E-3
THEORY OF OPERATION
LN-10
E-3
INPUT RECEPTACLE, CONTROL
BOARD AND OPERATOR
CONTROLS
The 42 VAC input voltage is applied to the LN-10
through a 9-pin amphenol type receptacle. The
remote control and trigger leads are also accessed
through this 9-pin receptacle. The 42 VAC is rectified
by a full wave bridge and sent to the control board
where it is filtered. This filtered DC voltage is applied
to a switching power supply. The switching power
supply manufactures +12VDC and -12VDC regulated
supplies for the control board circuitry. A +5VDC reg-
ulated supply is also developed for the control board
circuitry.
The control board receives commands from the user
operated controls such as the volts encoder, the wire
feed speed (WFS) encoder and the keypad. It also
receives feedback information from the wire feed head
as to the wire feed speed and the arc voltage. The
control board compares the feedback information with
the user command signals and generates the appro-
priate signals to control wire feed speed, arc voltage
and gas flow.
The current sensing switch and ground lead protector
are connected to the control board via plug J1. The
current sensing reed switch closes when welding cur-
rent is established. This closure signals the control
board to change from the run-in welding parameters
to the preset welding wire feed speed and arc voltage.
If the ground lead protector is activated, the trigger cir-
cuit will be disabled and the WFS display will show
“GLP”.
FIGURE E.2 — LN-10 INPUT RECEPTACLE, CONTROL BOARD AND OPERATOR CONTROLS.
