0740 800 097
Valid for serial no. 521--xxx--xxxx to serial no. 005--xxx--xxxx011019
LKB 265/320
Service manual
-- 2 --conte
LIST OF CONTENTS Page
READ THIS FIRST 3................................................................
TECHNICAL DATA 4................................................................
LOAD CHARACTERISTIC 5.........................................................
LKB 265, 400 -- 415 V 6.............................................................
Component description 6...........................................................
Selector switch and suppressor board 6..............................................
Connection diagram 7.............................................................
LKB 265, 230 -- 500 V 8.............................................................
Component description 8...........................................................
Selector switch and primary--voltage connections 8....................................
Connection diagram 9.............................................................
LKB 320, 400 -- 415 V 10.............................................................
Component description 10...........................................................
Selector switches 10................................................................
Connection diagram 11.............................................................
LKB 320, 230 -- 500 V 12.............................................................
Component description 12...........................................................
Selector switches and primary--voltage connections 12..................................
Connection diagram 13.............................................................
DESCRIPTION OF OPERATION, CIRCUIT BOARD AP1 14..............................
1 Power supply 14................................................................
2 Start / Stop 15..................................................................
3 LKB 265 spot welding 16........................................................
4 Wire feed speed 16.............................................................
5 Motor drive / braking 17..........................................................
6 Burn--back time, contactor , gas valve 18..........................................
7 Thermal overload cutout 19......................................................
Component positions, circuit board AP1 21............................................
DIGITAL INSTRUMENT 22............................................................
Calibration 22......................................................................
Component positions on the display board 23..........................................
Connections to the display board 23..................................................
SERVICE INFORMATIO N 24..........................................................
Overheating of diode bridge V1--V6 24................................................
New design of diode bridge V1--V6 25.................................................
INSTRUCTIONS 26..................................................................
INSTALLATION 26..................................................................
INSTRUCTIONS FOR USE 26........................................................
MAINTENANCE 27..................................................................
ACCESSORIES 28..................................................................
SETTI NG THE WIRE FEED PRESSURE 28.............................................
ASSEMBLING INSTRUCTION FOR ACCESSORIES 29..................................
T ransformer set for CO
2
heater 29....................................................
Instrument set 30..................................................................
SPARE PARTS LIST 31..............................................................
NOTES 48..........................................................................
Rights reserved to alter specifications without notice.
-- 3 --clkb0de0
READ THIS FIRST
Maintenance and repair work should be performed by an experienced person, and electrical
work only by a trained electrician. Use only recommended replacement parts.
This service manual is intended for use by technicians with electrical/electronic training for
help in connection with fault--tracing and repair.
Use the connection diagram as a form of index for the description of operation. The circuit
board is divided into numbered blocks, which are described individually in more detail in
the description of operation. All component names in the connection diagram are listed in
the component description.
This manual contains details of all design changes that have been made up to and including
September 2001.
The LKB 265 and LKB 320 are designed and tested in accordance with international
and European standard IEC/EN 60974--1 and 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 INSTRUCTION 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
S Install and earth the welding unit in accordance with applicable s tandards.
S Do not touch live electrical parts or electrodes with bare skin, wet gloves or wet clothing.
S Insulate yourself from earth and the workpiece.
S Ensure your working s tance is safe.
FUMES AND GASES -- Can be dangerous to health
S Keep your head out of the fumes.
S Use 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.
S Protect your eyes and body. Use the correct welding screen and filter lens and wear protective
clothing.
S Protect bystanders with suitable screens or curtains.
FIRE HAZARD
S Sparks (spatter) can cause fire. Make sure therefore that there are no inflammable materials nearby.
NOISE -- Excessive noise can damage hearing
S Protect your ears. Use ear defenders or other hearing protection.
S Warn bystanders of the risk.
MALFUNCTION -- Call for expert assistance in the event of malfunction.
PROTECT YOURSELF AND OTHERS!
