ESAB LTN 160 User manual

0740 800 061

Valid for serial no. 313--xxx--xxxx to 011--xxx--xxxx040823

LTN 160/200

Aristotig 160/200

Service manual

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LIST OF CONTENTS Page

READ THIS FIRST 5................................................................

COMPONENT DESCRIPTION, LTN 160/200 6.........................................

WIRING DIAGRAM 8................................................................

LTN 160 Valid for ser.no. 313--xxx--xxxx to ser.no. 508--xxx--xxxx 9......................

LTN 160 Valid from ser.no. 540--xxx--xxxx 10..........................................

LTN 200 Valid for ser.no. 313--xxx--xxxx to ser.no. 508--xxx--xxxx 11......................

LTN 200 Valid from ser.no. 540--xxx--xxxx 12..........................................

T ransient protection, rectifier unit V03, V04 13.........................................

BLOCK DIAGRAM 14................................................................

CIRCUIT BOARD AP01 16............................................................

1 Power supply 16................................................................

2 Power supply monitoring 17......................................................

3 Start / Stop input 18.............................................................

4 Remote control input 18.........................................................

5 Shunt input with amplifier AP10 19................................................

6 Arc voltage monitoring 20........................................................

7 HF generator 20................................................................

8 Gas valve 21...................................................................

9 Machine type indicator 21........................................................

10 Thermal overload cutout 21......................................................

11 Welding process control 22.......................................................

Hot start MMA 22...............................................................

12 Control panel interface circuits 23.................................................

13 Pulse width modulator 24........................................................

14 Gate circuit 24..................................................................

Checking the gate pulses 25.....................................................

Component positions, circuit board AP01 26...........................................

TRANSISTOR BOARD AP02 28......................................................

TRANSISTOR BOARD AP03 30......................................................

MOS TESTER 32....................................................................

SOFT STARTING 33.................................................................

CONTROL PANEL AP05 34..........................................................

DISPLAY BOARD AP06 36...........................................................

SUPPRESSION CIRCUIT BOARD AP07 37............................................

SUPPRESSION CIRCUIT BOARD AP08 38............................................

LTN 160/200 with ser.no. 313--, 405--, 440--, and 508--xxx--xxxx 38.......................

LTN 160 with ser.no. 540-- and 628--xxx--xxxx 38......................................

LTN 200 with ser.no. 540-- and 628--xxx--xxxx 38......................................

SUPPRESSION BOARD AP09 40.....................................................

F AULT CODES 41...................................................................

DISASSEMBLY / REASSEMBLY 43....................................................

Rectifier unit (V03, V04) 43..........................................................

Assembling the diode modules 43....................................................

Removal of transistor circuit boards AP02 and AP03 44.................................

Refitting the transistor circuit board 44................................................

Fitting the main transformer TC02 45.................................................

LOAD CHARACTERISTICS 46........................................................

TECHNICAL DATA 47................................................................

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INSTRUCTIONS 48..................................................................

INTRODUCTION 48.................................................................

INTSTALLATION 48.................................................................

OPERATION 49.....................................................................

Control panel 50...................................................................

MAINTENANCE 54..................................................................

SPARE PARTS 54...................................................................

NOTES 55..........................................................................

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 block 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 wiri ng diagram are listed in the

component description.

This manual contains details of all design changes that have been made up to and including

August 2004.

This manual is valid for LTN 160 and LTN 200 with serial numbers:

313--xxx--xxx, 405--xxx--xxxx, 440--xxx--xxxx, 508--xxx--xxxx, 540--xxx--xxxx,

628--xxx--xxxx, 011--xxx--xxxx

The LTN 160 and LTN 200 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 standards.

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 stance 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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COMPONENT DESCRIPTION, LTN 160/200

This component description refers to the wiring diagrams.

The LTN 160 and the LTN 200 are primary--switched power units, using parallel--connected

MOSFET--transistors as the switching elements. The switching frequency is 36.5 kHz. The

conducting interval varies between zero and 11 µs, depending on the welding current output.

The conducting time and frequency are controlled by circuit board AP01.

WARNING !

STATIC ELECTRICITY can damage circuit

boards and electronic components.

S Observe precautions for handling electrostatic

sensitive devices.

S Use proper static--proof bags and boxes.

ESD

AP01 The main circuit board with control electronics.

See block diagram on page 14 and description on page 16.

AP02 Circuit board with power transistors for the positive pole,

see description on page 28.

