Tweco 400 MST Arc Master - Manual (Page 47)

400MST
9
ADVANCED TROUBLESHOOTING
9 – 10
 Confirm the connections of the required
cables; control cable for the wire feeder
equipment, cable for welding, and a cable for
the base metal are all secured.
 Confirm that there are no connection errors
or broken wires of the required cables; con-
trol cable for the wire feeder equipment, cable
for welding, and a cable for the base metal.
d) Verify the no-load voltage (OCV). *Applies to
STICK and MIG mode.
 Refer to section "Verification of No-Load volt-
age (OCV)" in the section 9.1.4.8 first
before continuing this section.
 If performing the "No-Load Voltage Failure"
procedure does not rectify the failure, per-
form the following tests in the sequence
below. Replace any defective components
found.
1) Diode, D2, D3, D4 and D5. (Refer to the
Section 9.1.4.6)
2) Reactor, FCH. Confirm the connection of
FCH and PCB14 (WK-5594). (Refer to the
Section Appendix 3)
3) PCB8, PCB9, PCB10, PCB11 (WK-5479).
(Refer to the Section 9.2.4.7 and 9.2.48)
4) Hall CT, HCT1. Confirm the connection of
FCT1 and PCB6 (WK-5688). (Refer to the
Section 9.2.4.22)
e) Verify the wire feeder equipment, and replace
it if necessary.
 Refer to the operating manual supplied by the
wire feeder manufacture before any work is
performed on the wire feeder.
1.3.4 "Operating Panel Failure" (LED's
do not light properly or weld set-
tings cannot be established.)
Cause
Occurs when there is a connection failure among
PCB3 (WK-5548), PCB6 (WK-5688) and PCB12
(WK-5527) or PCB3, PCB6 and PCB12 are defec-
tive.
Verification/Remedy
a) Verify the PCB connection between CN21 on
PCB6 (WK-5688) and CN2 on PCB12 (WK-
5527).
 Confirm a secure connection of the harness
and the connections between CN21 on PCB6
and CN2 on PCB12.
 Contact the manufacturer if you find any broken
connectors or damaged wiring harnesses.
b) Verify the connection between PCB5 (WK-
5696) and PCB6 (WK-5688).
 Confirm that all three connectors between
PCB5 and PCB6 are tightly connected.
 Confirm the condition of the pins on the con-
nectors and the connectors themselves. If
bent pins or damaged connectors are found,
replace the suspected PCB.
 Refer to section 9.2.4.5 and 9.2.4.6 for the
replacement and installation of PCB5 and
PCB6.
c) Replacement of PCB6 (WK-5688) and PCB12
(WK-5527).
 Refer to section 9.2.4.6 for the replacement
and installation of PCB6 and section 9.2.4.9
for PCB12.
1.4 Fault Isolation Tests
1.4.1 Preparation
The following initial conditions must be met prior to
starting any of the procedures in this section
(9.1.4).
1) Connect the appropriate input voltage. (Check
the name plate on the rear of the power supply for
the proper input voltage.)
NOTE
Operate at ALL input voltages as noted on the
nameplate on the rear panel when testing the
power supply.
2) Close primary power source wall disconnect
switch or circuit breaker.
3) Place power supply MAIN CIRCUIT SWITCH
(S1) on rear of unit in the ON position.
WARNING
Dangerous voltage and power levels are present
inside this unit. Be sure the operator is equipped
with proper gloves, clothing and eye and ear pro-
tection. Make sure no part of the operator's body
comes into contact with the workpiece or any inter-
nal components while the unit is activated.