ESAB MEH 44 Basic User manual

Brand: ESAB

Model: MEH 44 Basic

Category: Welding System

Type: User manual

This manual is also suitable for

MEH 30

ESAB MEH 44 Basic is a reliable wire feed unit for MIG/MAG welding that offers precise wire feeding and voltage control for professional welding results. With its durable construction and user-friendly interface, the MEH 44 Basic is suitable for various welding applications in workshops and industrial environments.

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0740 800 079

Valid for machine no. 025--xxx--xxxx to 626--xxx--xxxx020704

MEH 30 Basic

MEH 44 Basic

Service manual

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LIST OF CONTENTS Page

READ THIS FIRST 3...............................................................

INTRODUCTION 4.................................................................

TECHNICAL DESCRIPTION, MEH 30B 6.............................................

WIRING DIAGRAM, MEH 30B 7.....................................................

TECHNICAL DESCRIPTION, MEH 44B 8.............................................

WIRING DIAGRAM, MEH 44B 9.....................................................

DESCRIPTION OF CIRCUIT BOARD AP01 10.........................................

CIRCUIT DIAGRAM, CIRCUIT BOARD AP01 12........................................

COMPONENT POSITIONS, CIRCUIT BOARD AP01 14.................................

F AULT TRACING 16................................................................

INTERFACE UNIT, TYPE PKE 0467 820 880 17........................................

VOLTAGE CONTROL POTENTIOMETER 0467 650 880 18..............................

INSTRUCTION MANUAL 21.........................................................

SAFETY 21........................................................................

TECHNICAL DATA 22...............................................................

INSTALLATION 23..................................................................

MAINTENANCE 23.................................................................

SPARE PARTS LIST 25..............................................................

ACCESSORIES 34..................................................................

NOTES 37.........................................................................

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.

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

including June 2002.

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INTRODUCTION

The MEH 30 and the MEH 44 are two wire feed units for MIG/MAG welding from the A10

range, using ESAB’s A10 system for feeding the wire.

Both units are built up in the same way and, apart from their lengths, have the same

physical dimensions.

The MEH 44 is longer in order to provide space for a larger feeder unit and for a 44 cm

diameter wire bobbin. The MEH 30 will accept wire bobbins of up to 30 cm diameter. It is

these sizes that give the numbers in the units’ type designations.

The letter E in the type designation indicates that the motors are controlled e lectronically.

The system is th e same for both u nits.

The letter M in the type designation indicates a feeder unit, and H is the generation letter.

Both units have changeover switches for 2/4-- stroke welding (SW1) and for normal or creep

start (SW2), while the MEH 44 also has a switch for reversing the motors in order to

facilitate removal of thicker wires from the welding hose. The switches are fitted in the panel

behind the cover. A connection for a remote control unit is provided on the front panel:

simply fitting the cable brings the remote control unit into operation immediately.

To provide a complete, practical working unit requires either a swivel mount, a

counterbalanced support or a trolley. The feeder can be fitted to an insulated post on the

power unit using either the swivel mount or the counterbalance unit. Alternatively, fitting the

unit on the trolley provides mobility in the workshop or on a workbench.

Units on swivel mounts or trolleys can also be fitted with a counterbalanced support to allow

them to be hung above the working position.

A general technical description, together with installation instructions, can be found in the

instructions.

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Connectors and control devices on the front of the feeder unit

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Internal controls. Note that the MEH 30 has no reversing action

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TECHNICAL DESCRIPTION, MEH 30B

Contact XP01 (plug) provides the power supply and signal connection between the power

unit and the feed unit.

S Pins A and B carry the 42V power supply.

S Pin F is the control connection for the contactor in the power unit.

S Pins R and S are the tachometer connections to the power unit. This signal is used if

the power unit incorporates a wire feed speed display.

S Pins J and L carry a reference voltage signal from the power unit to two potentiometers:

one for welding voltage control (RP02, optional), and one for the voltage control

potentiometer on the remote control unit. See a lso the circuit diagram on page 13.

S Pin K carries the voltage reference signal to the power unit.

RP01, is a potentiometer (2.5kτ 2W), fitted to the front of the unit, for controlling the wire

feed speed.

Optional potentiometer RP02 (2.5kτ 2W), fitted to the front panel, controls the welding

voltage.

SA1 is a changeover switch for selecting control of welding voltage from either RP02 or

from the remote control unit. (Control from RP02 is an optional feature.) Before either the

remote control unit potentiometer or RP02 can be used to control the welding voltage, it is

necessary to change over connections in the power unit in order to disengage its

potentiometer.

M01 is a 24V motor built together with tachogenerator G01.

C01 is a 0.1←F 125V AC capacitor.

Resistors R01, R02 and R03 limit the motor starting current. (R01 = 0.3τ 50W, R02 = 0.5τ

50W, R03 = 0.75τ 50W.)

Resistor R01 and diode V01 (MR 754) limit the motor braking current.

From serial no. 127-- xxx--xxxx the current limit function is integrated in the circuit board.