WARNING! the transistors are connected to mains voltage potential.

AP03 Circuit board with power transistors for the negative pole,

see description on page 30.

WARNING! the transistors are connected to mains voltage potential.

AP04 Interference suppression circuit board, transient protection, protecting the

secondary diodes against transients.

Replaced by capacitors C10 from serial number 628--xxx--xxxx see:

Transient protection, rectifier unit V03, V04 on page 13.

AP05 Circuit board control panel. The circuit diagram is shown on page 34.

AP06 Display driver board with pulse generator. The circuit diagram is shown on

page 36.

AP07 Interference suppression circuit board: see the circuit diagram on page 37.

AP08 Interference suppression circuit board: see the circuit diagram on page 38.

AP09 Interference suppression circuit board, remote control connector, see the

diagram on page 40.

AP10 Circuit board shunt amplifier, see description on page 19.

AP11 HF generator.

C01 Capacitor, 0.1µF, 1000 VDC, transient protection.

C02 Capacitor, 1000µF, buffer/smoothing capacitor. Time to discharge after

turning off the unit: about two minutes.

C03 See C02. This capacitor is only fitted in LTN 200.

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C04 Decoupling capacitor, 0.1µF, 1000 VDC, protects against HF.

C05 2 -- capacitors, 4.7µF, see L02.

C06 -- C09 Capacitor, 0.1µF, 400 VDC

C10 2 -- capacitors, 12 nF. Protection against transient voltages.

Replacing AP04 from serial number 628--xxx--xxxx. From serial number

011--xxx--xxxx the capacitors are replaced by L04 and L05 see:

Transient protection, rectifier unit V03, V04 on page 13.

EV01 Fan, 24 VDC

HL01 Lamp, 28 V, white, lights when mains power is on.

L01 Secondary inductor.

L02 Inductor, forms an LC circuit with C05 and V06 to reduce the risk of arc

extinction at low welding currents.

When V03 conducts, the LC circuit charges up. The circuit is capable of

temporarily maintaining a high arc voltage at low current, thus reducing the

risk of arc extinction.

Diode V06 prevents capacitor C05 from going negative.

L03 Primary inductor, improves the machine’s form factor, i.e. reduces the mains

load. Inductor L03 is only mounted in LTN 160.

L04, L05 Ferrite ring cor es, transient voltage protection.

Replaces C10 from serial number 011--xxx--xxxx.

QF01 Mains power supply switch, 2--pole in the LTN 160 and

3--pole in the LTN 200.

R01 Resistor, 3.9 kΩ 5W.

RS01 Shunt, 120 mV at 140 A (LTN 160) or 200 A (LTN 200).

ST01 Thermal overload cutout, for overload protection, mounted on the m ain

transformer (TC02) winding.

LTN 160: breaks at 130 _C and resets at 100 _C.

LTN 200: breaks at 150 _C and resets at 130 _C.

TC01 Control power transformer. The primary is supplied at 230 V (LTN 160) or

400 V (LTN 200), with secondary output voltages of 9, 20, 26 and 42 V.

Machines produced after week 719 have fuses fitted on the control trans-

former.

TC02 Main transformer. For fitting instructions, see page 45.

TV01 HF transformer.

V01, V02 After r eplacing the rectifier bridges, the machine must be soft--started: see

instructions on page 33.

Rectifier bridge V02 is only mounted in the LT N 200.

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V03, V04 Rectifier and freewheel diodes.

V03 r ectifies the welding current.

During the time interval between two voltage pulses from transformer

TC02, the freewheel diodes V04 maintain the welding current from inductor

L01.

Before serial number 628--xxx--xxxx:

V03 consists of six parallel--connected diodes, and V04 consists of eight

parallel--connected diodes. V03 and V04 are mounted on the same cooling

fins. If any of the diodes is/are faulty, the entire cooling f in unit must be

replaced, as the diodes are soldered to it.

For spare parts see the spare parts list item 430.

From serial number 628--xxx--xxxx:

A new r ectifier unit is introduced. On the cooling fins in the LTN 160 is one

diode module mounted and in the LTN 200 are two diode modules mounted.

Each diode module consists of two diodes.

For installation instructions, see page 43.

V05 LED, yellow. Lights when thermal cutout ST01 operates (breaks) as a

result of high temperature.

V06 Diode, see L02.

X01 -- X02 Terminal block.

XS . . Sleeve connectors.