-- 4 --
clkb0de0
TECHNICAL DATA
LKB 265
400 -- 415 V
LKB 265
230 -- 500 V
LKB 320
400 -- 415 V
LKB 320
230 -- 500 V
Mains voltage 400--415V
3~ 50/60 Hz
230/400--415/500V
3~ 50 Hz
230/440--460V
3~ 60 Hz
400--415V
3~ 50/60 Hz
230/400--415/500V
3~ 50 Hz
230/440--460V
3~ 60 Hz
Permissible load
100% duty cycle 150 A/22 V 150 A/22 V 195 A/24 V 195 A/24 V
60 % duty cycle 190 A/24 V 190 A/24 V 250 A/27 V 250 A/27 V
30 % duty cycle 265 A/27 V 265 A/27 V 320 A/30 V 320 A/30 V
Operating range 30A/15V--265A/27V 30A/15V--265A/27V 40A/16V--320A/30V 40A/16V--320A/30V
Open--circuit
voltage
15--38 V 15--38 V 16--40 V 16--40 V
Open--circuit power 50 W 50 W 52 W 52 W
Efficiency 0.69 0.69 0.71 0.71
Power factor 0.97 0.97 0.97 0.97
Control voltage 42 V, 50/60 Hz 42 V, 50/60 Hz 42 V, 50/60 Hz 42 V, 50/60 Hz
Dimensions, lxbxh 770x520x620 770x520x620 770x560x640 770x560x640
Weight 92 kg 92 kg 112 kg 112 kg
Enclosure class IP 23 IP 23 IP 23 IP 23
Application class S S S S
LKB 265 and LKB 320 comply with welding machine standard IEC/EN 60974--1 and EN 50199.
The duty cycle refers to the time in per cent of a ten--minute period that you can weld at a certain load
without overloading the welding power source.
The enclosure class indicates the degree of protection against penetration of solid objects and water.
Class IP 23 equipment is designed for indoor and outdoor use.
The
symbol means that the power unit is designed for use in areas of elevated electrical hazard.
Sandard arrangement, LKB 265
Power unit, incorporating spot welding function and adjustable burn--back time. Integral wire
feed unit with feed rollers for 0.8 mm and 1.0 mm solid wire. PSF 250 welding torch with
4.5 m cable. 4.5 m return current cable with return current connector clamp.
3 m mains cable and gas hose.
Standard arrangement, LKB 320
Power unit, fitted with switch for 2/4--stroke control mode selection, with gas pre--flow and
post--flow function in 4--stroke mode and adjustable burn--back time. Integral wire feed unit
with feed rollers for 1.0 mm and 1.2 mm solid wire. PSF 315 welding torch with 4.5 m
cable. 4.5 m return current cable with return current connector clamp.
5 m mains cable and gas hose.
-- 5 --clkb0de0
LOAD CHARACTERISTIC
LKB 265
clkb0p20
LKB 320
clkb0p21
-- 6 --
clkb0de0
LKB 265, 400 -- 415 V
Component description
AP1 Circuit board, see description on page 14. SA1 10--way switch, for s electing welding
voltage
AP2 Suppressor board, see circuit diagram below
Replacing terminal XT1 from serial no.
614--xxx --xxxx
ST1 Thermal oveload cutout, opens at 110 C.
The cutout is mounted on the cooling fins of
the diode bridge.
C1, C2 Capacitor ST2 Thermal overload cutout, opens at 110 C.
The cutout is mounted in the winding of
transformer TM1.
From serial no. xxx--640 -- xxxx
EV1 Fan TC1 Control power supply transformer
HL1 Lamp, white, On/Off TC2 Transformer for CO
2
heater, accessory
KM1 Contactor TC3 Transformer for digital instrument,
accessory
L1 Inductor TM1 Main transformer
M1 Feed unit motor V1--V6 Diode bridge, see page 24 and 25.
P1 Digital instrument, accessory.
See description on page 22.
V7 LED, yellow. Indication, thermal overload
QF1 Switch, On/Off XS1--2 Machine contact
R1 Resistor XS3--10 Sleeve contacts
R2 Varistor XT1--3 Terminal block
RS1 Shunt, accessory YV1 Solenoid valve
Selector switch and suppressor board
Switch positions for selector switch SA1 Circuit diagram and component positions for circuit
board AP2
Connection diagram
When checking the no--load
voltages. Load the machine
with a dummy load of 5.6 kΩ
5 W, connecting it between
plus and minus on the diode
bridge.
-- 7 --clkb0de0
-- 8 --
clkb0de0
LKB 265, 230 -- 500 V
Component description
AP1 Circuit board, see description on page 14. SA1 10--way switch, for s electing welding
voltage
AP2 Suppressor board, see circuit diagram on
page 6. Replacing terminal XT1 from serial
no. 614--xxx--xxxx
ST1 Thermal oveload cutout, opens at 110 C.
The cutout is mounted on the cooling fins of
the diode bridge.
C1, C2 Capacitor ST2 Thermal overload cutout, opens at 110 C.
Mounted in the winding of transformer TM1.
From serial no. xxx--640 -- xxxx
EV1 Fan TC1 Control power supply transformer
HL1 Lamp, white, On/Off TC2 Transformer for CO
2
heater, accessory
KM1 Contactor TC3 Transformer for digital instrument,
accessory
L1 Inductor TM1 Main transformer
M1 Feed unit motor V1--V6 Diode bridge, see page 24 and 25.
P1 Digital instrument, accessory.
See description on page 22.
