Lincoln Electric LN-25 Service Manual page 37

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E-5 E-5
THEORY OF OPERATION
PROTECTIVE DEVICES AND
CIRCUITS
OVERVOLTAGE SHUTDOWN
If the power source open circuit voltage exceeds
about 110-120 volts, the LN-25™ will not operate until
the power source voltage drops below about 102-112
volts.
MOTOR OVERLOAD SHUTDOWN
If excessive motor overload occurs (due to prolonged
excessive feeding force, jammed drive rolls or shorted
motor leads) the LN-25™ will shut down within a few
seconds after the overload occurs. The shutdown will
reset automatically when the gun trigger is released,
but will reoccur if the overload situation is not remedied
CONTROL PC BOARD FUSES
On G1757-2 thru -5 part no. PC boards, the 1/8 amp
fuse interrupts the 500A lead to the trigger switch.
On G1757-1 PC boards, a 5 amp fuse was used to
interrupt the 667 lead. The LN-25™ will not operate
if either fuse is blown.
On G1757-6 (or higher) part no. PC boards, the 1/8
amp fuse was replaced with electronic protection for
trigger circuit faults to electrode circuit.
LN-25™