Thermal Arc 300GTSW Pro-Wave, Service Manual

Page: 65 / 130

pro-wave 300gtsw
June 21, 2012
6-27
power oFF test procedure
1. Set the diode test scale on the digital meter.
2. For Q1, check the diodes between:
TB3 and TB1
TB4 and TB1
3. For Q2, check the diodes between:
TB5 and TB2
TB6 and TB2
A. To check the gate drive resistances for Q1 and
Q2 unplug CN8 and CN9 from the MAIN PCB.
Should measure 2.18kW.
CN8/CN9 plug PIN 1 to PIN 2
CN8/CN9 plug PIN 4 to PIN 5
4. For Q3/Q4, check the diodes between:
A quick check can be made across the POSITIVE
and NEGATIVE output terminals.
Set the meter to ohms and check the resistance
across the weld terminals and the reading should
be 2.5kW.
5. For Q3/Q4 check the diodes between;
Brown wire on the filter choke to the POSITIVE (+)
OUTPUT TERMINAL.
Gray wire on the filter choke to the POSITIVE (+)
OUTPUT TERMINAL.
6. If a component on the Q3,Q4 gate board (PCB9)
is damaged then the Driver PCB (PCB8) should
be checked.
A. Disconnect CN2 from PCB8.
B. Check the gate resistance on PCB9 between E1
to G1 and E2 to G2. Reading should be 1.1kW.
C. Check gate drive on PCB8 at CN2 between
CN2-1 to CN2-2 and CN2-4 to CN2-5. Reading
should be 1kW.
Pin 1
White
Black
Pin 2
Pin 4 Pin 5
White
Red (CN8, PCB1)
Orange (CN9, PCB1)
Blue (CN1, PCB8)
Art # A-06128
Figure 6-24: Plug orientation for IGBT inverter power
OFF test
For Q3/Q4, refer to figure 6-25, then:
7. With the digital meter on the diode test scale,
measure between bus bars A-B and B-C.
8. On PCB1 mounted to Q3/Q4 there are 4 sets of
points E1G1, E2G2, E3G3, E4G4. Check each of
these with a meter on diode scale. A short is a bad
indication. If a short is detected remove the bus
bars and test individually to determine which is
bad Q3 or Q4.
A B
C
Art # A-06129
Figure 6-25: Q3/Q4 IGBT inverter measurement points