Auxiliary Circuits - Lincoln Electric SVM 106-A Service Manual

CIRCUIT
TRIGGER
BREAKER
FORMER
FROM
115 VAC
WELDING
POWER
SUPPLY

AUXILIARY CIRCUITS

TIMER KITS
The optional GMA Timer and Burnback kits
can be added to provide time delays for
these functions. Both kits provide a burnback
control which maintains the welding power
source contacts closed for a short time after
the trigger is released. The timer kit also has
controls which can provide a gas preflow and
postflow by controlling the timing of the gas
solenoid. See Figure E.4.
NOTE: Unshaded areas of block logic diagrams are the subject of discussion.
THEORY OF OPERATION
FIGURE E.4 – AUXILIARY CIRCUITS.
OPTIONAL
METER KIT
8.8 VAC
TRANS-
DIODE
24 VAC
RECTIFIER
24 VDC
NETWORK
WIRE
SPEED
CONTROL
OPTIONAL
GAS
TIMER OR
SOLENOID
BURNBACK KIT
115 VAC
SCR CURRENT
POWER LIMITING
CIRCUIT CIRCUIT
115 VAC
CONTROL
BOARD
CR1
CONTROL
RELAY
GROUND
LEAD
PROTECTOR
METER KITS
The optional meter kit indicates the welding
voltage from the electrode to the work. This
voltage is measured from the contact block in
the wire drive compartment to the work.
While the analog meter kit does not require
any additional power, the digital meter kit is
powered by an 8.8 VAC signal from the
trigger transformer. See Figure E.4.
E-5
5-95 VDC
WIRE DRIVE
MOTOR
TO WELDING
CONTACTOR
GUN
TRIGGER
LN-7 GMA WIRE FEEDER