V7 LED, yellow. Indication, thermal overload
QF1 Switch, On/Off XS1--2 Machine contact
R1 Resistor XS3--10 Sleeve contacts
R2 Varistor XT1--3 Terminal block
RS1 Shunt, accessory YV1 Solenoid valve
Selector switch and primary--voltage connections
Switch positions for selector
switch SA1
Primary voltage connections for transformers TC1, TC2 and
terminal block XT2
Connection diagram
When checking the no--load
voltages. Load the machine
with a dummy load of 5.6 kΩ
5 W, connecting it between
plus and minus on the diode
bridge.
-- 9 --clkb0de0
-- 1 0 --
clkb0de0
LKB 320, 400 -- 415 V
Component description
AP1 Circuit board, see description on page 14. ST1 Thermal overload cutout, opens at 120 C
(110 C before serial no. 005--xxx-- xxxx).
Mounted on the cooling fins of the diode
bridge.
C1, C2
EV1
Capacitor
Fan
ST2 Thermal overload cutout, opens at 130 C.
Mounted in the winding of transformer TM1.
From serial no. xxx--640 -- xxxx
HL1 Lamp, white, On/Off TC1 Control power supply transformer
KM1 Contactor TC2 Transformer for CO
2
heater, accessory
L1 Inductor TC3 Transformer for digital instrument,
accessory
M1 Feed unit motor TM1 Main transformer
P1 Digital instrument, accessory.
See description on page 22.
V1--V6 Diode bridge, see page 24 and 25..
QF1 Switch, On/Off V7 LED, yellow. Indication, thermal overload
cutout
R1 Resistor XS1--2 Machine contact
R2 Varistor XS3--10 Sleeve contacts
RS1 Shunt, accessory XT1--3 Terminal block
SA1 4--way switch, for selection of welding
voltage
YV1 Solenoid valve
SA2 10--way switch, for s election of welding
voltage
Selector switches
Switch positions for selector switches SA1 and SA2
Connection diagram
When checking the no--load
voltages. Load the machine
with a dummy load of 5.6 kΩ
5 W, connecting it between
plus and minus on the diode
bridge.
-- 1 1 --clkb0de0
-- 1 2 --
clkb0de0
LKB 320, 230 -- 500 V
Component description
AP1 Circuit board, see description on page 14. ST1 Thermal overload cutout, opens at 120 C
(110 C before serial no. 005--xxx-- xxxx).
Mounted on the cooling fins of the diode
bridge.
C1, C2
EV1
Capacitor
Fan
ST2 Thermal overload cutout, opens at 130 C.
Mounted in the winding of transformer TM1.
From serial no. xxx--640 -- xxxx
HL1 Lamp, white, On/Off TC1 Control power supply transformer
KM1 Contactor TC2 Transformer for CO
2
heater, accessory
L1 Inductor TC3 Transformer for digital instrument,
accessory
M1 Feed unit motor TM1 Main transformer
P1 Digital instrument, accessory.
See description on page 22.
V1--V6 Diode bridge, see page 24 and 25..
QF1 Switch, On/Off V7 LED, yellow. Indication, thermal overload
cutout
R1 Resistor XS1--2 Machine contact
R2 Varistor XS3--10 Sleeve contacts
RS1 Shunt, accessory XT1--3 Terminal block
SA1 4--way switch, for selection of welding
voltage
YV1 Solenoid valve
SA2 10--way switch, for s election of welding
voltage
Selector switches and primary--voltage connections
Switch positions for selector
switches SA1 and SA2
Primary voltage connections for transformers TC1, TC2 and
terminal block XT2
Connection diagram
When checking the no--load
voltages. Load the machine
with a dummy load of 5.6 kΩ
5 W, connecting it between
plus and minus on the diode
bridge.
-- 1 3 --clkb0de0
-- 1 4 --
clkb0de1
DESCRIPTION OF OPERATION, CIRCUIT BOARD AP1
WARNING !
STATIC ELECTRICITY can damage circuit
boards and electronic components.
S
SS
S Observe precautions for handling electrostatic
sensitive devices.
S
SS
S Use proper static--proof bags and boxes.
ESD
Sections 1--11 below refer to the diagrams on pages 6 -- 13.
1 Power supply
The circuit board uses two different supply voltages: 16 V f or the electronics and
42 V for power supply to the motor, contactor and gas valve.
clk b0e05
S Power supply to the electronic circuitry
The 16 V power supply from transformer TC1 is rectified by diodes D3--D6 and
regulated to 15 V by voltage regulator VR1.
S 42 V power supply
A_42VAC and B_42VAC are used as control power supplies for the contactor and
gas valve. Indicating lamp HL1 is mounted on the front of the machine and shows
that the power is turned on.
