7 Inverter frequency is
abnormal
A
B
Control PCB is malfunctioning and
snubber circuit components for
secondary diodes on Inverter PCB
have failed open circuit, Check
components:
C1, R74, R1, R2, R3, R83
C15, R75, R20, R21, R23, R30
Check that Mains Supply Voltage is
greater than 276VAC.
A
B
Replace Control PCB and
replace defective components.
Disconnect the machine from
the Mains Supply Voltage
because input voltages greater
than 276VAC will cause
component failures with this
machine.
8 Excessive welding
current is supplied to
the welding arc, i.e.
welding current can’t
be controlled by the
Amperage Control on
front panel
A No DC current feedback signal on JP1
pins 14 & 7 from the Control PCB.
If no signal then check Current
Transformer, M1, on the primary tap
of the main transformer, D16, D17,
D18, D19, R59, R60, R61 and ribbon
cable between PCBs.
A Replace defective components.
If no defective components
then replace the Control PCB.
Table 11-2
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