Kemppi miniarc 140 User manual

Troubleshooting guide
Ver 1.0

Contents
Technical data……………………………………….
Operation principal…………………………………..
Main circuit………………………………………….
Troubleshooting chart……………………….…...….
Main circuit diagrams……………………………….
Functional tests/measurings…………...............…….
Measuring points…………...……...…..
Main transformer T001 prim. Voltage...
Main transformer T001 sec. Voltage......
Voltage after secondary rectifier…........
IGBT gate pulse…………………..…...
Control card A001 connectors…………………...….
Control card A001 layout…………………....……...
IGBT-transistor testing…….............………………..
Secondary diodes testing…………….……………...
Service infos………………………….....…………..
Notes………………………………….............……..
3
4
4
5
6
7
7, 8
8, 9
9, 10
10, 11
11-13
14
15, 16
17
17
18-20
21

Minarc 140 Minarc 110
Supply voltage, 1~50/60 Hz 220 V –10%…240 V +6% 220 V –10%…240 V +6%
Loadability 35%ED 140 A (7,5 kVA)
50%ED 110 A (5,5 kVA)
100%ED 100 A (5,1 kVA) 80 A (3,9 kVA)
Connection cable / fuses 2.5 mm² S / 3,3 m 16 A 1.5 mm² S / 2.0 m 13 A
Welding current range MMA 10 A / 20.5 V…140 A /
25.6 V 10 A / 20.5 V…140 A / 25.6 V
Stick diameter ø 1.5…3.25 mm ø 1.5…2.5 mm
Welding current adjustment Portaaton Portaaton
OCV + 105 V * + 105 V *
Idling power < 10W < 10W
Efficiency 0.8 0.8
Power factor 0.60 (140 A / 25.5 V) 0.60 (110 A / 24.4 V)
Temperature class B (130°C) / H (180°C) B (130°C) / H (180°C)
Operating temperature -20…+40°C -20…+40°C
Stock temperature -40…+60°C -40…+60°C
Casing class IP 23C IP 23C
Norms IEC 974-1 IEC 974-1
EN 50199 EN 50199
Measures Length 305 mm 305 mm
Width 123 mm 123 mm
Height 250 mm 250 mm
Weight 4.2 kg (4.8 kg) 4.2 kg (4.6 kg)
* From serial number 1085088/M onwards the OCV is approx. + 85 V
Technical data
3

Operating principal
VDC
t
105
13µs
Max. 0,5
n. + 320 V
1/3
V1
V2
When IGBT-transistors V1 and V2 are not conductive, no power is transferred. The power is
adjusted by changing the IGBT-transistors conductive timings (PWM).
Main circuit
+ t + t
X3
X1
X2
R69R70
L2
C28
C22C5
L1
R59 R54
C43
V26 V23
V9
C1, C2, C3
V5, V32
V1, V31
V2, V3, V4V6, V7, V8
T001T2
K1
T001
U
R64
U
V29, V30
C39 R65
R66
C38
V27, V28
R63
X18
X17
L001
L002
X003
X004
X16
X3
X2
Z001
Minarc power sources are ”dual-Forward”-inverter power sources, controlled by PWM method.
The switching components are IGBT-transistors. Inverter operating frequency is approx. 80 kHz.
Below is a picture of the ”dual-forward”-inverter operating principal:
4

General
DISTURBANCE POSSIBLE CAUSE REMEDY
Power source not starting; OCV ~
0 V; Yellow overheat led H001
blinking.
Fan M001 Disconnect the fan connector X15
and start the power source. If the
power source starts and the OCV
rises, then replace the fan.
Secondary choke L001 in short
circuit with minus pole X004.
Add an insulator ring to the minus
pole X004. See service info 02 /
2002, page 18.
Secondary rectifier diodes in
short circuit.
Check the secondary rectifier
diodes condition and replace if
needed. See secondary diodes
testing, page 17.
Faulty primary circuit power
semiconductor.
Check primary side power
semiconductors. If the voltage over
PTC-resistor R59 is over 230 Vac,
there is a short circuit in the
primary side. Replace the faulty
power semiconductor. See IGBT-
transistor testing, page 17.
Diode V24 is in short circuit on
control card A001.
Check the diode, and replace if
needed.
Faulty control card A001. Replace control card A001
The power source starts and the
OCV rises to 85 V, after which
the power source shuts down;
The power source can´t be
loaded.
Relay K1 Check the relay operation. See the
service info 03 / 2002, page 19.
Welding current can´t be adjusted
by the potentiometer R001.
Faulty potentiometer R001. Check the potentiometer condition
(R001 = 10 kΩ)
Faulty control card A001. Replace the control card A001.
5
Machine repairs may only be done by a company or repairman authorized to do the work!
First check visually if there are any signs of damage in the machine, for example loose wires,
breaks or signs of overheating.
Troubleshooting chart

Main circuit diagrams
Main circuit diagram from serial number 1085088/M onwards (OCV approx. + 85 V)
Main circuit diagram, before serial number 1085088/M (OCV approx. + 105 V)
6

Functional tests / measurings
1
2
3
Measuring point 1. Main transformer T001 primary voltage
Measuring point 2. Main transformer T001 secondary voltage
Measuring point 3. Voltage after the secondary rectifier
7

Measuring points on the control card A001
Main tranformer T001 primary voltage, 10 A
Measuring point 1. Main tranformer T001 primary voltage
1
2 3
4
8

Päämuuntajan T001 ensiöjännite, 140 A
Measuring point 2. Main transformer T001 secondary voltage
Main tranformer T001 secondary voltage, 10 A
Measuring point 1. Main transformer T001 primary voltage
9

