CIGWELD TRANSTIG 300 AC/DC, Service Manual, Page: 74 / 134

1
3
ADVANCED TROUBLESHOOTING
13.
5.4 Verification of the Gas Valve,
SOL1, Drive Circuitry
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 ) Verify the voltage between the PIN3 (Positive
[+]) and PIN4 (Negative [-]) of connector CN11
on PCB3 (WK-5548) while you press the torch
switch while in TIG Mode. (The capacity of the
voltmeter should be more than 50VDC.) The
location of connector CN11 of PCB3 (WK-
5548) is indicated in Figure 8. When you mea-
sure the above voltage, do not remove the
connector. Conduct the measurement while
the connector plug and receptacle are still con-
nected.
Figure 1
3
-13: Verification of the SOL1
2 ) Using the measurement taken above, follow
the chart below for possible failure modes.
Table 11-4: Verification of the SOL1
3 ) When verifying the voltage, confirm that the AC
input voltage remain within the operating range
of the unit.
(The AC input does not drop below 180VAC).
13.
5. 5 Verification of the primary
Diode (D1)
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) Verify the characteristic of the primary diode,
D1, using a diode tester.
2) Refer to Table 11-5 and Figure 11-14 for
the checkpoints on D1.
Table 1
3
-5: Tester checkpoints in the D1
Figure 1
3
-14: Tester checkpoints for D1 showing
the interconnection diagram
Voltage
measurement.
(1PIN-2PIN of
CN11 on PCB3)
Remedy
Case 1 Below DC 18V
Replace PCB1.
Refer to section 1
4
.3.1.
Case 2 DC 18 a 25V
Replace SOL1.
Refer to section 1
4
.3.1.
PCB3
CN11
pin3
pin4
COMPONENT
TESTED
TERMINALS
ACCEPTABLE
VALUE
Positive
lead
Negative
lead
Diode of D1
3, 4, 5
0
0
3, 4, 5
0.3 to 0.5V
Open
Diode of D1
3, 4, 5
2
2
3, 4, 5
Open
0.3 to 0.5V
Thyristor of D1
0
1 1
0 Open
Open
Gate of D1 6 7 52 +3, ±3ohm
D1
5
67
4
3
2
1
0
0 6 7
1
2
5
4
3
13-14 June 30, 2008
TRANSTIG 300 AC/DC SERVICE MANUAL