Switching Vrd On/Off - Thermal Arc ARCMASTER 300S Service Manual

3
Sw i t chi ng VR D O n/ O f f
Switch the machine Off.
A) Remove the clear plastic cover from the control
panel (see Figure 9-1).
Lift up the cover so it rests on the top of the
unit.
Place a small flat bladed screw driver between
the cover hinge on the front panel.
Gently lift the cover hinge out of the front cover
mounting hole.
Remove the control's clear plastic cover.
2
Fi gur e9-1: VR D O N/ O FF St ep A
B) Remove four mounting screws from the control
panel (see Figure 9-2).
1
1
Fi gur e9-2: VRD O N / O FF St ep B , C
300/ 400TS and 300/ 400S
3
1
1
2
1
9 – 2
9
Vol t age R educt i on D evi ce ( VR D )
C) Access the VRD control by gently prying back
the front panel controls to reveal the VRD on/
off potentiometer (see Figure 9-3).
C A U TI O N
D o not pul l back t he f r ont panel w i t h excessi ve
f or ce as t hi s w i l l unpl ug the cont r ol PC B. Pl uggi ng
the cont r ol PC B back i nt o t he f r ont panel cont r ol s
can onl y be achi eved by r em ovi ng t he si de cover s.
Fi gur e9-3: VRD O N / O FF St ep D
D) Turning the VRD ON/OFF (see Figure 9-3).
To turn VRD ON: rotate the trim potentiometer
(VR1) on the display PCB fully clockwise.
When VRD is turned ON check that it operates
as per VRD Specifications on section 9.1.
To turn VRD OFF: rotate the trim potentiometer
(VR1) on the display PCB fully counter clock-
wise.
W A R N I N G
The VR D O N / O FF t r i m pot ent i om et er M U ST O N LY
be posi t i oned f ul l y cl ockw i se O R f ul l y count er
cl ockw i se as t he VR D f unct i on w i l l be unknow n f or
ever y ot her posi t i on.
VR1