ESAB LKB 220S is a versatile welding machine capable of handling a wide range of welding applications. It features precise wire feed speed control for consistent welds and a "creep speed" function for starting welds with reduced spatter. The LKB 220S also includes a built-in spot welding function with adjustable timing for precise welds. With its user-friendly controls and rugged construction, this machine is well-suited for professional welding tasks.
ESAB LKB 220S is a versatile welding machine capable of handling a wide range of welding applications. It features precise wire feed speed control for consistent welds and a "creep speed" function for starting welds with reduced spatter. The LKB 220S also includes a built-in spot welding function with adjustable timing for precise welds. With its user-friendly controls and rugged construction, this machine is well-suited for professional welding tasks.
0349 300 027
010126
LKB 220S
Service manual
2
1. CONNECTION DIAGRAM, LKB220S, 400V ....................................................................................... 4
2. COMPONENT POSITIONS, CIRCUIT BOARDS:
A. LKC22 (A1) ...................................................................................................................................
B. QSyn-Meter 20 (A2) ......................................................................................................................
6
6
3. CONTROL CIRCUIT FUNCTION ........................................................................................................ 7
3.1 POWER SUPPLY ....... .................................................................................................................... 7
3. 2 START / STOP ........................................................................... .................................................... 8
3. 3 SPOT WELDING ............................................................................................................................. 8
3. 4 WIRE FEED SPEED / SOFT START ..............................................................................................8
3. 5 MOTOR CONTROL ....................................................................................................................... 9
3. 6 BURNBACK TIME, CONTACTOR, GAS VALVE .......................................................................... 10
3. 7 THERMAL OVERLOAD CUTOUT ................................................................................................. 10
3. 8 CONTROL MODES – 2-STROKE/MOTOR TEST/4-STROKE ...................................................... 11
3.9 MEASURING AND DISPLAYING OF WELDING PARAMETERS
A) U/I – MEASUREMENT INPUTS ......................................................................................................
B) PARAMETERS DISPLAYING AND DISPLAY – MODE SELECTION ...........................................
11
12
3.10 SYNERGY CONTROL PRESETTINGS AND INDICATIONS
A) OFF/ON AND MATERIAL/GAS – SELECTION .............................................................................
B) WIRE DIAMETER PRESETTING ...................................................................................................
C) WELDING VOLTAGE SELECTION ................................................................................................
D) INDICATION OF SYNERGY CONTROL STATUS .........................................................................
13
13
13
14
4.TECHNICAL DATA ............................................................................................................................... 15
5. LOAD CHARACTERISTIC ................................................................................................................... 15
6. INSTALLATION .................................................................................................................................. 16
7. INSTRUCTION FOR USE .................................................................................................................... 16
8. MAINTENANCE ................................................................................................................................... 17
9. ACCESORIES ...................................................................................................................................... 18
9.1 TRANSFORMER SET FOR CO
2
–HEATER ................................................................................. 18
10. SPARE PARTS LIST ......................................................................................................................... 19
INTRODUCTION
This service manual is intended for use by technicians with electrical training. Use it for fault - tracing and
repair.
Use the diagrams in section 1 and the description of operation in section 3 respectively – when fault-tracing.
A brief user guide is included in section 7 to assist understanding how the machine is used.
The manual contains details of design up to and including September 2000.
3
! WARNING !
ARC WELDING AND CUTTING CAN BE INJURIOUS TO YOURSELF AND OTHERS. TAKE
PRECAUTIONS WHEN WELDING. ASK YOUR EMPLOYER FOR SAFETY PRACTICES THAT SHOULD
BE BASED ON MANUFACTURER’S HAZARD DATA.
ELECTRIC SHOCK - Can kill
- Install equipment in accordance with obligatory standards.
- Do not touch live electrical parts or electrodes with bare skin, wet gloves or wet clothes.
- Insulate yourself from earth and workpiece.
- Ensure your work position is safe.
FUMES AND GASES - Can be dangerous to your health
- Keep your head away from fumes.
- Use ventilation and/or extraction to keep fumes and gases away from your breathing zone
and surroundings.
ARC RAYS - Can injure eyes and burn skin
- Protect your eyes and skin. Use correct welding screens, filter lens and wear protective clothes.
- Protect bystanders with suitable screens or curtains.
FIRE HAZARD
- Sparks (spatter) can cause fire. Make therefore sure there are no inflammable materials nearby.
NOISE - Excessive noise can damage your hearing.