The supply is rectified by diode bridge BR1. The output voltage (60 V) supplies the
wire feed unit motor.
-- 1 5 --clkb0de1
2 Start / Stop
clk b0e07
Closing contact SB1 on the welding torch starts the welding process. The LKB 265
provides only two--stroke control mode: the LKB 320 provides a choice of
two--stroke or four--stroke control modes.
T1
0
0
0
0
1
1
1
1
Gas valve
W
e
l
ding gun
trigger switch
Wire feed
Contactor
T1 = Burn--back time
T1
Start-- stop sequence, 2--stroke (LKB 265 and LKB 320)
LKB 320
Switch SW1 selects between 2--stroke and 4--stroke control mode.
clkb0e09
S Connection o f pins 2 and 3 in switch SW1 selects 2--stroke control mode.
-- 1 6 --
clkb0de1
S Connection o f pins 2 and 1 in switch SW1 selects 4--stroke control mode.
T1
0
0
0
0
1
1
1
1
Gas valve
W
e
l
ding gun
trigger switch
Wire feed
Contactor
T1 = Burn--back time
Start-- stop sequence, 4--stroke (LKB 320)
3 LKB 265 sp ot welding
clk b0e08
The LKB 265 has a spot--welding capability, which the LKB 320 does not. It is
active when the switch in potentiometer RP2 is closed. Spot welding time is
adjustable between 0.2 and 2.5 seconds.
If the welding torch trigger switch is released while a spot weld is being made, the
welding sequence will be interrupted.. If the switch is held closed for longer than
the spot weld time, welding stops when the spot weld time is up. To restart, the
switch must be released and then operated again.
4 Wire feed speed
The wire feed speed adjustment range is 1.9 to 19 metre/minute.
clkb0e06
The +5.1 V refer ence voltage (1 % ) is derived from the PWM circuit, which
generates gate pulses for the motor dr ive transistor.
-- 1 7 --clkb0de1
5 Motor drive / braking
clkb0e12
red
black
The motor is powered by the smoothed +60 V supply. Pulse width modulation of
transistor Q5 controls the motor voltage. The pulse frequency is about 9 kHz, and
maximum conduction time of the pulses is about 98 % of the pulse cycle time.
During the Off parts of the pulse cycle, the motor current freewheels through diode
D35.
At 24 V motor supply voltage, the wire feed roller speed is 160 r/min 5%. Ata
roller speed of 200 r/min, the wire feed speed is 19 m/min 5%.
S Speed control
The gate pulses to transistor Q5 are generated by a PWM circuit. Resistors R84 and
R85 form a potential divider, providing a voltage signal that is pr oportional to the
wire speed. The PWM circuit compares the set speed with the actual speed.
S Current limit
The current limit is set at 5.5 A. The motor current is measured by resistor R68,
which produces a voltage drop proportional to the current (1 A = 100 mV). The
current limit restricts t he conduction time of the gate pulses to transistor Q5.
S Braking
When the motor starts, capacitor C22 charges via diode D18. The voltage is limited
to 15 V by zener diode D13. The LED in optocoupler IC4 is activated when braking
is requir ed, connecting C22 (15 V) to the gate of transistor Q3. The tr ansistor
conducts and short--cir cuits the motor voltage via resistors R69 and R70, which limit
the braking current to about 20 A.
-- 1 8 --
clkb0de1
6 Burn--back time, co n t acto r, gas valve
clkb0e11
S Burn--back time
The burn--back time is the time from when motor braking starts until the main
contactor opens. When welding stops, capacitor C38 is discharged through
potentiometer R21. The time can be adjusted from 0 to 0.25 seconds.
S Energising the contactor
The contactor is controlled by triac TC2.
S Gas valve
The gas valve is connected to board contacts A5 and A6.
S LKB 265
The valve receives its power supply from triac TC2 via resistor R20 (0τ).
S LKB 320
The valve receives its power supply from triac TC1.
-- 1 9 --clkb0de1
7 Thermal overload cutout
The thermal overload cutout ST1 is mounted on the cooling fins of the diode bridge,
and operates at a temperature of 110 C in both machines.
The thermal overload cutout ST2 is mounted in the winding of transformer TM1,
and operates at a temperature of 110 C in LKB 265 and at 130 C in LKB 320.
The overload cutout ST2 is mounted from machine number XXX 640 XXXX.
A current normally flows through the cutouts f rom the +20 V supply via R2 and D2,
and from the +15 V supply via R8. The voltage at contact C1 is kept low by the
switch. If a cutout operates, C1 goes high and the output signals from the boar d are
disabled.
Operation of the cutout causes a current to flow from +20 V to 0 V via R2, D1 and
LED V7, which indicates operation of the cutout.
-- 2 0 --
clkb0de1
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