ESAB LKB 265 User manual

0740 800 097

Valid for serial no. 521--xxx--xxxx to serial no. 005--xxx--xxxx011019

LKB 265/320

Service manual

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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.

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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!

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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.

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LOAD CHARACTERISTIC

LKB 265

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LKB 320

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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.

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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.

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-- 1 0 --

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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 --

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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 --

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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

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.

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S Connection o f pins 2 and 3 in switch SW1 selects 2--stroke control mode.

-- 1 6 --

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S Connection o f pins 2 and 1 in switch SW1 selects 4--stroke control mode.

T1

0

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 --

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6 Burn--back time, co n t acto r, gas valve

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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.

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