Thermal Arc ARCMASTER 300 AC/DC, Service Manual

Page: 43 / 116

300ACDC
9
VOLTAGE REDUCTION DEVICE (VRD)
9 – 2
3
Switching VRD On/Off
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.
Figure 9-1: VRD ON/OFF Step A
B) Remove four mounting screws from the control
panel (see Figure 9-2).
Figure 9-2: VRD ON/OFF Step B,C
C) Access the VRD control by gently prying back
the front panel controls to reveal the VRD on/
off potentiometer (see Figure 9-3).
CAUTION
Do not pull back the front panel with excessive
force as this will unplug control PCB. Plugging the
control PCB back into the front panel controls can
only be achieved by removing the Side Panel.
Figure 9-3: VRD ON/OFF Step 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: rotat7e the trim potentiometer
(VR1) on the display PCB fully counter clock-
wise.
WARNING
The VRD ON/OFF trim potentiometer MUST ONLY
be positioned fully clockwise OR fully counter
clockwise as the VRD function will be unknown for
every other position.
1
3
2
1
1
1
1
2
VR1