This gives as a result, that the old version of circuit board (part no. 0481 703 882) can not

be used as a spare part in the new versions of MEH.

When using a new circuit board (part no. 0481 911 882) as a spare part in an old wire

feeder, the components R01, R02, R03 and V01 should be removed and wire 027 has to be

connected to wire 018.

The current relay provides a signal to the circuit board when welding current is flowing. If

the creep start mode has been selected, wire feed speed will be increased from creep

speed to the set speed when the current relay operates. The relay is mounted adjacent to

the welding current cable terminal.

XS01 (the 12 pole socket connector) is the connector for the remote control unit. Sockets A,

B and C are for the wire feed speed control circuit, while sockets F, G and H are in the

welding voltage control circuit.

YV1 is the solenoid valve for shielding gas control.

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WIRING DIAGRAM, MEH 30B

* The blue wire is connected to B4 and the red to B5 when the power source is equipped with

an intrument that shows the wire feed speed.

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TECHNICAL DESCRIPTION, MEH 44B

Contact XP01 (plug) provides the power supply and signal connection between the power

unit and the feed unit.

S Pins A and B carry the 42V power supply.

S Pin F is the control connection for the contactor in the power unit.

S Pins R and S are the tachometer connections to the power unit. This signal is used if

the power unit incorporates a wire feed speed display.

S Pins J and L carry a reference voltage signal from the power unit to two potentiometers:

one for welding voltage control (RP02, optional), and one for the voltage control

potentiometer on the remote control unit. See a lso the circuit diagram on page 13.

S Pin K carries the voltage reference signal to the power unit.

RP01, is a potentiometer (2.5kτ 2W), fitted to the front of the unit, for controlling the wire

feed speed.

Optional potentiometer RP02 (2.5kτ 2W), fitted to the front panel, controls the welding

voltage.

SA1 is a changeover switch for selecting control of welding voltage from either RP02 or

from the remote control unit. (Control from RP02 is an optional feature.)

Before either the remote control unit potentiometer or RP02 can be used to control the

welding voltage, it is necessary to change over connections in the power unit in order to

disengage its potentiometer.

M01 and M02 are two 12V motors connected in series. M01 is built together with

tachogenerator G01.

C01 is a 0.1←F 125V AC capacitor. Resistors R01, R02and R03limit the motor starting

current. (R01 = 0.3τ 50W, R02 = 0.5τ 50W, R03 = 0.75τ 50W.)

Resistor R01 and diode V01(MR 754) limit the motor braking current.

From serial no. 127-- xxx--xxxx the current limit function is integrated in the circuit board.

This gives as a result, that the old version of circuit board (part no. 0481 703 880) can not

be used as a spare part in the new versions of MEH.

When using a new circuit board (part no. 0481 911 880) as a spare part in an old wire

feeder, the components R01, R02, R03 and V01 should be removed and wire 027 has to be

connected to wire 018.

The current relay provides a signal to the circuit board when welding current is flowing.

If the creep start mode has been selected, wire feed speed will be increased from creep

speed to the set speed when the current relay operates. The relay is mounted adjacent to

the welding current cable terminal.

XS01 (the 12 pole socket connector) is the connector for the remote control unit. Sockets A,

B and C are for the wire feed speed control circuit, while sockets F, G and H are in the

welding voltage control circuit.

YV1 is the solenoid valve for shielding gas control.

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WIRING DIAGRAM, MEH 44B

* The blue wire is connected to B4 and the red to B5 when the power source is equipped with

an intrument that shows the wire feed speed.

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DESCRIPTION OF CIRCUIT BOARD AP01

This description refers to the circuit diagram on page 12 and on page 13.

1 Power supply

The circuit board is supplied, via screw terminals B1 and B2, with 42V AC, which is fed to

transformer TR1. Terminals 11 and 12 on the transformer supply 14V AC to rectifier bridge

BR1, the output voltage of which is regulated to +15V by VR1 and to +5V by VR2.

Rectifier bridge BR2 is also supplied with 14V AC, from terminals 7 and 8 on TR1.

The rectified voltage is regulated to 13V by zener diode D9. The 13V and the 0V lines are

separated from other power supply voltages on the board, and used to drive the control

circuits for transistor Q1.

2 Start / Stop

The welding torch contact is supplied with 19V AC from terminal 9 on TR1 via pin A1.

Pin A2, which is connected to the welding current cable, completes the circuit from the torch

trigger switch. Optocoupler IC1 provides galvanic insulation from the welding circuit.

3 Tachometer

The tachometer signal (800 Hz at 25 m/min wire feed speed) is received via contact pins A5

and A6. Screw terminals B4 and B5 provide a parallel signal path to the power unit, where it

is used if the power unit incorporates a wire feed speed display. Comparator IC2 converts

the tachometer signal to a 4.8V square wave.

4 Wire feed speed

Pin contact E1 provides the feed unit with a wire feed speed reference signal when the unit

is being used with a robot or other external equipment.

Potentiometer RP01 (wire feed speed control) on the front of the feeder unit is connected to

pins E2, E3 and E4.

