Buffalo Tools MMIG125, Assembly & Operating Instructions

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A SHORTED nozzle results when spatter
buildup bridges the insulation in the nozzle,
allowing welding current to flow through it as
well as the contact tip. When shorted, a noz-
zle will steal welding current from the wire
whenever it contacts the grounded work
piece. This causes erratic welds and reduced
penetration. In addition, a shorted nozzle
overheats the end of the torch, which can
DAMAGE the front-end of the torch.
A RESTRICTED nozzle is created when
enough slag builds up in the nozzle to affect
the direction, concentration, and/or rate of
the shielding gas flow. This problem can
cause porous, brittle welds and reduce
penetration.
TESTING FOR A SHORTED NOZZLE
Arcing between the nozzle and the work
piece ALWAYS means the nozzle is shorted,
but this can be hard to detect through the
lens of a welding helmet. The following test-
ing method is another way to tell if a nozzle
is shorted.
With the welder unplugged from the ac
power source, touch the probes of an ohm-
meter or continuity tester to the end of the
contact tip and the outside of the nozzle. If
there is any continuity at all, the nozzle IS
shorted. Clean or replace as needed.
REPLACE A TORCH LINER
When installing a new torch liner, care must
be taken not to kink or otherwise damage the
torch liner. See Figure 21 for the drive
assembly and Figure 22 for the torch
assembly.
1. Turn OFF welder POWER SWITCH and
unplug welder from power supply.
2. Open the welder side panel.
3. Loosen the tension arm and lift it up off
the drive roller.
4. Turn the wire spool counter-clockwise (be
sure to hold onto the wire itself while turn-
ing the spool or the wire will unspool itself
when it becomes free of the torch liner),
and remove wire from the welder.
5. Lay torch cable and torch handle straight
out in front of unit.
6. Remove torch Strain Relief Clamp by
removing the four screws.
7. Take torch handle halves apart by
removing four phillips head screws.
8. Remove the hanging hook from the two
case halves by carefully pulling it apart
until it is free from the torch.
9. Remove liner from gas block by pulling it
from the bottom of the gas block, being
careful not to separate gas block halves.
10. Remove liner from outer torch sleeve by
pulling from torch end.
11. Install new liner, starting from torch end
and feeding towards unit.
12. Push the new liner back through gas
block and into the neck of the torch until it
is fully seated then push into the groove
at the rear or base of the block.
13. Return all components to the handle
casing and realign them as they were
originally.
Tech Tip: Be sure all o-ring’s have been
returned to their original positions.
14. Fit liner for length at feeder end by cutting
liner with wire cutters.
15. Reinstall liner holding clamp at feeder.
16. With both halves of the handle case in
place, tighten the four phillips head
screws.
17. Replace hanging hook.
18. Reinstall the welding wire according to
specifications in INSTALL THE WELDING
WIRE section.
19. Close side panel.
20. Plug welder into power supply and turn
POWER SWITCH to ON position.
PREVENTIVE MAINTENANCE
Except for internal and external cleaning,
cleaning the nozzle, and occasionally retight-
ening screws, there is no periodic mainte-
nance recommended for your welder.
TROUBLESHOOTING
The following TROUBLESHOOTING informa-
tion is provided as a guide to help resolve
some of the more common problems that
could be encountered. Table 5 is a trou-
bleshooting table provided to help you deter-
mine a possible remedy when you are having
a problem with your welder. This table does
not provide all possible solutions, only those
possibilities considered to likely be common
faults. The table consists of a TROUBLE or
symptom, a POSSIBLE CAUSE for the
symptom, and a POSSIBLE REMEDY for
that symptom.
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