Thermal Arc ARCMASTER 300 AC/DC, Service Manual

Page: 53 / 116

300ACDC
11
ADVANCED TROUBLESHOOTING
11 – 8
3.2 "Gas Valve Failure" (No Gas
flow through unit)
Cause
Occurs when the gas valve (SOL1) is defective,
damaged or the driving voltage is incorrect.
Verification/Remedy
a) Confirm that TIG welding is selected on the
welding mode.

Do not change welding modes while welding.
Only change welding modes when the unit is
idle (torch switch OFF).

Verify the setting of Pre-flow and Post-flow
on the front panel. If the Pre-flow or Post-flow
time is set to 0 seconds, change them to
higher setting.
b) Verify the layout of the gas hose.

Confirm that the hose is securely connected
into the fitting at the inlet and the outlet. Con-
firm that the layout of the gas hose so that it
is not bent or kinked. Confirm there are no
breaks, burns or holes in the hose.

Confirm the layout of the TIG torch gas hose
and that the hose adapters are properly con-
nected.
c) Verify the wiring harness and connection of
gas valve (SOL1) and CN11 on PCB3
(WK-5548).
d) Verify the drive circuitry of the gas valve
(SOL1).

Verify the drive circuitry of the gas valve
(SOL1).

Refer to section 11.5.4.

Replace PCB3, when abnormal.

Refer to section 12.3.3.
e) Replace the PCB6 (WK-5549).

Refer to section 12.3.6.
3.3 "No Weld Output"
When in High Frequency TIG (HF TIG) mode, if the
High Frequency is not generated (present), refer to
"High Frequency Output Failure". Refer to section
11.3.5.
Cause
Occurs when the remote connector (CON1) or
associated circuitry is defective, damaged, or the
TIG torch cable is defective.
Verification/Remedy
Caution
Read and understand this entire section before
proceeding. Extreme personal harm and test
equipment damage will occur if the procedures are
not performed accurately.
a) Verify the remote connector (CON1).
(Applies to LIFT TIG and High Frequency TIG
(HF TIG) mode.)

Confirm a secure between the remote con-
nector (CON1) and the TIG torch cable.

Confirm a secure connection of the harness
and the connections between the remote
connector (CON1) and PCB7 (WK-5550) are
all correct and there are no open circuits.

Contact the manufacture if you find any bro-
ken connectors or damaged wiring har-
nesses.

Confirm the proper pins-outs of the remote
connector at the TIG Torch side. (Refer to
the Operating Manual.)

Confirm that there is no open circuit on the
remote connector at TIG Torch side.

In equipment for remote control use, confirm
the pin specification of a connector. (Refer to
section Operating Manual.)
b) Verify the condition and connections of the
welding cable, the stick rod holders and the
ground clamp. (Applies to all welding modes.)

Confirm a secure connection of the welding
cable, stick rod holders, ground clamp and
dinse connectors and there are no open cir-
cuits.