Thermal Arc 185 AC, Service Manual

Page: 65 / 122

10-15
ARCMASTER 185 ACDC 200 ACDC
May 22, 2006
2. 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 at the beginning of an above section
“1. Preparation”. Refer to section 10.4.1.
1) Verify the voltage between the PIN 3 (Positive [+])
and PIN 4 (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 10-13. When you measure the above
voltage, do not remove the connector. Conduct
the measurement while the connector plug and
receptacle are still connected.
PCB3
CN11
Pin 3
Pin 4
Figure 10-13: Verification of the SOL1
2) Using the measurement taken above, follow the
chart below for possible failure modes.
3. Verification of the primary Diode (D1)
1) Verify the characteristic of the primary diode, D1,
using a diode tester.
2) Refer bellow Table 11-5 and Figure 11-14 for the
checkpoints on D1.
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
3, 4, 5
2
2
3, 4, 5
Open
0.3 to 0.5V
Thyristor of D1
0
1 1
0 Open
Open
Table 10-5: Tester checkpoints for D1
6
7
3
4
5
2
1
0
0 6 7
1
2
5
4
3
Figure 10-14: Tester checkpoints for D1 showing the
interconnection diagram
Voltage
measurement.
(1PIN-2PIN of
Remedy
CN11 on PCB3)
Case
1
Below DC 18V
Replace PCB1. Refer
to section 12.3.1.
Case
2
DC 18 ~ 25V
Replace SOL1. Refer
to section 12.3.25.
Table 10-4: 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).