Logic & Control Problems - Thermal Arc Fabricator 140 Service Manual

FABRICATOR 140, 180
6.09 Logic & Control Problems
A. AC LED is on and the fan is on. Gas does not flow and
the feed roll does not turn when the MIG gun switch
is closed.
1. Defective MIG gun switch.
a. Check for continuity between P6-2 to P6-5
when the gun switch is closed.
b. If no continuity is found, the fault is in the MIG
gun.
2. Defective PCB.
a. Install a jumper between J5-7 to J5-8.
b. If gas does not flow and feed roll does not
turn, replace the PCB.
B. AC LED is on and the fan is on. When the MIG gun
switch is closed, gas does not flow but feed roll does
turn.
1. Gas supply problem.
a. Make sure the cylinder is not empty, the valve
is turned fully on and that the flow meter
regulator is adjusted properly and the supply
hose is attached to the unit.
2. Defective solenoid.
a. Replace the solenoid.
C. AC LED is on and the fan is on. When the MIG gun
switch is closed, gas flows, feed roll does not turn,
output voltage is measures 21 VDC.
1. Defective Wire Feed Motor M2.
a. Measure for DC Voltage on the PCB between
J5-1 to J5-2. If there is voltage present, replace
M2.
2. Defective PCB.
a. Measure for 21VDC on the PCB between
terminals J5-1 to J5-2. If voltage is present
with the MIG gun switch closed, replace the
PCB.
Manual 0-4992
ADVANCED TROUBLESHOOTING
D. AC LED is on and the fan is on. When the MIG gun
switch is closed, gas flows, the feed roll does not turn,
and the output voltage measures 0 VDC.
1. Defective VOLTAGE CONTROL SWITCH (SW1).
a. Check continuity - See truth table on system
schematic.
2. Defective T1 Transformer.
a. Measure the T1 secondary voltage between
terminals AC1 and AC2. See section 6.12 T1
Transformer Test.
3. Defective Rectifier.
a. Check diodes - See section 6.11 Rectifier
Assembly Test.
4. Defective Working Capacitors.
a. Check C1 & C2 - See section 6.13 C1& C2
Test Procedure.
6-4 January 25, 2008