Tweco 400 MST Arc Master - Manual (Page 35)

400MST
7
Voltage Reduction Device (VRD)
7 – 2
d. Turning the VRD ON/OFF (see Figure 7-3).
 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 page 7-1.
 To turn VRD OFF: rotate 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.
Figure 7-3: VRD ON/OFF Step D