Tweco 190 MIG Thermal Arc Fabricator - Manual (Page 37)

FABRICATOR 190 WELDING MACHINE
Manual No. 0-4838 4-1 OPERATION
SECTION 4:
OPERATION
4.01 Inside Panel
1. Burnback Control Knob: Burnback time is the difference between the wirefeed motor stopping and switching off of
the welding current. The Burnback time allows the electrode wire to burn out of the molten metal weld pool. The
Burnback time is factory set for optimum performance. Turn the Burnback knob clockwise to increase the time and
counter-clockwise to decrease it. The adjustable range is 0 to .6 seconds. Refer to Figure 4-1.
2. Wirefeeder Drive Roller Pressure Adjustment: The idler roll applies pressure to the drive roll via screw adjustable
spring pressure. The pressure adjust device should be adjusted to a minimum pressure that will provide satisfactory
wire feed without slippage. If slipping occurs, and inspection of the wire contact tip reveals no wear, distortion or
burn-back jam, the conduit liner should be checked for kinks and clogging by metal flakes and slag. If this is not
the cause of slipping, the feedroll pressure can be increased by rotating the pressure adjust device clockwise. The
use of excessive pressure may cause rapid wear of the feed roll, motor shaft and motor bearings.
3. Wire Reel Brake: The spool hub incorporates a friction brake which is adjusted during manufacture for optimum
braking. If it is considered necessary, adjustment can be made by turning the large nut inside the open end of the
spool hub. Clockwise rotation will tighten the brake. Correct adjustment will result in the spool circumference
continuing no further than ¾” (20mm) after release of the Gun trigger switch. The wire should be slack without
becoming dislodged from the spool.
Art # A-07397
Wire Spool Brake Drive Roller Pressure Adjustment
Figure 4-1: Inside Panel
!
WARNING
The electrode wire will be at welding voltage potential while it is being fed through the system.
CAUTION
Excessive tension on the brake will
cause rapid wear of mechanical wire
feed parts, overheating of electrical
components and possibly an
increased incidence of wire Burnback
into the contact tip.