- Protect your ears. Use ear defenders or other hearing protection.
- Warn bystanders of the risk.
READ AND UNDERSTAND THE INSTRUCTION MANUAL BEFORE INSTALLING OR OPERATING UNIT
PROTECT YOURSELF AND OTHERS !
4
1.
CONNECTION DIAGRAM, LKB220S, 400V
Switch positions for switch Q2 Switch positions for switch Q3
COMPONENT DESCRIPTION
A1 Circuit board LKC22 M1 Fan
A2 V/A - meter M2 Drive unit motor
T1 Transformer V2 Rectifier bridge
V1 Diode bridge B1 Temperature switch
L1 Inductor
R2 Resistor 0,6 Ω
RI Shunt S1 Welding gun – trigger switch
K1 Contactor RP1 Wire speed reference potentiometer
Q1 Rotary cam switch RP2 Spot-welding potentiometer
Q2 Rotary cam switch H1/H2, H3/H4 LED (green/red)
Q3 Rotary cam switch H5, H6 LED (green)
T2 Control transformer T3 Transformer
C1,C2,C3 Capacitor 0,1uF/275V F4 Fuse 4A slow-block
R1 Resistor 3,3k 1W XG Terminal block
F1,F3 Fuse 2,5A slow-blow
F2 Fuse 6,3A slow-blow
5
LKB220S
400-415V ~3 50/60Hz
6
LKB220S
230V ~3 50/60Hz
7
2.
COMPONENT POSITIONS, CIRCUIT BOARDS
A. LKC22 (A1)
8
B. QSyn-Meter 20 (A2)
3. CONTROL CIRCUIT FUNCTION
LKB 220S (equipped with PCBs: LKC22 & QSYN-Meter 20) – may work in 2 control modes:
- standard control (welding parameters set manually)
- “synergy” control (welding parameters partially stored in microprocessor program)
[For more details – see section 7].
Sections 3.1 – 3.10 below refer to the diagrams in chapter 1.
3.1 POWER SUPPLY
The circuit board uses one supply voltage: 31VAC – rectified by the bridge V2 for power supply to the motor
and control circuitry.
• Power supply to the electronic circuitry
- the +42VS power supply from diode V1 through R1A, R1 – is regulated to 15V by voltage regulator A1,
- the +42VS from V1 through R3, V3A, R4 is regulated to +5V by voltage regulator A2,
- +15V is used for powering of motor control electronic
9
- +5V – supplies microprocessor control circuits
• +42V/+42VS power supply
+42V – is used for motor control and indication (LED - on front panel)
+42VS – is used for powering of some input control circuits (see next sections)
These voltages may vary (with load/mains voltage deviation) – from –15% to +10%.
• +26V (intermediate voltage for A2) – is also used for powering of relays K1 and K2 (on PCB)
3. 2 START/STOP
Closing contact S1 on the welding torch starts the welding process – or only motor M2 depending on control
mode selection (see – section 3.8)
3. 3 SPOT WELDING
The LKB 220S has a spot–welding capability. It is active when the switch in potentiometer RP2 is closed.
Spot welding time is adjustable between 0,5 and 4 seconds.
If the welding torch trigger switch is released while a spot weld is being made, the welding sequences 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.
3. 4 WIRE FEED SPEED / SOFT START
The wire feed speed setting range is 1,4 to 19 meter/minute, the upper speed may be adjusted by R51A.
10
There is built-in „creep-speed” function in the program (ca 50% of work speed) -i.e. welder starts welding with
reduced wire speed and when the welding current reaches value – ca 7A - the speed rise up automatically to
the value pre-set by RP1.
V-REF voltage is reference signal for motor speed control circuit.
In “standard” control mode (-Synergy = OFF by switch “K” – in the motor compartment) – welder may set the
wire speed in full range by the potentiometer RP1. When “synergy” control mode is active – signal from RP1
serves only as corrective value ±10% of the pre-set value of speed (by the microprocessor program).
[Note: Correction is counted from the middle point of RP1].
3. 5 MOTOR CONTROL
The motor is powered by the smoothed +42 V supply. Pulse width modulation of transistor V8 controls the
motor voltage. The pulse frequency is about 16 kHz, and maximum conduction time of the pulses is about
95% of the pulse cycle time. During the Off parts of the pulse cycle, the motor current freewheels through
diode V10.
At 24V motor supply voltage, the wire feed roller speed is 160 r/min ±5%. At a roller speed of 200r/min, the
wire feed speed is 19 m/min ±5%.
