the arc is broken. Time is variable from 1 to 30
(17) PRE-FLOW TIMER control. This variable
seconds.
control is on top of the timer (fig. 2-5) and controls
(19) SPOT ARC TIMER control. This control,
the length of time that gas and water flows before
located on top of the timer (fig. 2-5), varies the time
the arc can be struck. Time is variable from 1 to 30
that the timer allows the arc to be on. It is function-
seconds.
al only when the SPOT ARC switch is not in the OFF
(18) POST-FLOW TIMER control. This control,
position (para 3-16b).
located on top of the timer (fig. 2-5) varies the length
of time that shielding gas and water will flow after
Section IV. OPERATION UNDER USUAL CONDITIONS
gas shielded tungsten arc welding. The ma-
inert
2-9. General
chine has a RANGE SWITCH which provides opti-
This section contains step-by-step procedures for
mum amperage for light and heavy work. The WELD
various types of operation. Each type of operation,
AMPERES control on the front panel adjusts the
including starting and stopping the welding machine,
output within each range. A foot-operated remote
is described. Since each job may present a different
control can also adjust the output current within
problem, the operator may have to vary given pro-
each range. For choice of the welding output current
cedures to fit the individual job.
preferred in each welding job the machine has a
POLARITY SWITCH. The normal position of this
switch is determined by the work being done.
a. Preparation for Starting.
b. Timer Control System. The timer control sys-
(1) Perform the daily preventive maintenance
tem of this welding machine provides any combina-
services program described in paragraph 3-5.
tion of four different timer functions, although this
(2) Clean area on item to be welded to insure a
specific machine includes only three of the timers.
good connection.
The optional HIGH FREQUENCY dropout timer is
(3) Connect the cables to the welder electrode
not provided. Instantaneous high frequency dropout
and ground terminals (fig. 2-6) and connect the
is provided as standard with this welding machine
ground clamp of the ground cable to the work table
even though no timer is used. The white dummy
or item to be welded.
plug must be in the high frequency timer socket and
Caution: Do not operate the current range
the high frequency dropout switch set on START-
switch or the AC/DC selector and polarity switch
ONLY in order to obtain this function. The plug-in
under load. Arcing caused by opening the switch
timers govern the timing of the following functions:
carrying high current will severely burn the con-
post-flow of gas and water; pre-flow of inert gas; and
tact surface of these switches. This burning of the
spot arc timing. The timers are in a drawer at the top
contact surfaces will decrease the maximum cur-
of the welding machine, along with the high fre-
rent carrying capacity of the switches and possibly
quency section. The drawer opens to obtain access
cause the switches to become inoperative.
to the timer controls for adjustment or maintenance
b. Starting. Refer to figure 2-7 and start the weld-
by unlocking the key lock and tilting the front of the
ing machine.
drawer. An interlock switch opens the main contac-
Note. If a sustained overload or power failure occurs, the
tor K8, removing power to main transformer T1
welding machine shuts off. The POWER switch must be placed in
when the drawer is opened. The entire drawer sec-
ON position again to restore to standby condition.
tion can be unplugged and removed for servicing.
The drawer is secured with six screws behind the
drawer panel.
a. Refer to figure 2-8 and stop the welding ma-
c. Setting Timers. Before starting a new welding
chine.
procedure, the operator must decide which control
b. Perform the after operation services (table 3-1).
timers are to be used. A dummy plug must be in
each timer receptacle if the timer is not installed.
If dummy plugs are removed to insert a timer, save
a. General. The welding machine is designed for
plugs for future use. The PRE-FLOW TIMER and
use in coated electrode metallic arc welding and in
