ESAB LTR 160 is a primary-switched power unit with parallel-connected MOSFET-transistors as switching elements, designed for TIG and MMA welding.
ESAB LTR 160 is a primary-switched power unit with parallel-connected MOSFET-transistors as switching elements, designed for TIG and MMA welding.
0740 800 104
Valid for serial no. 704--xxx--xxxx to 011--xxx--xxxx040830
LTR 160/200
Power Tig 160/200
Service manual
-- 2 --conte
LIST OF CONTENTS Page
READ THIS FIRST 3................................................................
COMPONENT DESCRIPTION 4......................................................
WIRING DIAGRAM LTR 160 Valid for ser .no. 704 -- 726 7..............................
WIRING DIAGRAM LTR 160 Valid from ser.no. 842--xxx--xxxx 8.........................
WIRING DIAGRAM LTR 200 Valid for ser .no. 722--xxx--xxxx to 842--901--0271 10...........
WIRING DIAGRAM LTR 200 Valid from ser.no. 842--902--xxxx 12.........................
DESIGN CHANGES 14...............................................................
DESCRIPTION OF OPERATION CIRCUIT BOARD AP01 15..............................
1 +30 V +20 V ±10 V Power supply 15............................................
2 Power supply to the fan 16.......................................................
3 Selection of welding method 16...................................................
4 Start / Stop, Reference input, Remote control input 17..............................
5 Slope up / Slope down 18........................................................
6 HF unit 18.....................................................................
7 Gas valve 19...................................................................
8a Shunt input 19..................................................................
8b Shunt input with shunt signal amplifier 20..........................................
9 Arc voltage sensing 21..........................................................
10 Gate circuit 22..................................................................
Checking the gate pulses 23.....................................................
11 Thermal overload switch 24......................................................
Component positions, circuit board AP01 0481 864 880 25.............................
Component positions, circuit board AP01 0481 818 880 26.............................
TRANSISTOR BOARD AP02 28......................................................
TRANSISTOR BOARD AP03 30......................................................
MOS TESTER 32....................................................................
SOFT STARTING 33.................................................................
LTR 160, SUPPRESSION CIRCUIT BOARD AP08 34...................................
LTR 200, SUPPRESSION CIRCUIT BOARD AP08 34...................................
SUPPRESSION CIRCUIT BOARD AP09 35............................................
DISASSEMBLY / REASSEMBLY 36....................................................
Assembling the diode modules 36....................................................
Removal of transistor circuit boards AP02 and AP03 37.................................
Refitting the transistor circuit board 37................................................
Fitting the main transformer TC02 38.................................................
LOAD CHARACTERISTICS 39........................................................
TECHNICAL DATA 40................................................................
INSTRUCTIONS 41..................................................................
INTRODUCTION 41.................................................................
INSTALLATION
41..................................................................
OPERATION 42.....................................................................
MAINTENANCE 44..................................................................
SPARE PARTS 44...................................................................
NOTES 45..........................................................................
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 wiring diagram as a form of index for the description of operation. The cir cuit
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.
The manual is valid for LTR 160 and LTR 200 with serial numbers:
704--xxx--xxx, 722--xxx--xxxx, 726--xxx--xxxx, 842--xxx--xxxx, 011--xxx--xxxx.
The LTR 160 and LTR 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
This component description refers to the wiring diagrams for LTR 160 and LTR 200.
The LTR 160/200 are a 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 the description on
page 15 and DESIGN CHANGES on page 14.
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.
AP08 Interference suppression circuit board. Prevents mains--borne interference,
see the circuit diagram on page 34.
AP09 Interference suppression circuit board, remote control connector, see the
circuit diagram on page 35.
AP10 Circuit board with shunt signal amplifier. See the description on page 20.
Included in the LTR 160 from serial number 842--xxx--xxxx. and in the
LTR 200 from serial number 842--902--xxxx.
AP11 HF generator. See the description on page 18.
C01 Transient protection.
C02 Capacitor, 1000µF, buffer/smoothing capacitor. Time to discharge after
turning off the unit: about two minutes.
