TM-944 Page 20
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SECTION 6 − TROUBLESHOOTING
6-1.
Troubleshooting Table
.
See Section 6-2 or 6-3 for test points and values
and Section 9 for parts location.
Trouble
Remedy
No weld output; wire does not feed; fan
does not run.
Secure power cord plug PLG1 in receptacle (see Section 3-6 or 3-7).
Replace building line fuse or reset circuit breaker if open.
Place Power switch S1 in On position (see Section 4-1).
Reset power source circuit breaker if open (see Section 7-2).
No weld output; wire does not feed; fan
runs.
Rotate Voltage switch S2 out of the Purge (gas only) position.
runs.
Thermostat TP1 open (overheating). Allow fan to run; the thermostat will close when the unit has
cooled (see Section 7-3).
Secure gun trigger leads to receptacle RC3 (see Section 3-1).
Check continuity of gun trigger leads. Repair or replace gun if necessary.
Check Wire Speed control R1 for proper connections and resistance; R1 is 55k ohms
±
20%.
Replace R1 if necessary.
Check continuity of Voltage switch S2, and replace if necessary.
Check diodes in main rectifier SR1, and replace if necessary.
Check main transformer T1 for signs of winding failure. Check continuity across windings and check for
proper connections. Check secondary voltages. Replace T1 if necessary.
Check control board PC1 connections and voltages, and replace if necessary.
Check the setting of Voltage switch S2. Machine will not weld if voltage control is set between range
positions. Rotate switch until it “clicks” into a detent position.
Electrode wire feeding stops during
welding.
Straighten gun cable and/or replace damaged parts (see Section 7-6).
Readjust drive roll pressure (see Section 3-10).
Change to proper groove (see Section 7-4).
Readjust wire reel hub tension (see Section 3-9).
Replace contact tip if blocked (see Section 7-5).
Clean or replace wire inlet guide or liner if dirty or plugged (see Section 7-4 and/or 7-6).
Replace drive roll or pressure bearing if worn or slipping (see Section 7-4).
Secure gun trigger leads in receptacle RC3 (see Section 3-1).
Check continuity of gun trigger leads. Repair or replace gun if necessary.
Check and clear any restrictions at drive assembly and liner (see Section 3-10 and/or 7-6).
Release gun trigger and allow gun and motor protection circuitry to reset.
Check T1 for signs of winding failure. Check continuity across each winding and check for proper
connections. Check secondary voltages. Replace T1 if necessary.
Check Control board PC1 and connections, and replace PC1 if necessary (see Section 6-4).
