
1
3
ADVANCED TROUBLESHOOTING
13.
5.8 Verification of the secondary
IGBT (Q25-Q26)
CAUTION
Before performing any portion of the procedure
below, make certain the unit is placed in the initial
set up condition as described in section 1
3
.4.1.
"Preparation".
1 ) Check whether there are any abnormalities on
the appearance of PCB17.
2 ) Verify the characteristic of the secondary IGBT
(Q25-Q26), using a diode tester.
3 ) Refer to Table 11-8 and Figure 11-17 for
the checkpoints on Q25-Q26.
Table 1
3
-8: Tester checkpoints in the Q25-Q26
Figure 1
3
-17: Tester checkpoints in the Q25-Q26
13.
5. 9 Verification of No-load Volt-
age (OCV)
CAUTION
Before performing any portion of the procedure
below, make certain the unit is placed in the initial
set up condition as described in section 1
3
.4.1.
"Preparation".
a. Verify the no-load voltage in STICK mode.
1) In STICK welding mode, mark and then
turn potentiometer VR1 on PCB6 (WK-
5549) fully counterclockwise to turn off
the electric shock protector function (Volt-
age-Reduction-Device, VRD).
2) Contactor function is put into the state of
"ON" pushing Function button. Refer to sec-
tion 6.
WARNING
Electric shock hazard. The unit will generate OCV
immediately when contactor function is put into the
state of "ON" pushing Function button enabling
STICK mode.
3) Verify the no-load voltage using a DC volt-
meter.
(The capability of the voltmeter should be
more than 100VDC.)
4) The normal no-load voltage is approxi-
mately 65V.
COMPONENTTE
STED
TERMINALS
ACCEPTABLE
VALUE
Positive
lead
Negative
lead
Collector-Emitter
of Q25
(By PCB18
connection)
C1
C2E1
C2E1
C1
Open
0.2 to 0.5V
Collector-Emitter
of Q26
(By PCB19
connection)
C2E1
E2
E2
C2E1
Open
0.2 to 0.5V
Q25
Q26
C1
E2
C2E1
13-16
June 30, 2008
TRANSTIG 300 AC/DC
SERVICE MANUAL
Содержание TRANSTIG 300 AC/DC
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