• Speed control
The gate pulses to transistor V8 are generated by a PWM circuit, which compares speed reference from
microprocessor electronic with signal proportional to the motor voltage (R10, R24).
• Current limit
The current limit is set at 6,0 A. The motor current is measured by resistor R32 which produces a voltage
drop proportional to the current (1A = 33mV). The current limit restricts the conduction time of the gate
pulses to transistor V8.
• Compensation of motor I x R voltage
11
Current signal allows to compensate voltage drop on motor armature resistance so as to improve wire
transportation at low speed settings (there is no adjusting element).
3. 6 BURNBACK TIME, CONTACTOR, GAS VALVE
• BURNBACK TIME
The burnback time is the time from when motor braking starts until the main contactor opens. The
burnback time can be adjusted from 0 to 0,35 seconds – by the potentiometer R47 (signal to the
microprocessor electronic). R47 is located in the drive unit – compartment (pos. M).
• ENERGISING THE CONTACTOR AND GAS VALVE
Contactor is switched-on by relay K1, which is controlled by transistor V14; gas valve Y1 is controlled by
V12 and K2.
3. 7 THERMAL OVERLOAD CUTOUT
The thermal overload cutout B1 is mounted on the surface of the T1 transformer winding – and operates at a
temperature of 90°C.
When B1 operates (contact opens) – alarm - signal is applied to the D3 and the output signals from the board
are disabled and red LED indicates the overload.
When the equipment cool-down – B1 resets automatically.
NOTE: Both LED (Power ON and OVERLOAD) are located in common case, so the mixed light green and
red is seen as orange colour – when the overload is indicated!
12
3. 8 CONTROL MODES – 2-STROKE/MOTOR-TEST/4-STROKE
By the switch S1 on the PCB (pos. N – in the motor compartment – welder may select the following control
modes:
A) 2-STROKE CONTROL
When the trigger switch (welding gun-S1) is depressed – welding process starts (wire feed motor, gas
valve and power unit contactor).
When trigger switch is released – welding process stops (motor and gas valve – immediately, contactor –
when burnback time is elapsed).
B) MOTOR TEST
When trigger switch is closed – only feed motor starts, gas valve and contactor remain disenergised.
C) 4-STROKE CONTROL
The welding process is controlled by trigger switch S1 (welding gun) – as shown below:
NOTE: On the LKC22 – for selected 2-S/4-S mode – active signal is low, it means that for “motor - test” –
both signals are high.
13
3. 9 MEASURING AND DISPLAYING OF WELDING PARAMETERS
A) U/I – MEASURMENT INPUTS
Negative voltage (maximum 60V!) and positive 60mV shunt signal are applied to the LKC22. These signals
are converted into pulse – frequency signals (FU* and FI* respectively) – which are processed by
microprocessor electronic.
FU* - frequency is 6,4 kHz for - 40V input (adj. by R97),
FI* - frequency is 4,0 kHz for +60mV input (adj. by R88),
(signals on TP7 and TP8 are referred to TP6!)
B) PARAMETERS DISPLAYING AND DISPLAY MODE SELECTION
Machine LKB220S is equipment with 2-row display – located in the PCB A2 (Qsyn-Meter20), which
includes 2 selectors for choosing of displayed parameters.
By SV1 (upper toggle switch) –U[V] or I[A] display is selected (open contact correspondents to I[A]!).
By SV2 – recommended thickness of welded material [mm] or reference wire speed [m/min] – is selected
for displaying (open contact corresponds to [m/min]!).
Display “QSyn-Meter20” operates in 3 modes:
1) Before start of welding (bright indicators!); there are displayed prospective (expected) values of U or I
(only in “synergy –mode”) – and recommended thickness or speed reference.
2) During welding (bright indicators) – actual values of U or I
3) After stop of welding (dimmed indicators) – memorised values of U and I (“HOLD”- function)
14
3. 10 SYNERGY CONTROL PRE-SETS AND INDICATIONS
A) OFF/ON AND MATERIAL /GAS SELECTION
10-position selector S2 on the LKC22 (pos. K – in the motor compartment) – serves for selection of control
mode: 1-st position = “SYNERGY-OFF” (i.e. – “STANDARD” control mode), remaining positions
correspond to “SYNERGY” control mode, - for different sets of electrodes – material and shield gases.
(Note: S2 output is BCD-coded)
B) WIRE DIAMETER PRESETTING
Pre-setting of wire electrode diameter is performed by the potentiometer R61 (pos. L – in the motor
compartment).
