Miller RAD-780 Mode D'emploi page 21

3-2. Brush Inspection And Replacement
1
Tools Needed:
3-3. Troubleshooting
Trouble
Electrode wire feeding stops or feeds
erratically during welding. erratically during welding.
Motor runs slowly.
Motor runs at full speed regardless of
wire speed setting.
Motor runs in reverse direction.
3/8 in (9.5 mm)
Minimum Length
Replace
Damaged
Brushes
3
2
Readjust hub tension and drive roll pressure.
Change to correct size drive roll.
Clean or replace dirty or worn drive roll.
Check and replace incorrect size or worn wire guides.
Replace contact tip or liner. See gun/torch Owner's Manual.
Remove weld spatter or foreign matter from around gun/torch nozzle opening.
Check and secure motor plug connection; check brushes.
Have Factory Authorized Service Agent check drive motor.
Reduce load. Decrease hub brake tension or drive roll tension.
Check for correct input voltage.
Check weld control unit for proper operation.
Switch locations of pins 1 and 3 in power cord as shown in Section 2-11.
3/4 in (19 mm)
New Length
Remedy
1 Brush Cap
2 Spring Clip
3 Brush
Remove brush cap. Remove spring
clip and brush.
Replace brush if it becomes chipped
or broken, or if less than 3/8 in (9.5
mm) of brush material is left.
Install brush so curved surface on
end of brush matches curve of motor.
Reinstall spring clip and cap.
Repeat procedure for other brush.
802 954-A / Ref. 802 269 / S-0816
OM-1598 Page 17