A SERVICE OF

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-- 7 --cmek2de1
Sections1to11belowrefertothediagramonpage5.
The circuit board is screened by a m etal casing, connected to 0 V in the wire feed unit.
1 Power supply
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The feeder obtains a 42 V supply from the control power supply tr ansformer in the
power unit via contact XP01. Its power demand at maximum load is 3.5 A.
42 V AC is used for the welding torch trigger switch and as the power supply to the
gas solenoid valve and the main contactor. In addition, 42 V is also available on
contacts H01 and H02.
Rectifier BR1 rectifies the 42 V supply to 60 V. Capacitor C28 smooths the voltage,
which then supplies the wire feeder motor.
Transistor Q8 is a pre--regulator which reduces the voltage from 60 V to 20 V. Q8 is
current--limited to about 200 mA. If the 20 V supply drops below 13 V, the wire
feed unit stops.
VR1 and VR2 are 5 V and 15 V voltage regulators respectively.