C) WELDING VOLTAGE SELECTION
Welder may select required value of welding voltage by Q2 – and Q3 – switches. Each position is identified
by microprocessor so as to determine welding parameter.
15
D) INDICATION OF SYNERGY CONTROL STATUS
Depending on the parameter pre-sets made by welder (voltage, material/gas, wire diameter) –
microprocessor determines and displays necessary data and signals.
When the combination of the pre-sets is incorrect – red LED (“SYNERGY”) warns the operator and all
control function are disabled.
When pre-sets are acceptable (but not optimal) – green LED (“SYNERGY”) flashes – i.e. welding is
possible but not recommended, for correct pre-sets – green LED lights continuously.
When welding functions are enabled – there are displayed prospective welding parameters (see – section
3.9B) and also green LED indicates recommended inductance output (Lmin, Lmax) for the current wire.
16
4.TECHNICAL DATA
400-415V, 3~50/60 Hz 230V, 3~50/60 Hz
Mains voltage 3x400-415V, 3~50/60 Hz 3x230V, 3~50/60 Hz
Mains cable cross-section 4x1,5 mm
2
4x2,5 mm
2
Mains fuse 10 A delayed 20 A delayed
Rated power consumption 9,7 kVA
Rated primary current P30% 12A 21 A
Rated welding current Duty cycle* 30% 220 A
Duty cycle* 60% 155A
Duty cycle* 100% 120 A
Welding current range
20÷220 A
Open circuit voltage 14-32 V
Enclosure class IP 23
Application class
Dimensions Length
Width
Height
770
520
620
Weight 90 kg
*Duty cycle is based on 10-minute period. Duty cycle 30% means that after 3 minutes of unit operation,
7 minutes brake is required. Duty cycle 100% means that the unit can work continuously.
Warning:
The unit is characterised by the following:
- Enclosure class IP 23 indicates that the unit is designed for indoor and outdoor use.
- Application class S means that the unit is designed for use in areas of elevated electric hazard.
5. LOAD CHARACTERISTIC
0
5
10
15
20
25
30
35
40
0 20 40 60 80 100 120 140 160 180 200 220
I2(A)
U2(V)
S
17
6. INSTALLATION
A competent and authorised person must install the equipment.
Connect the mains cable, and protect it with the appropriate fuses, in accordance with regulations.
Make sure that the power unit is not covered or installed such that cooling is impeded.
PRIMARY CURRENT, MAINS FUSE AND MAINS CABLE
Voltage 400-415V
3~ 50 Hz
230V
3~ 50 Hz
Primary current at:
100% duty cycle 5A 8,6A
60% duty cycle 7A 12A
30% duty cycle 12A 21A
Conductor
4x1,5mm² 4x2,5mm²
Fuse, slow-blow
10A 20A
7. INSTRUCTION FOR USE
The LKB 220S is step-switched welding power unit, intended for welding with solid filler wires of steel,
stainless steel or aluminium, and cored wires with or without shielding gas.
The power units can be fitted with an instrument for display of current and voltage. It incorporates a sample-
and-hold function.
A thermal overload cutout protects against overheating. The cutout resets automatically when the unit has
cooled.
CONTROL PANEL
Fig. 7.1 Front view of the LKB220S
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A. POWER SWITCH - Turning this switch to the ‘I’ position applies power to the unit. The green LED diode
(pos. B) will illuminate indicating that power is supplied to equipment. Cooling fan will also be switched
on.
B. OVERHEATING. The orange LED diode will illuminate in the event of overheating. The welding output is
then automatically disabled until the LKB reaches normal temperature. While this indicator illuminate
leave the power source for a few minutes to cool down. Do not switch the power source off, as this will
remove the power from the cooling fan. The unit will be ready to resume welding when the orange
indicator has changed to green.
C. INDICATOR of the synergy control status:
- red light when operation prohibited (control function disabled),
- green light continuous – correct parameters for work,
- green light flashing - possible operation in synergy mode – but not recommended (“mixed” arc).
D. WELDING VOLTAGE ADJUSTMENT is carried out by means of a coarse control 3 position switch, and
a fine control 7 position switch It is therefore possible to select 21 different welding voltage outputs.
WARNINR: Operating these voltage switches during welding process (loaded power source) can
cause damage to unit!
