TROUBLE SHOOTING
TS
M
40.1
© MOSA
1.0-04/04
PROBLEM
No welding current but
auxiliary output is OK
Weld poorly
Intermittently welds poorly
No welding output and
no auxiliary power
output
POSSIBLE CAUSE
1) Defective diode bridge
2) Problem with welding current control
(PCB)
1) Defective diode bridge
2) Problem with welding current control
(PCB)
1) Bad connections to welding current PCB
2) Problem with welding current control
PCB
1) Short circuit in wiring
2) Defective condenser
3) Defective stator
4) Short circuited diode bridge
WHAT TO DO
1) Check the diodes of the bridge
2) Is the remote control switch in the
internal position?
3) Check the diodes and SCR’s of the
bridge.
4) Check the transformer which supplies
power to the welding control PCB. If it
is OK replace the PCB
1) Check the open circuit welding
voltage.
If it is OK the diode bridge is OK. If it
is 1/3 or 2/3 of the nominal value
check the diodes or the SCR’s.
2) If the diode bridge is OK replace the
PCB.
1) Check that the pins of the green
connectors are clean and making
good contact.
Check that shunt connections are tight.
2) Replace the welding current control
PCB
1) Check the wiring inside the welder for
a short circuit between cables or to
ground.
2) If the wiring is OK, short circuit the
condenser to be sure that it is
discharged, disconnect all wires from
condenser and, using an ohmmeter,
check that the condenser is not short
circuited.
3) If the condenser box is OK,
disconnect all leads from the stator
except for those going to the
condenser box and check the
output from the alternator.
If there is no output from the welding
winding and the auxiliary winding,
replace the stator.
4) If there is output from all windings
reconnect the diode bridge and check
if there is welding current. If not the
diode bridge is defective. If there is
welding current connect the auxiliary
power leads one at a time until there
is no output; at this point, the short
circuit is in that line.
only for models with electronic control of welding current.
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06/04/04 M40-1-I
