Lincoln Electric LN-8 SVM132-A Service Manual page 61

F-11
FIGURE F.1 – LN-8 ELECTRICAL SEQUENCE OF OPERATION (continued)
RELEASE
GUN TRIGGER
OPENS 2-8 (NOTE 1)
OPENS 2-4 CIRCUIT
DE-ENERGIZES
POWER SOURCE
PILOT RELAY
DE-ENERGIZES
POWER SOURCE
CONTACTOR
ELECTRODE IS
COLD TO WORK
NOTE 1: When interlock is open.
NOTE 2: When interlock is closed.
NOTE 3: 3 CR is not used on units with code no. 7926 and up.
TROUBLESHOOTING AND REPAIR
WELDING
DE-ENERGIZES 1 CR
OPENS 531-7
DISCONNECTS MOTOR ARMATURE
AND CONTROL CIRCUIT FROM
INPUT AC LINE - (DE-ENERGIZES
AUX. EQUIPMENT IF CONNECTED)
UNIT READY
FOR NEXT WELD
OPENS INTERLOCK
ON 1 CR (NOTE 2)
OPENS 683-32A CIRCUIT
REVERSES
MOTOR FIELD
DYNAMIC BRAKE
CURRENT FLOWS
THROUGH FREE
WHEELING DIODE (D-7 ON
CONTROL BOARD)
MOTOR STOPS
LN-8
BREAK
WELDING ARC
DE-ENERGIZES
2 CR
REED SWITCH
CLOSES 682-683
3CR (NOTE 3)
REED SWITCH
MOMENTARILY
CLOSES
DISCHARGES SLOW
ACCELERATION
CAPACITOR (C3 ON
CONTROL BOARD)
RESETS SLOW
ACCELERATION
CIRCUIT
F-11