E. DIGITAL INSTRUMENT displays welding parameter – corresponding to value of welding voltage –
pre-set by the switches D. These parameters are determined by the microprocessor – depending on the
selected value of welding voltage. Parameters to be displayed – are selected by the toggle switches in
the front of the instrument:
- Upper display block shows welding voltage or current, (before start of welding – prospective values,
during welding – actual values- and after stop of welding – dimmed display shows memorised last value
of the current or voltage – i.e. HOLD – FUNCTION is active),
- Lower display – block shows recommended thickness of material to be welded – or reference value of
the wire speed (depending on the selectors D).
F. POTENTIOMETER with switch – to switch on spot welding mode and impulse time (for spot welding) in
the range of 0,5 ÷ 4 s.
G. POTENTIOMETER to set wire feeding speed: for “synergy” control – in the range of ±10% value of the
speed - pre-set by the program; for “standard” control – in full range of 1,4÷19 m/min.
H. INDICATORS ( 2 x LED) for proper selection of the output current socket.
I. OUTPUT SOCKETS to connect work return cable with clamp
J. CONNECTION (Euro connection) to connect welding torch
Fig.7.2 View of the control panel in the wire feeder compartment for LKB220S
K. CONTROL MODE SELECTOR - “standard” – (i.e. SYNERGY OFF) or „Synergy” control; for “synergy” –
allows to select data of the filler wire material and shield gas.
L. POTENTIOMETER for presetting of the filler wire diameter
M. POTENTIOMETER of burnback time regulation.
19
N. MODE SELECTOR 2-stroke – motor test – 4-stroke
8. MAINTENANCE
Regular maintenance is important for reliable, safe operation.
• Blow the power until clean with dry compressed air at reduced pressure.
• For problem-free wire feed, clean and replace the wearing parts in the wire feed mechanism at regular
intervals.
Note that an excessive pressure setting can cause abnormal wear on the drive roller, feed roller and wire
conduit.
• Blow the wire conduit clean at regular intervals and clean the gas nozzle.
WARNING! If periodical HV tests are to be carried out according to local safety regulations
(in some countries obligatory!), the following circuits must be isolated during the test, by
means of disconnecting the connectors:
X1(A1), X5(A1), X6:1-4(A1), X6:5-8(A1), X9:1-2(A1), X10(A1)
9. ACCESSORIES
9.1 TRANSFORMER SET FOR CO
2
–HEATER (0349 302 080)
ASSEMBLY INSTRUCTION
1. Take off side panels of unit.
2. Install transformer T3 and terminal block XG in places marked with arrows.
3. Connect wiring of transformer T3 to components according to schematic diagram of unit.
1- Transformer T2
2- Transformer T3
3- Terminal block XG
4- Wiring for Q1 and T2
20
10. SPARE PARTS LIST
Item no.
Qty
LKB 220S
400-415V
Qty
LKB 220S
3x230V
Ordering no. Denomination Notes
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
1
1
1
1
-
1
-
1
1
1
1
2
4
1
1
2
2
2
2
1
1
1
1
1
1
2
1
1
1
-
1
-
1
1
1
1
1
2
4
1
1
2
2
2
2
1
1
1
1
1
1
2
0349 302 103
0349 302 116
0349 302 157
0349 302 114
0349 302 185
0349 302 115
0349 302 184
0349 302 094
0349 302 095
0349 302 092
0349 302 093
0349 302 091
0457 290 003
0455 172 001
0455 174 001
0455 457 001
0455 467 001
0160 362 881
0457 290 004
0349 302 112
0458 004 001
0456 031 004
0456 031 002
0469 516 003
0349 302 180
0192 859 126
Front panel
Panel
Rotary cam switch
Rotary cam switch
Rotary cam switch
Rotary cam switch
Rotary cam switch
Potentiometer
Potentiometer
Knob
Knob
LED (green/red)
LED-holder (socket)
Protection glass
Seal
Wheel
Castor wheel
Current connector-socket
LED (green)
Circuit board QSyn-Meter20
Cover lid
Side plate
Side plate
Shaft
Clamp
Locking washer
Q1
Q2
Q2
Q3
Q3
RP1
RP2
H1/H2, H3/H4
H5, H6
A2
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ESAB LKB 220S is a versatile welding machine capable of handling a wide range of welding applications. It features precise wire feed speed control for consistent welds and a "creep speed" function for starting welds with reduced spatter. The LKB 220S also includes a built-in spot welding function with adjustable timing for precise welds. With its user-friendly controls and rugged construction, this machine is well-suited for professional welding tasks.
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