Main transfomer T001 secondary voltage, 140 A
Measuring point 3. Voltage after secondary rectifier
Voltage after the secondary rectifier, 10 A
Measuring point 2. Main transformer T001 secondary voltage
10

Measuring point 4. IGBT gate pulse
IGBT gate pulse, 10 A
Measuring point 3. Voltage after the secondary rectifier
Voltage after the secondary rectifier, 140 A
11

IGBT gate pulse, 140 A
IGBT gate pulse, 60 A
Measuring point 4. IGBT gate pulse
12

IGBT gate pulse with open circuit (OCV approx. + 105 V)
Measuring point 4. IGBT gate pulse
IGBT gate pulse with open circuit (OCV approx. + 85 V)
13

Control card A001 connectors
X15
X19
X3
X2
X1
X16
X18
X17
X004
X4
X5
X6
X7
X8
X24 X23 X10
X11
X14
X13
X12
X9
X20
Connector Signal
X1, X2 Net voltage 230 Vac
X3 Protective earth
X4, X6, X8 Current adjustment
potentiometer R001
X5, X7 MMA/TIG-selection switch
S002
X9, X11 Main transformer T001
auxiliary coil
X10, X12 Main transformer T001 PTC
RT101
X13, X14 Primary profile PTC RG201
X15 Fan
X16, X17 Main transformer T001
secondary
X18 Secondary choke L001
X19, X20 Main transformer T001 primary
X23 PWM-circuit N1 VFB, pin 2
X24 + 5 V
14

Control card A001 layout
X4
The older version control card A001, 4292730
The new control card A001, 4298870 15

Control card A001 layout
EMI-filter
Intermediate circuit charging
(Rele 9766230)
Rectifier unit
(9750191)
Smoothing capacitors
(9755615)
IGBTs and opposite diodes
(IGBT-set 4297750)
Secondary rectifier unit
(4297740)
LED
(9775757)
Varistors
(95 V 9753590, 175 V 9753588)
16

IGBT-transistors testing
GCE
IGBT-TESTER
TR1TR2
CONTROL
OFFON
B2/6
C2E1/1
E2/2
C1/3
B1/4
Discrete-IGBT (50 A, 600 V) can be tested with the IGBT-tester.
When replacing damaged IGBT-transistors the whole set
must be always replaced. The gate resistors (10Ω) must be checked
and replaced if necessary. Spare part IGBT set 4297750.
Discrete-IGBT tightening torque to the heatsink is 0,6…1,2 Nm!
Testing the secondary diodes
When testing the secondary diodes the other coil end of the main
transformer T001 has to be disconnected. The main transfomer
coils and connectors may not be bent!
If the secondary diodes are in short circuit, the power source
doesn´t start.
Secondary rectifier unit 4297740.
The tightening torque for the secondary diodes is 0,6…1,2 Nm!
Solderings should be done carefully, because of high currents,
approx. 30 A/ leg!
60 A, 200 V types APU02 or 2141
60 A, 400 V types APU04 or 2154
17

Service infos
02 / 2002 Minus pole insulator
Power sources
Minarc 110 & 140
Modification
An insulator 9771963 is added to the minus-pole. See the attached picture.
Reason for midification
Secondary choke may cause a short circuit between plus- and minus-poles. This is prevented
by installing the inslulator 9771963 to the minus-pole.
Production
The modification is valid from serial number 1023532/K onwards.
Power sources with serial number before 1027716/K
The modification can be carried out during service or repair work.
18

Service infos
03 / 2002 IGBT gate resistors and intermediate circuit charging relay
Power sources
Minarc 110 & 140
Modification
IGBT gate resistors (10 ohm.) have been added to the spare part set (4297750).
Reason for modification
If the IGBTs are damaged, also the gate resistors (R2, R4, R5, R6, R7 and R8) may be damaged.
For example if one resistor has been destroyed, then the IGBT doesn´t get gate control and this
causes overload to the other IGBTs. When IGBTs are replaced then the gate resistors must be
checked too. See the attached picture.
DC-link(Intermediate circuit) charging relay K1 (9766230)
If fan rotating speed drops after the machine starts and the OCV is max. 85 volts, then most
likely the DC-link charging relay is not working. In some cases there has been lacquer inside
the relay and it is stuck. Relay control voltage is approx. +28 volts.
19

Service infos
20 / 2002 A new control cardi A001 and filter card Z001
Power sources
Minarc 110 and 140
Modification
Control card A001 and filter card Z001 have been replaced with new versions. The new spare
part codes are as follows:
Power source Control card A001 Filter card Z001
MINARC 140 4298870 4298600
MINARC 110 4301880 4298600
Reason for modification
The OCV is lowered to 85 Volts.
Compatibility
The new and old card versions are compatible. NOTE !! Only a combination of a new control
card A001 (4298870, 4301880) and a new filter card Z001 (4298600) lowers the OCV to ~ 85
Volts. See the chart below:
Power source Control card A001 Filter card Z001 OCV
MINARC 140 4298870 (new version) 4298600 (new version) ~ 85 VDC
MINARC 140 4298870 (new version) 4294620 (old version) ~ 105 VDC
MINARC 140 4292730 (old version) 4298600 (new version) ~ 105 VDC
MINARC 110 4301880 (new version) 4298600 (new version) ~ 85 VDC
MINARC 110 4301880 (new version) 4294620 (old version) ~ 105 VDC
MINARC 110 4294440 (old version) 4298600 (new version) ~ 105 VDC
Production
The modification is valid in production onwards from the following serial number:
MINARC 110/140 1085088/M
Stock
Only cards of the new type are available.
Power sources manufactured befre serial number 1085088/M
OCV lowering is not warranty covered.
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