection against overload, fitted in the winding of
main transformer TM1.
The switch operates (opens) at a temperature of 130 °C.
ST2 Thermal overload cutout, for protection against overload, fitted on the diode bridge
cooling fins (VC1). It operates (breaks) at 110 °C.
TM1 Main transformer
V1 LED, yellow.
Lights if thermal overload cutouts ST1 or ST2 operate as a result of high
temperature.
VC1 Diode bridge.
XS1 2−pole connector.
XS2 5−pole connector.
XS3 2−pole connector.
XS4 Connector, 2−pole.
XT1 Mains terminal block, 2−pole.
XT2 Terminals, welding current, positive and negative

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CONNECTION DIAGRAM, LKA 150

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CIRCUIT DIAGRAM, CIRCUIT BOARD AP1

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COMPONENT POSITIONS, CIRCUIT BOARD AP1
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DESCRIPTION OF OPERATION, CIRCUIT BOARD AP1
This description relates to the circuit diagram and the component positions diagram.
If the circuit board is faulty, it must be replaced.
1CONTROL CIRCUIT
Pressing trigger switch SB1 on the welding torch energises relay RE1 from control
power transformer TR1. The contacts on the relay connect main transformer TM1 to
the mains power supply.
The power supply to RE1 is half−wave rectified by D1. Resistor R1 is connected in
series with the relay and drops the voltage to it. Capacitor C1 (220µF) smoothes the
voltage. It also delays the drop−off of relay RE1 by about 25 ms, to provide a
back−burn time.
2THERMAL OVERLOAD CUTOUT
In the event of a thermal overload, thermal overload cutouts ST1 or ST2 interrupt the
secondary circuit from TR1, causing relay RE1 to drop off and de−energising the
welding circuit.
When not operated (i.e. with closed contacts), the cutouts short−circuit inputs
B6 and B7.
Operation of either of the cutouts is indicated by LED V1. Interruption of the cutout
circuit energises the LED via D2, R3 and D3. D2 is a half−wave rectifier, R3 limits
the current through the LED and D3 protects it against reverse voltage.

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3RFI SUPPRESSION AND BASE LOAD RESISTORS
Capacitors C4 −C6 protect against RFI. Resistors R12 and R15 provide a minimum
base load for the rectifier bridge: in addition, they act as discharge resistors for the
capacitors.
4MOTOR DRIVE CIRCUIT
The wire feed motor is powered by the rectified secondary voltage from main
transformer TM1.
Pressing the welding torch trigger switch SB1 provides a supply to thyristor TY1 via
contact B4 from the positive side of the main power rectifier VC1.
Resistors R10 and R14 limit the motor starting current: excessive starting current
would demagnetise the motor. D9 is a squelch diode protecting against back−emf
from the motor.
The ignition circuit for TY1 consists of R2, R4, R5, D5 and C2.
When Q1 is not conducting, operation of the circuit is as follows:
If the voltage at B4 exceeds the motor voltage, C2 charges via R2, R4 and R5.
When the voltage on C2 reaches the trigger voltage (0.5 −1.5 V), thyristor TY1 fires.
This means that TY1 conducts each half−cycle when Q1 is not conducting.
D5 protects C2 against negative voltage when Q1 conducts.
MOTOR VOLTAGE CONTROL
C3, R11 and potentiometer R13 form a low−pass filter circuit for the motor supply.
R13 picks off a suitable fraction of the motor voltage for connection to the base of Q1
via diode D6. Q1 starts to conduct at a bases voltage of 0.7 V.
C2 charges more slowly, which means that thyristor TY1 fires later.
Motor voltage is lowest when R13 is in its upper position, the minimum position.
The base voltage is then high and Q1 conducts. The charging time for C2 becomes so
long that thyristor TY1 misses some half cycles, firing only (for example) on every
third cycle.
When R13 is in its lower (= maximum) position, the base voltage on Q1 is low and
Q1 does not conduct. In this state, zener diode D7 determines the maximum motor
voltage.
See on page 10 for the motor voltage and current waveforms.

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CIRCUIT DIAGRAM, CIRCUIT BOARD AP1

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MOTOR DIAGRAMS
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Motor voltage and current when R13 is at its minimum position and QF1 is in position 3.
The motor is unloaded.
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Motor voltage and current when R13 is in its maximum position and QF1 is in position 3.
The motor is unloaded.