XS04 26--pole ribbon cable connector.

XS10 12--pole Burndy contact, for connection of remote control unit.

XS11 TIG centr al connector: only LTN models --880 and --882.

XS12 2--pole Cannon connector, only LTN models --881, --883 and --884.

XS13 Welding current connector, OKC, only LTN models --881, --883 and --884.

XS14 Welding current terminals, (two), OKC type.

XS20 26--pole connector for ribbon cable.

YV01 Solenoid valve.

WIRING DIAGRAM

The wiring diagrams for the LTN 160 and 200, on pages 10 and 12 are valid from serial

number 540--xxx--xxxx. For serial no. 628--xxx--xxxx and 011 --xxx--xxxx changes are made

to the rectifier unit, which affects the wiring diagrams. The changes i n the diagrams are

shown on page 13.

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LTN 160 Valid for ser.no. 313--xxx--xxxx to ser.no. 508--xxx--xxxx

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LTN 160 Valid from ser.no. 540--xxx--xxxx

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LTN 200 Valid for ser.no. 313--xxx--xxxx to ser.no. 508--xxx--xxxx

AP11

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LTN 200 Valid from ser.no. 540--xxx--xxxx

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Transient protection, rectifier unit V03, V04

C10

LTN 160 LTN 200

Before serial number 628--xxx--xxxx, circuit board

AP04 protects against transient voltages.

LTN 160/200

with serial number 628--xxx--xxxx.

The two capacitors C10 protects against

transient voltages.

LTN 160/200

with serial number 011--xxx--xxxx.

The two ferrite ring cores L04 and L05

protects against transient voltages.

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BLOCK DIAGRAM

1 Power supply

2 Power supply monitoring

3 Start / Stop input

4 Remote control input

5 Shunt input with amplifier

6 Arc voltage sensing

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7 HF unit

8 Gas valve

9 Machine type selection

10 Thermal overload switch

11 Welding process control

12 Interface circuits for control panel

13 Pulse width modulator

14 Gate circuit

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CIRCUIT BOARD AP01

This description refers to the block diagram on page 14 and to the components position

diagram on page 26.

Only those parts connected to the boar d ’s inputs and outputs are described here. If the circuit

board is faulty, it must be replaced.

After replacing the circuit board, the machine must be soft--started. See the instructions

on page 33.

1 Power supply

The power supply to the board can be divided into three parts; a, b and c.

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The supply voltage from transformer TC01 is rectified and voltage regulator VR2

stabilises the supply to +5 ¦0.25V DC.

Resistors R126 and R127, capacitor C104 and diode D27 form a voltage monitoring

circuit for the unregulated supply to voltage regulator VR2.

The voltage from potential divider R126/R127 is connected to pin 9 of IC7: see 2)

below. The voltage is about 2. 5V.

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Voltage regulator VR4 supplies the fan E V01 with +28V.

Voltage regulator VR3 produces a stabilised +15V supply, which is used to supply

the remote control unit. This supply is ref erred to as +15VB, and its neutral point,

0VB, is separated from the electronic neutral (0V). Potentiometer R122 is used to

adjust the voltage. See also 4) on page 18.

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Voltage regulator VR1 produces an output voltage of +20 ¦1.0V, which supplies the

pulse width modulator output stage (Block 13).

Potential divider R100/R101 supplies 2.6V to the processor in Block 11. This

provides a signal that the power supply is available.

The +27V unregulated DC power supply to VR1 also supplies relay RE1 in Block 7

and indicating lamp HL01 via resistor R120.

Zener diode D22 drops the voltage to +15V, and this, together with the --15V supply,

powers t he analogue circuits. The processor monitors the --15V supply by a signal

from resistor R54.

2 Power supply monitoring

IC7 and IC9 monitor the voltage of battery

BA1. The nominal battery voltage is 3V. If

it falls below 2.5V, the display shows error

message E06. Battery life is about five

years.

The machine also operates without battery,

but data stored in the welding data memory,

see page 53, disappears when the mains

voltage is switched off. At power up default

values will be read into the memory.

A voltage of about 2.5V is supplied to IC7, pin 9, from power supply circuit 1a.

If this voltage drops below the threshold voltage of 1.3V, pin 10 of IC7 goes low,

providing the processor with a low power supply voltage signal. The processor then

generates a ” ” warning signal in the display and stores current data.

