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TOC
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| MAINTENANCE | ||||||||||
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SAFETY PRECAUTIONS |
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| 1. Be sure the nozzle insulator is fully screwed onto the | ||||||||
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| gun tube and does not block the gas holes in the dif- | |||
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| WARNING |
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| fuser. |
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| • Have a qualified electrician do the | 2. Slip the appropriate gas nozzle onto the nozzle insu- | ||||||||
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| lator. Either a standard .50" (12.7 mm) or optional | ||||||||
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| maintenance | and | troubleshooting |
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| .62" (15.9 mm) I.D. | ||||||||
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| work. |
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| and should be selected based on the welding appli- | ||||
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| • Disconnect | the input power off |
| cation. |
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| Adjust the gas nozzle as appropriate | for the | |||||||
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| using the disconnect switch at the |
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| GMAW process to be used. Typically, the con- | ||||||||
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| main input supply before working |
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| tact tip end should be flush to .12" (3.2 mm) | ||||||||
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| inside machine. |
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| extended for the | |||||
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• Unplug the power cable if it is connected to a |
| and .12" (3.2 mm) recessed for spray transfer. | ||||||||||
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| receptacle. |
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| GUN TUBES AND NOZZLES |
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GENERAL MAINTENANCE |
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| a. Replace worn contact tips as required. |
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In extremely dusty locations, dirt may clog the air | b. Remove spatter from inside of gas | |||||||||||
passages causing the welder to run hot. Blow dirt out | ||||||||||||
| tip after each 10 minutes of arc time or as required. | |||||||||||
of the welder with |
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to eliminate excessive dirt and dust | GUN CABLE CLEANING |
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parts. |
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| To help prevent feeding problems, clean cable liner | ||||||||
The fan motors have sealed ball | bearings | which | ||||||||||
after using approximately 300 pounds (136 kg) of elec- | ||||||||||||
require no service. |
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| trode. Remove the cable from the wire feeder and lay | |||||||
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| it out straight on the floor. Remove the contact tip from | ||||
DRIVE ROLLS AND GUIDE PLATES |
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| the gun. Using an air hose and only partial pressure, | |||||||||
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| gently blow out the cable liner from the gas diffuser | ||||||||||
After every coil of wire, inspect | the wire | drive | end. |
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mechanism. Clean it as necessary by blowing with low |
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pressure compressed air. Do not | use solvents for |
| CAUTION |
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cleaning the idle roll because it may wash the lubricant |
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out of the bearing. |
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All drive rolls are stamped with the wire sizes they will feed. If a wire size other than that stamped on the roll is used, the drive roll must be changed.
For instructions on replacing or changing drive roll, see "Wire Drive Rolls" in Operation section.
CONTACT TIP AND GAS NOZZLE INSTALLATION
a.Choose the correct size contact tip for the electrode being used (wire size is stenciled on the side of the contact tip) and screw it snugly into the gas diffuser.
b.Screw the appropriate fixed gas nozzle fully onto the diffuser. Either the standard .50" (12.7 mm) flush nozzle or other optional flush or recessed (spray arc) nozzle sizes may be used. (See Table D.2 in this section.)
c.If using optional adjustable
Excessive pressure at the start may cause the dirt to form a plug.
Flex the cable over its entire length and again blow out the cable. Repeat this procedure until no further dirt comes out. If this has been done and feed problems are experienced, try liner replacement, and refer to trouble shooting section on rough wire feeding.
LINER REMOVAL AND REPLACEMENT
NOTE: Changing the liner for a different wire size requires replacement of the gas diffuser per Table D.1 to properly secure the different liner.
POWER MIG 255C