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LOAD CHARACTERISTIC, LKA 150
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TECHNICAL DATA
Load capacity
At 8% duty cycle 150 A / 16 V
At 60% duty cycle 55 A / 17 V
At 100% duty cycle 40 A / 16 V
No−load voltage 16 −28 V
Wire feed speed 2,5 −15 m/min
Wire sizes
Non−alloyed 0,6 −0,8 mm
Stainless 0,6 −0,8 mm
Aluminium 1,0 mm *
Gasless wire 0,8 mm
* Teflon wire guide, feed roller for 1.0 mm wire and contact tip for 1,0 mm wire are required.
Voltage steps 7
Wire bobbin capacity 1 −5 kg (maximum spool diameter 200 mm)
Power supply
Voltage 230 V
Primary current 22 A
Frequency 50 Hz
Fuse 10 A slow−blow **
Mains cable, area 3 x 1,5 mm2
** See also ’INSTALLATION’ on page 13.
Enclosure class IP21
Application class
Weight 36 kg
Dimension drawing
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INSTALLATION
To be able to operate the LKA 150 at maximum power (position 7), it must be supplied via a
16 A slow−blow fuse. However, a 10 A slow−blow fuse is sufficient for welding at currents
up to about 100 A.
SPlace the machine in a suitable position and check that cooling is not obstructed.
SCheck that the mains voltage is 230 −240 V.
Make the necessary earth connections in accordance with safety regulations.
SFit the filler wire as shown below.
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If the drive rollers slip or wire feed does not work properly, it may be necessary to adjust the
roller pressure, as shown in Figure 5 above.
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SOLID WIREGASLESS WIRE
When welding with gasless wire, the return current cable must be connected to the positive
terminal on the terminal block above the wire feed unit.

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OPERATION
SConnect the return current conductor clamp (E)
to the workpiece.
SWhen welding with solid wire, open the gas valve (A) on
the gas bottle and adjust the gas flow by reducer valve (B).
The gas flow must be 8 −12 litres per minute.
STurn on the power unit and set a suitable voltage
with knob (H).
SHold the welding torch trigger switch (D) pressed
until filler wire is fed out through the contact tip (F).
SSelect suitable welding data with the voltage cont-
rol selector (H) and the wire feed control knob (J),
as shown in the table on page 15.
SStart welding. Adjust the settings if necessary.
SThe yellow LED (G) on the front panel will light if the thermal
overload cutout operates as a result of overload.
The overload cutout resets automatically when the machine has cooled to a safe tempera-
ture.
MAINTENANCE
SCleaning away dust
Blow the unit clean with compressed air at reduced pressure.
SWire feed mechanism
The wire feed mechanism should be cleaned, and wearing parts replaced, at regular inter-
vals in order to ensure smooth, reliable wire feed.
Do not tension the pressure roller too hard, as this will result in abnormal wear to the
pressure roller, the feed roller and the wire guide.
SWelding torch
Blow the wire guide clean and clean the gas nozzle at regular intervals.

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WELDING DATA SELECTION
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SPARE PARTS LIST, LKA 150
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Edition 040928
Ordering no. Denomination Notes
469 375−880 LKA 150
469 375−881 LKA 150 Only for the Danish market
Position 205 deviates from version −880
469 375−882 LKA 150 Only for the Australian market
Position 102, 201 and 205 deviates from version −880
469 375−883 LKA 150 Only for the British market
Position 205 deviates from version −880
Spare parts list - Reservdelsförteckning - Ersatzteilverzeichnis - Liste de pièces détachées
Spare parts are to be ordered through the nearest ESAB agency as per the list on the back of the cover. Kindly indicate type of unit, serial number,
denominations and ordering numbers according to the spare parts list.
Reservdelar beställs genom närmaste ESAB−representant, se sista sidan. Vid beställning var vänlig uppge typ och tillverkningsnummer samt
benämningar och beställningsnummer enligt reservdelsförteckningen.
Die Ersatzteile können bei der nächsten ESAB−Vertretung bestellt werden, siehe letzte Seite. Bitte geben Sie Typenbezeichnung und
Herstellungsnummer sowie Bezeichnungen und Bestellnummern laut Ersatzteilverzeichnis an.
Au dos de la brochure, vous trouverez l’adresse du représentant ESAB le plus proche. Prière de lui adresser votre commande, après avoir pris le
soin de mentionner le type et le numéro de série de l’unité ainsi que le numéro de commande et la désignation conformément á la liste de pièces
détachées.

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C = component designation in the circuit diagram
Item
no Qty Ordering no. Denomination Notes C
101 1 469 358−001 Cover plate
102 1
1
469 356−001
469 821−001
Rear panel
Rear panel Only for the Australian market
103 1 469 386−001 Side panel With text
104 1 0700 200 001 Welding gun MXL 150v Complete
107 1 469 571−880 Return cable Complete
108 1 469 360−001 Front panel
110 2
2
2
469 478−001 Link wheel
Screw
Washer
M6 x 16 mm
D 6,5/16,5
111 1368 265−001 Securing strap
112 1193 498−104 Connector XS4
113 1193 498−107 Connector
114 1Inlet nozzle See item 150
115 1Pressure arm With pressure roller, See item 150
117 1Feed roller See item 150 and 151
118 1469 475−880 Wire feed unit Complete
120 2 469 391−001 Attachment
121 1 469 390−001 Shaft
122 2 Washer D 10.5/22
123 2 192 859−115 Locking washer
124 2 469 467−001 Wheel
125 1 469 310−880 Brake hub Complete (1 −5 kg)
126 1
2
469 437−001 Handle
Screw M6 x 16 mm
SPARE PARTS SETS
Item Ordering no. Denomination Notes
150 469 517−880 Spare parts set Contains items 114, 115, 117 feed roller 0.6/0.8 and a tool for the
feed roller
151 469 517 880
469 517−881 Feed roller 0.6/0.8 1.0/1.2
152 155 716−880 Gas flow gauge For protection gas