C03 See C02. Only fitted in the LTR 200.
C04 -- C09 Decoupling capacitors.
C10 2 -- capacitors, 12 nF. Protection against transient voltages. From serial
number 011--xxx--xxxx the capacitors are replaced by L04 and L05.
EV01 Fan, 24 VDC
-- 5 --cltr0de1
FU01 -- FU06 Fuses fitted to the control transformer. For fuse ratings: see item 212 in the
spare parts list. Early versions of the machines have no fuses.
HL01 Lamp, 28 V, white, lights when mains power is on.
L01 Secondary inductor.
L03 Primary inductor, improves the machine’s form factor, i.e. reduces the
mains load. Only included in the LTR 160.
L04, L05 Ferrite ring cor es, transient voltage protection.
Replaces C10 from serial number 011--xxx--xxxx.
L06 Ferrite tube, transient protection for machines without shunt signal
amplifier. The shunt signal wires are twisted and wired three turns through
the tube. See
DESIGN CHANGES on page 14.
QF01 Mains power supply switch.
R01 Resistor, 3.9 kΩ 5W.
R02 Resistor, 4.7 kΩ.
RP01 Potentiometer 500 kΩ. For gas post flow time 5 -- 20 seconds.
RP02 Potentiometer 500 kΩ. For slope down time 0.1 -- 10 seconds.
RP03 Potentiometer 10 kΩ 2 W, for setting of the welding current.
RS01 Shunt, 137 mV at 160 A respektively 200 A. The wires B1 and B2 must be
twisted in machines without shunt signal amplifier, AP10.
SA01 Switch, 2/4--stroke changeover.
SA02 Selector switch: TI G Lift Arc / TIG HF / MMA
SA03 Switch, activation of remote control.
ST01 Thermal overload cutout, for overload protection, mounted on the m ain
transformer (TC02) winding. See: Thermal overload switch on page 24.
TC01 Control power transformer. Secondary output voltages of 26, 2x18, 19, 23
and42V.
TC02 Main transformer. For fitting instructions, see page 38.
TV01 HF coil.
V01, V02 Mains rectifier bridge, 35 A, 1200 V. V02 is only fitted in the LTR 200.
After r eplacing the rectifier bridges, the machine must be soft--started: see
instructions on page 33.
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V03,V04 Rectifier and freewheel diodes.
V03 rectifies the welding current. During the time interval between two
voltage pulses from transformer TC02, the fr eewheel diode V04 maintain
the welding current from inductor L01.
On the cooling fins in the LTR 160 is one diode module m ounted and in the
LTR 200 there are two. Each diode module has two diodes. For
installation instructions, see page 36.
V05 LED, yellow. Lights when thermal switch ST01 operates (breaks) as a
result of high temperature.
X01 -- X02 Terminal block.
XP01 Pin connector with jumper. Connected when the machine is used without
water cooler.
XS . . Sleeve connectors.
Note: the connectors XS01, XS02, XS03, XS05 and XS06 has changed
design. Valid for LTR 160 from serial number 842--xxx--xxxx and for
LTR 200 from serial number 842--902--xxxx.
The sleeve numbering is reversed compared to the earlier version. The
wire numbering and the numbering of the contact pins of the circuit board
is not changed, compare the diagrams on page 10 and 12.
The ordering numbers for t he connectors are listed under item 303 in the
spare parts list.
XS10 12--pole Burndy contact, for connection of remote control unit.
XS11 TIG central connector: only LTR model --880 and --882.
XS12 2--pole Cannon connector, only LTR model --881 and --883.
XS13 Welding current connector, OKC, only LTR model --881 and --883.
XS14 Welding current terminals, (two), OKC type.
XS24 Connection for 400V to water cooler. (The water cooler is an accessory,
which is mounted under the machine.)
XS25 Connection for water flow guard.
