circuit opto-insulators are attached).
4) Checking power and signal wiring
It is important to check that all the connections are in good condition
Secondary board (figure 6):
and the connectors are inserted and/or attached correctly.
A)
Power diodes D1, D2, D3, D4, D5.
To do this, take the cables between finger and thumb (as near as
possible to the fastons or the connectors) and pull gently outwards: the
B)
Thermostatic capsule on the dissipator
cables should not come out of the fastons or connectors.
C)
Shunt R1
Power transformer and inductance assembly
(if the primary board
has to be removed, otherwise it can be cleaned superficially from the
secondary board side).
In particular on the
primary board
(figure 3)
it is necessar y to check:
A)
The connections R,S,T (J3, J4, J5) of the 3 phases to the main
switch and upstream of the switch: input filter and power supply
cable.
B)
The 2 connections between the primary board and the power
transformer (PIN1TRAFO and PIN2TRAFO).
3) Visual examination of the machine
C)
The power supply connections for the 2 fans to J9, J10, J11, J12).
Make sure there is no mechanical deformation, dent, or damaged
and/or disconnected connector.
In particular on the secondary board
(figure 6)
the following checks
Make sure the power supply cable has not been damaged or
should be made:
disconnected internally and that the fans work correctly with the
A)
Connections between the power transformer and the 2 secondary
machine switched on. Make a visual check of components listed below
board bushes.
for signs of burning or breakage:
B)
Correct connection for the output equalisation inductance (between
A) Main power supply switch (figure 2B)
the secondary board bush and machine outlet OUT-).
Use the multimeter to check whether the contacts are stuck together
C)
Connections to the shunt (secondary dissipator, shunt reader and
or open.
shunt e positive machine outlet OUT+).
Probable cause:
D)
The wiring between the thermostatic capsules on the secondary
Mechanical or electrical shock (e.g. bridge rectifier or IGBT in short
dissipator and the power transformer (connected in series).
circuit, handling under load).
B) Current potentiometer R72 (figure 2A)
Probable cause:
5) Electrical measurements with the machine
mechanical shock.
switched off
C)
Welding mode selector switch S1 (figure 2A)
With the digital multimeter set for diode testing check the following
Probable cause:
components (junction voltages not less than 0.2V):
mechanical shock.
A)
Rectifier bridges D10, D19
(figure 5)
.
D)
Input filter board varistors (figure 4)
B)
IGBT's Q3, Q4, Q5, Q12, Q13, Q14 (absence of shor t circuits
Probable cause:
between collector-gate and between collector-emitter
figure 5
).
power supply voltage much higher than 400Vac.
C)
Diodes D1, D2, D3, D4, D5 on secondary board between anode
E) Relays K1, K2 primary board (figure 5)
and cathode
(figure 6)
.
Probable cause:
See main power supply switch
N.B.
If the relay contacts are stuck together or dirty, do not attempt to
With the digital multimeter set on ohms check the following
detach them and clean them but replace the relay.
components:
F) Electrolytic capacitors C6, C17, C38, C45 primary board
A)
Resistors R3, R9: 47 ohm ±5% 7W (precharge
figure 5
).
(figure 5)
B)
Resistors R1, R2, R69, R71: 10 ohm ±10% 11W (primary snubber
Probable cause:
figure 5
).
- mechanical shock
C)
Resistor R1: 10 ohm ±10% 5W (secondary snubber
figure 6
).
- machine connected to a much higher line voltage than 400Vac,
D)
Continuity test of the thermostatic capsules on the power
- broken rheophore on one or more capacitor: the remainder will be
transformer and secondary board dissipator: disconnect the
overstressed and become damaged by overheating,
fastons
and
- aging after a considerable number of working hours,
measure the resistance over their ends, it should be about 0 ohm
- overheating caused by thermostatic capsule operational failure
(figure 6)
.
G) IGBT's Q3, Q4, Q5, Q12, Q13, Q14 (figure 5)
Probable cause:
- discontinuation in snubber network,
6) Electrical measurements with the machine
- fault in driver circuit ,
- poorly functioning thermal contact between IGBT and dissipator
in operation
(e.g. loosened attachment screws: check),
The tests described below can be used to check the workings of the
- excessive overheating related to faulty operation.
power and control parts of the machine.
H) Primary board diodes D4, D7, D24, D27 (figure 5)
Probable cause:
Preparation for testing.
excessive overheating related to faulty operation.
A)
Disconnect the fastons PIN1TRAFO (J8) and PIN2TRAFO (J2) of
I) Secondary board diodes D1,D2,D3,D4,D5 (figure 6)
the power transformer from the primary board
(figure 4)
.
Probable cause:
B)
Set up the oscilloscope with the voltage probe x100 connected
- discontinuation in snubber network,
between the collector of Q6 (probe) and capacitor C47 from the Q3
- poorly functioning thermal contact between diodes and dissipator
side (earth) on the primary board
(figure 5)
.
(e.g. loosened attachment screws: check),
C)
On the primary board disconnect the jumper JP2.
- faulty connection at machine outlet.
D)
Connect the HV outlet of the HV power supply to the primary board
as follows (figure 5):
(+) Positive
( clamp) to the PIN of connector JP2 from the resistor R75
side,
(-) Negative
(faston) to the negative faston of the diode bridge D19.
E)
Disconnect the wiring connected to the control board and remove
K) Power transformer and filter inductance
the control board (following the instructions given below).
F)
Connect the power supply cable of the machine to a 3-phase variac
with variable output 0-500 Vac.
N.B.
Some versions may have 4 power diodes (D1, D2, D3, D4)
A)
The wiring (J3) towards the primary board (J1).
B)
The wiring (J4) towards the remote control socket (CAD)
C)
The wiring (J1) to the thermostatic capsules, shunts and out-.
Parts fastened to the base (figure 4)
If the primary and secondary boards are removed (with the diaphragm),
clean the input filter carefully.
(so that the thermostats are connected in series)
J) Secondary board shunt R1 (figure 4)
Check whether it has changed colour
Probable cause:
Overheating due to loosening of the screws connecting the
shunts to the secondary circuits.
After gaining access to the components on the base:
L)
Input filter board varistors RV1, RV2, RV3 (figure 4)
Probable cause:
power supply voltage much higher than 400Va
SUPERIOR 240 CE
13