If the +5V supply to pin 3 of IC7 drops below 4. 65V, pin 15 goes low and inhibits

the pulse width modulator in block 13. The processor receives a reset signal and

data in the RAM memory is protected by the backup battery power supply.

Pin 2 of IC7 supplies the RAM memory in Block 11 with power, both when the

machine is energised and when it is shut down.

When power to the machine is turned off, the display also shows ” ”to

confirm that the processor has stored the current data.

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3 Start / Stop input

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The output signal from IC14, pin 4, goes high (+5V) when the torch contact switch

is not activated, and low (0V) when it is activated.

4 Remote control input

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If the remote control input is activated, but there is no reference signal, resistor R72

holds the reference input low. This results in a welding current of 3A f or TI G

welding and 4A for MMA welding.

The remote control unit plug must incorporate a link between pins L and M. When

the remote control unit is connected, the voltage at the cathode of diode D19 is 0V.

With the remote control unit removed, the voltage at the cathode of the diode is +5V.

When adjusting the +15VB voltage, link connections C3 and C4 and measure the

voltage at the cathode of diode D12. The voltage there must be 5.1 ¦0.05V. Adjust

the voltage by means of resistor R122: see circuit diagram 1b on page 16.

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5 Shunt input with amplifier AP10

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Shunt amplifier circuit board AP10 is supplied with ¦15V f rom circuit board AP01.

At no--load voltage, the circuit board’s neutral voltage (0V) is at the same potential

as the welding circuit negative connection.

In the LTN 160, 120 mV shunt voltage corr esponds to 140 A welding current. In the

LTN 200, 120 mV shunt voltage corresponds to 200 A welding current. In order to

be able to use the same programs in both machines, a simple resistor network

interface circuit (see 9) on page 21 tells the processor which type the machine is.

In the 200 machine, the signal from t he shunt is amplified by the shunt amplifier, so

that a 120 mV input signal from t he shunt produces a 6.66 V output signal. Resistors

R10, R6 and R7 on circuit board AP01 divide this voltage to 2.12 V, which is then

suppliedtopin3ofIC2.

In the 160 machine, transistor Q1 is turned on by IC8. This connects resistor R9 to

0V, connecting resistors R8 and R9 in parallel with R6 and R7. With R10, these

resistors f orm a potential divider which divides the 6.66 V to 1. 48 V, which is then

suppliedtopin3ofIC2.

IC2 is a buffer circuit. The processor receives a signal representing the welding

current from output pin 6 of IC2 via filter R20 and C17. Resistor R4 connects the

shunt signal to the control amplifier.

The LTN 160/200 has different current setting resolutions in the TIG and MMA

modes. In the T IG mode, the welding current can be set in 1A steps, while in the

MMA mode, the current can be set in 2A steps. This means that the lowest current

in the MMA mode is 4A, while in the TIG mode it is 3A.

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Component positions, AP10

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6 Arc voltage monitoring

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This circuit measures and scales the arc voltage to a suitable level for the processor.

64V arc voltage produces a voltage signal of 5.1V at the cathode of diode D3.

Open--circuit volt age control

The arc voltage is connected to input D2 and supplied to potential divider R29 and

R30, the output from which is supplied to the voltage control circuit. The

open--circuit voltage must be about 70V.

7 HF generator

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WARNING: Dangerous voltages in this circuit.

When the welding torch switch is operated, and the open--circuit arc voltage is over

50V, relay RE1 closes and turns on HF generator AP11. It remains activated for

0.75 seconds. If the arc has not struck within this time, the relay drops off.

The voltage on the primary side of HF transformer TV01 is about 400 V, and the

secondary voltage is about 8 kV.

a. Filter RC1 is not fitted to machines with serial numbers of 313--351--xxxx and

above. Where the filter is fitted (i.e. to earlier machines), it can happen that the

welding torch produces weak HF sparks even when the torch trigger switch

contact is not activated. This is not dangerous to the operator, but the f ilter

should be removed when the machine is next being serviced.

From serial number xxx--006--xxxx a new type of HF generator is used,

0367 268 001. This generator produces about 500 V on the primary side of the HF

transformer and about 10 kV on the secondary side.

The new HF generator replaces the old type as spare part for older machines. The

colour of the new type is grey, the old is black. The new has screw connections for

the connection cables and different hole pattern for the mounting.

When fitting the new generator to older machines: three new mounting holes for the

generator must be drilled and the cable shoes must be removed from the connection

cables. Fit the generator with the connection terminal turned towards the base plate.

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