YV01 Solenoid valve
WIRING DIAGRAM LTR 160 Valid for ser .no. 704 -- 726
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-- 8 --
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WIRING DIAGRAM LTR 160 Valid from ser.no. 842--xxx--xxxx
-- 9 --cltr0de1
-- 1 0 --
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WIRING DIAGRAM LTR 200
Valid for ser .no. 722--xxx--xxxx to 842--901--0271
-- 1 1 --cltr0de1
-- 1 2 --
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WIRING DIAGRAM LTR 200 Valid from ser.no. 842--902--xxxx
-- 1 3 --cltr0de1
-- 1 4 --
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DESIGN CHANGES
LTR 160/200 without shunt signal amplifier
LTR 160 units having serial number s 704--xxx--xxxx and 726--xxx--xxxx, and LTR 200 units
having serial numbers 722--xxx--xxxx, have sometimes suffered from problems. The gas
valve can open as a result of interference from other machines working on the same
workpiece, and there is sometimes also noise from the TIG arc on the machines.
Most of the machines that have suffered from interference problems have been put right by
fitting the conversion set described below. The order ing number for the set is 0458 024 880,
and it is suitable for all LTR 160/200 with serial numbers as listed above. It comprises a
modified control card (E481 864 880), an interference suppression card (0486 187 883) and a
ferrite tube with connections for soldering it into the shunt cables.
The above control card and interference suppression car d are also suitable for use with
LTR160/200 machines that have not been converted by fitting the entire set.
Location of the L06 ferrite tube
1. Replace the AP01 control card and the AP09 interference suppression card.
2. Cut wire B1. BE CAREFUL! Do not mix up the wires. If you mix up B1 and B2, you
will get a current surge that will destroy the machine.
3. Slide a 40 mm insulating sleeve over each end of the wire.
4. Solder the red wire of the ferrite tube between the two cut ends of B1.
5. Cut wire B2. BE CAREFUL! Do not mix up the wires.
6. Slide a 40 mm insulating sleeve over each end of the wire.
7. Solder the black wire of the ferrite tube between the two cut ends of B2.
8. Slide the insulation sleeves over the joints and secure the whole with cable ties.
LTR 160/200 with shunt signal amplifier
LTR 160 machines with effect from serial number 842--xxx--xxxx, and LTR 200 machines
with effect from serial number 842--902--xxxx, have a new AP01 control card and an
amplifier card (AP10) mounted on the shunt. The L06 ferrite tube is not fitted to these
machines, and the new control card is not suitable for use in older machines.
-- 1 5 --cltr0de2
LTR 160/200, new HF g en erator and recifier un it
New HF generator from ser. no. xxx--006--xxxx. See the description on page 18.
New design of the rectifier unit from ser. no. 011--xxx--xxxx. See C10, L04 and L05 in the
component description and items 430 and 530 in the spare parts list.
DESCRIPTION OF OPERATION CIRCUIT BOARD AP01
This description refers to the wiring diagrams and to the components layout diagrams.
Only those items that are connected to the inputs and outputs of the circuit board are
described here.
If there is a fault on the circuit board, the whole circuit board must be replaced.
After replacing the board, the machine must be soft--started, as described on page 33.
1 +30 V +20 V ±10 V Power supply
+30 V
Power supply to the gas and HF relays.
±10 V
Voltage tolerance ±5%. The power supply from transformer TC01 is protected by
two 1.25 A slow-- blow fuses.
+20 V
Power supply to the control amplifier, the pulse width modulator and the gate
circuits.
Voltage tolerance ±5%. The power supply from transformer TC01 is protected by an
800 mA slow--blow fuse.
Capacitor C93 slows the rise time of the 20 V supply at power--on, which delays the
gate pulses to the MOSFET transistors.
HL01 is an indicating lamp on the front of the machine, lighting to indicate that the
main power switch is On.
-- 1 6 --
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2 Power supply to the fan
The LTR is fitted with a DC--powered fan. It is supplied at 28 V ±5% from voltage
regulator VR5. The power supply from transformer TC01 is protected by a 630 mA
slow--blow fuse.
3 Selection o f weld ing metho d
MMA, LiftArc, HF
Switch SA02 selects the welding method by disabling, through a diode network, the
functions that are not to be active for a particular welding method.
2--stroke/4--stroke
Closing switch SA01 selects 2--stroke control mode.
