ESAB cmek2de1 User Manual

MEK 2

Service manual

0740 800 094

020531

LIST OF CONTENTS Page

READ THIS FIRST 2..................................

COMPONENT DESCRIPTION 4........................

CONNECTION DIAGRAM 5............................

DESCRIPTION OF OPERATION 6......................

1 Power supply 7.........................................

2 2--stroke / 4--stroke 8....................................

3 Start / Stop 8...........................................

4 Current relay, Creep start / Normal start 9..................

5 Motor driving / braking 10..................................

6 Tachometer input 1 1......................................

7 Burn--back time 1 1.......................................

8 Wire feed speed 1 1.......................................

9 Gas valve 12............................................

10 Activation, contactor 12...................................

11 Processor 12............................................

TECHNICAL DATA 13..................................

MAINTENANCE 13....................................

SETTING THE WIRE FEED PRESSURE 14...............

CONTROL PANEL AND CONNECTIONS 15..............

ACCESSORIES 16.....................................

SPARE PARTS LIST 17.................................

NOTES 24............................................

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 d escription 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
May 2002.

The MEK 2 is 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.

Rights reserved to alter specifications without notice.

cmek2de1

-- 2 --

WARNING !

STATIC ELECTRICITY can damage circuit
boards and electronic components.

SSSS Observe precautions for handling electrostatic

sensitive devices.

ESD

SSSS Use proper static--proof bags and boxes.

WARNING

ARC WELDING AND CUTTING CAN BE INJURIOUS TO YOURSELF AND OTHERS. TAKE PRECAU­TIONS 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.

READ AND UNDERSTAND THE INSTRUCTION MANUAL BEFORE INSTALLING OR OPERATING.

PROTECT YOURSELF AND OTHERS!

WARNING!

Rotating parts can cause injury, take great care

-- 3 --cmek2de1

COMPONENT DESCRIPTION

This component description refers to the connection diagram. In the description of operation
on page 7 there is a more detailed description of the components and their function.

AP01 Main circuit board with control electronics.
C01 Capacitor 0.1 ←F 125 VAC, decoupling.
G01 Tachogenerator, incorporated in motor M01.
M01 Motor, rated voltage 24 V.
R3 Potentiometer, for setting the burn--back time.
RP01 Potentiometer, 10 kτ, for setting the wire feed speed.
SW1 Switch, 2/4--stroke changeover.
SW2 Switch, creep start ON/OFF
XP01 23--pole connector, for connection to the welding power unit.
XP02 Terminal for welding current connection from the power unit.
XS01 -- XS09 Sleeve connectors.
YV01 Solenoid valve

cmek2de1

-- 4 --

CONNECTION DIAGRAM MEK 2

The numerals 1 -- 11 refer to the description of operation.

R3

0V

cmek2e01

-- 5 --cmek2de1

DESCRIPTION OF OPERATION

Component positions, circuit board AP01

cmek2de1

cmek2e02

-- 6 --

Sections1to11belowrefertothediagramonpage5.
The circuit board is screened by a metal casing, connected to 0 V in the wire feed unit.

1 Power supply

The feeder obtains a 42 V supply from the control power supply tr ansformer in the
power unit via contact XP01. Its power demand at maximum load is 3.5 A.

42 V AC is used for the welding torch trigger switch and as the power supply to the
gas solenoid valve and the main contactor. In addition, 42 V is also available on
contacts H01 and H02.

cmek2e09

Rectifier BR1 rectifies the 42 V supply to 60 V. Capacitor C28 smooths the voltage,
which then supplies the wire feeder motor.

Transistor Q8 is a pre--regulator which reduces the voltage from 60 V to 20 V. Q8 is
current--limited to about 200 mA. If the 20 V supply drops below 13 V, the wire
feed unit stops.

VR1 and VR2 are 5 V and 15 V voltage regulators respectively.

-- 7 --cmek2de1

2 2--stroke / 4--stroke

2--STROKE

When SW1 is open, the unit operates in 2--stroke mode. Operating the trigger on the
welding torch starts the motor, opens the gas valve and energises the power unit
contactor.

Releasing the trigger stops the motor, de--energises the contactor and closes the gas
valve. If burn--back is in operation, welding ceases when the burn--back time has
elapsed.

4--STROKE

When SW1 is closed, the unit operates in 4--stroke mode. Operating the trigger on
the welding torch opens the gas valve: releasing the trigger then starts the motor and
energises the power unit contactor.

cmek2e08

Operating the trigger switch for a second time stops the motor and de--energises the
contactor in the power unit: releasing the switch then closes the gas solenoid valve.
If burn--back is in operation, welding ceases when the burn--back time has elapsed..

3 Start / Stop

The welding torch switch is supplied with 42 V AC. Closing the switch activates
optocoupler IC1, causing the voltage across C35 to go low.

cmek2e07

cmek2de1

-- 8 --