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Service manual
Fitweld 300
Version 1.2
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Technical data
4 x 1,5 mm² (5 m) / 10 A delayedConnection cable / fuse
Filler wires 0,8 – 1,2 mm
0,8 – 1,2 mm
0,8 – 1,2 mm
1,0 – 1,2 mm
Fe solid
Fe cored
Ss
Al
14,5 KgWeight
External dimensions (L x W x H) 457 x 226 x 339 mm
200mm
Spool, max ø
0,85MIGEfficiency at max. current
0,95MIGPower ratio at max. Current
43 VOpen circuit voltage
20 A / 11 V – 300 A / 32 VMIGWelding range
300 A / 29 V
220 A / 25 V
180 A / 23 V
140 A / 21 V
Max. 11 kVA
3~400 V -15%/+10%, 50 / 60 Hz
ED 20%
ED 40%
ED 60%
ED 100%
MIG
Load capacity 40 °°°°C
Rated power
Supply voltage
The device may be repaired only by a person legally authorized
perform electric work!
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User interface
2
3
4
6
1. Welding voltage adjustment
2. Wire feeding adjustment
3. ON signal lamp
4. Overheat protection lamp
5. No gas warning lamp
6. Euro connector
Front Plate
1
5
9
7
8
Back Plate
7. Gas connector
8. Main switch
9. Ground cable connector
12
10 11
13
Spool room
10. 2T no gas/2T/4T switch
11. Gas flow adjustment
12. Spool room light
13. Polarity selection
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Construction
Z002
Z001
P001
A001
Gas valve
Wire feeder
motor
Cooling
fans
Gas pressure
switch
Gas flow
adjustment
Tip
If machines cover plate screws thread fails you could
change PT screws diameter to 5,5mm - 6mm.
Note!
Protective earth conductivity test must be performed at
earth points on both the front and back plates
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Main circuit diagram
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Main circuit card Z001
IGBT-moduleCurrent transformer
EMC filtering
Primary rectifier
Gate transformers
- EMC filtering
- Primary rectifier and DC -link charging PTC
- H –bridge (frequency 27kHz)
- Gate transformers and gate drivers
- Auxiliary voltage 15VDC
- Over voltage sensing from DC-link
- Two stage fan start
- PTC protection alerts (signals comes from the main transformer and the
secondary choke)
Functions and components:
15VDC aux. voltage
indicator LED
Jumpers, default settings:
X25 open
X26 closed,
- generator compensation off
X27 open
X28 closed
X29 closed
X32 open
X28
X26
X25
X27
X29
X32
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Main circuit card Z001
Measurement points
DC Link -
DC Link +
L1,L2 and L3
DC-link voltage (with Kemppi multipower):
digital multimeter
1. Feed 22 VAC to auxiliary transformers secondary
connector from Kemppi multipower (connector
must be connected)
2. Measure value from DC-link test points by digital
multimeter
Value: 500 VDC or more
3. Measure secondary voltage (start signal needed)
Value: 30VDC or more
Primary rectifier: Digital multimeter diode
test
1. Red test probe L1, L2, and L3 (one at the
time)
Black test probe DC-link plus
Value: 0,3 - 0,5 VDC -> diodes ok
2. Red test probe DC-link plus
Black test probe L1,L2 and L3 (one at the
time)
Value: No value -> diodes ok
3. Red test probe L1, L2, and L3 (one at the
time)
Black test probe DC-link minus
Value: No value -> diodes ok
4. Red test probe DC-link minus
Black test probe L1,L2 and L3 (one at the
time)
Value: 0,3 – 0,5 VDC -> diodes ok
If values in test 1 or 4 are close to zero rectifier is
short circuited. If value is “no value” circuit is
open
If values in test 2 or 3 are close to zero diodes are
leaking
Auxiliary
transformers
secondary
connector
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Secondary rectifier Z002
Measurement points
Diode branch A
Diode branch B
Common point
Resistor A
Resistor B
Secondary diodes:
1. Measure diode branches one at the time
from transformer (red test probe) to
common point (black test probe)
Values: 0,3 – 0,5 VDC
2. Measure diode branches one at the time
from common point (red test probe) to
transformer (black test probe)
Value: No value
Damping circuit resistors:
Resistor value must be 5Ω
Main components
- Middle point connected full wave rectifier
- Damping circuit reduces voltage stress of diodes
- Overvoltage varistors protect diodes from ignition sparks
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Wire feeder motor control card A001
Adjustments
Wire feed speed maximum:
1. Adjust wire feed speed potentiometer to
maximum
2. Feed wire 10 second by triggering the
torch
3. Measure fed wire length
4. Should be 16,7% of 18m/min (3m/min)
- If wire feed speed is offset, adjust
trimmer and repeat steps 2.-4.
Functions
- Wire motor power feeding from machine’s secondary circuit by MOSFET half bridge
- Wire feed speed maximum adjustment by trimmer
- Spool room light (in different small card)
Tilt and detach
NOTE!
- When installing spare part card you have to check wire feeding speed maximum adjustment level
- Before installing tilt and detach spool room light card
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Panel card P001
Functions
- Supply voltage 24VDC filtering
- Generating reference voltage 3,3VDC
- Voltage adjustment by potentiometer
- Wire feed adjustment by potentiometer
- Start signal throughput (for optional usage)
- Three leds: On, Overheat protection and No gas
Gas pressure switch S002
Functions
- Prevent welding while gas pressure under adjusted level
- Adjusted to 1 bar as a default
- Not functioning in gasless wire mode
Adjustment
1. Connect gas hose to gas connector
2. Adjust pressure to 1 bar
3. Adjust pressure switch alert level to 1 bar
Alert level adjustment
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Installation of semiconductors
The installation surfaces must be clean, even very small particles (0,050mm) between the surfaces
increase the gap between heat sink and module, causing module overheating and possibly
destruction. Heat transfer paste is spread as an even layer about 0,1 mm thick, onto the modules
base plate. The module is immediately attached to the heat sink, in order to avoid any dirt to get
between the components. At first all M5 screws are tightened carefully to torque of 0,5…2 Nm, after
which the module can be tightened to the nominal torque of 3 Nm. After a few minutes the screw
torques are checked again to be 3 Nm.
IGBT mounting onto the heat sink
Secondary diode unit
As described above but screws are torx T-10 and tightening torque 1,2 Nm. Diodes can be tighten
right away to this torque.
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Notes
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