-- 1 7 --cltr0de2
4 Start / Stop, Reference input, Remote control input
Reference input/Remote control input
This input has its own power supply and a high--impedance input to the control
amplifier. T his protects it against short circuits between the remote control cable
and the welding circuit.
Voltage regulator VR1 incorporates internal thermal protection against overload.
At the l owest current reference, the voltage at circuit board contact C9 is 0 V. At the
maximum current refer ence, the voltage is about 14 -- 15 V.
Resistor R74 adjusts the output voltage from VR1 so that the reference voltage and
the control amplifier provide the correct maximum current. This r esistor is adjusted
during manufacture of the circuit board, and should not subsequently be adjusted.
Switch SA03 selects adjustment of the welding current from the remote control
device or from the front panel of the machine.
If it is the Remote position, but no remote control device is connected, resistor R75
holds the current refer ence at the minimum level.
Start/Stop
When operating in TIG welding mode, the machine is started from the welding torch
switch, which is connected to the machine via contacts XS11/XS12. Alternatively,
welding can be started from a remote control device and connectors J and K in
remote control unit contact XS10. Relay RE1 is used only during TIG starts. See
also the description of arc voltage sensing on page 21.
-- 1 8 --
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5 Slope up / Slope down
Potentiometer RP02 on the front of the machine is used for setting the Slope Down
time (the decay time for the welding current when T IG--welding). The time is
adjustable between 0.1 and 10 seconds.
Potentiometer R58 on the circuit board controls the S lope Up time (the rise time for
the welding current when TIG--welding). It is adjustable between 0 and 5 seconds.
On delivery, the Slope Up time has been set at 0.
6 HF unit
WARNING! dangerous voltage.
When the torch switch is closed and the open--circuit voltage exceeds about 45 V,
relay RE3 closes and activates HF unit AP11. The relay drops off when the arc
voltage is less than 45 V or if the arc has not struck within 0.5 seconds.
In the MMA welding mode, transistor Q7 is held off by --10 V from diode D18. In
the Lift Arc mode, Q7 is held off by --10 V f rom diode D17.
The voltage on the primary side of HF transformer TV01 is about 400 V, and the
secondary voltage is about 8 kV.
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.
-- 1 9 --cltr0de2
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.
7 Gas valve
Gas valve YV1 is controlled by relay RE2. Potentiometer RP01, on the front panel
of the machine, is used for adjusting the gas post--flow time in the range 5--20
seconds.
Potentiometer R30, on the circuit board, controls the gas pre--flow time between 0
and 5 seconds. When delivered, it is set at 0 seconds.
The gas valve is activated briefly when the machine is energised.
8a Shunt input
Shunt input for the LTR 160 with serial number 704--xxx--xxxx and 726--xxx--xxxx and
for the LTR 200 with serial number 722--xxx--xxxx up to 842--901--0271
LTR 160: The shunt provides a signal o f 137 mV at a welding current of 160A.
LTR 200: The shunt provides a signal o f 137 mV at a welding current of 200A.
The cables (B1 and B2) between the shunt and the circuit board must be twisted in
order to prevent any interference reaching the circuit board.
Do not mix up cables B1 and B2, it will cause over current which destroys the
output transistors.
-- 2 0 --
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8b Shunt input with shunt signal amplifier
Shunt input for the LTR 160 from serial number 842--xxx--xxxx and for the LTR 200
from serial number 842--902--xxxx
The shunt signal amplifier boar d AP10 is voltage supplied from circuit board AP01.
Resistor R16 adjusts the offset voltage of amplifier IC1. This resistor is adjusted
during manufacture of the circuit board, and should not subsequently be adjusted.
The signal amplification is set by fixed resistors and it is not adjustable.
The shunt voltage is 137 mV at maximal welding current, 160 respectively 200 A.
The voltage between the contacts B1 and B2 on circuit board AP01 must be 5.7 V
±2% at maximal welding current.
Component positions, circuit board AP10
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ESAB LTR 160 is a primary-switched power unit with parallel-connected MOSFET-transistors as switching elements, designed for TIG and MMA welding.
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