5 Burn--back time

Potentiometer R5 on the circuit board allows the post--burn time to be adjusted between 0

and 0.5 seconds. The potentiometer is accessible inside the cover on the feed unit, as

shown in the picture on page 5.

6 Remote wire feed speed

The wire feed speed potentiometer in the remote control unit is connected to contact pins

A9, A10 and A11 on the circuit board via connector XS01. Fitting the remote control to the

feed unit automatically disengages control of the wire feed speed from the potentiometer on

the front panel of the unit, and transfers it to the potentiometer on the remote control unit.

7 Current relay

Pin A3 is taken low by the current relay when the relay operates. If the creep start mode

has been selected, wire feed speed increases from creep speed to the set value when the

relay operates.

8 2/4 -- Stroke, Creep start, Reversed wire feed

Switches SW1, SW2 and SW3 are fitted inside the panel on the feeder unit, as shown in the

picture on page 5.

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2/4 -- Stroke

Switch SW1 selects two--stroke or four--stroke control mode.

Two--stroke control mode means that gas flow and wire feed start, and the welding current

contactor in the power unit closes, when the trigger switch on the welding torch is operated.

When the trigger switch is released, wire feed and gas flow stop, and the contactor is

released after expiry of the preset post--burn time (0 -- 0.5 seconds).

Four--stroke welding control means that gas supply starts when the welding torch trigger

switch is pressed for the first time.

Releasing the trigger switch then starts wire feed and closes the welding current contactor.

Pressing the switch for a second time stops the wire feed, with the welding current contactor

opening after the preset post--burn time has expired.

Finally, releasing the trigger switch stops the gas post--flow.

Creep start

Switch SW2 selects creep start or normal start. Creep speed is 50% of the set speed.

Reversed wire feed

Switch SW3 is a spring--return switch to control reverse wire feed. It is fitted only to the MEH

44. Transistor Q3 and relay RE1 are fitted only to the MEH 44. In the MEH 30, they are

replaced by links BY2 and BY3.

9 Voltage adjustment

Terminals B6 and B8 are +15V and 0V connections from the power unit, supplying

potentiometer RP02 or the welding voltage control potentiometer on the remote control unit.

Terminal B7 carries the voltage signal from the potentiometer (whichever one is in use) to

the power unit.

Selection of welding voltage control from either the remote control unit or RP02 requires

manual reconnection in the power unit to disengage the power unit’s voltage control

potentiometer. RP02 is an optional extra item, which is fitted to the front of the feeder unit

together with selector switch SA1, which controls choice of either RP02 or the remote

control unit.

10 Activation, cont acto r

The welding current contactor in the power unit is supplied via optotriac TRC2 and screw

terminal B3. TRC2 is continuously rated at 3A.

11 Gas valve

Solenoid valve YV1 is supplied at 42V AC via contacts A7 and A8 and optotriac TRC1.

TRC1 is continuously rated at 1A.

12 Motor driving / braking

Connector pins H1 and H2 supply the feeder unit drive motors. The MEH 44 unit has two

series --connected 12V motors, while the MEH 30 has a single 24V motor. Motor speeds are

controlled by pulse --width modulation (PWM), operating at 15,6 kHz with a maximum

duty--cycle of 86%. The brake circuit is also PWM--controlled at 15,6 kHz, with a constant

duty--cycle of 92%.

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CIRCUIT DIAGRAM, CIRCUIT BOARD AP01

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COMPONENT POSITIONS, CIRCUIT BOARD AP01

481 703-- 880/882

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COMPONENT POSITIONS, CIRCUIT BOARD AP01

481 911--880/882

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FAULT TRACING

The processor on the circuit board incorporates an inbuilt speed monitoring function.

If the feeder motor speed deviates from the set speed by more than 1.0 m/minute for more

than 1.3 seconds, the motor will be stopped.

The motor can be restarted. If whatever caused the change of speed has been corrected,

or is no longer present, wire feed will continue. If the fault etc. is still present, the motor will

stop again a fter 1.3 seconds.

Possible reasons for activation of the speed monitor are:

S MEH 44B: The feed unit motors are being run at high speed without wire. For the

motors to run smoothly, they need to be mechanically coupled by the presence of the

wire between the drive rollers.

S The motor(s) is/are slipping because the wire has welded fast to the contact tip.

S There is a break in the tachometer circuit.

The pre series of MEH Basic are not equipped with the speed monitor function.

The PROM in those machines is marked MEH BASIC.

PROM’s with the speed monitor function are marked with the program edition number

(e.g. M2.3).

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INTERFACE UNIT, TYPE PKE 0467 820 880

OPTIONAL EQUIPMENT

Fitting instructions

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VOLTAGE CONTROL POTENTIOMETER 0467 650 880

OPTIONAL EQUIPMENT

Fitting instructions

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ESAB MEH 44 Basic User manual

Brand: ESAB

Model: MEH 44 Basic

Category: Welding System

Type: User manual

This manual is also suitable for

MEH 30

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ESAB MEH 44 Basic User manual

This manual is also suitable for

ESAB MEH 44 Basic User manual

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