| TROUBLESHOOTING |
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| Observe all Safety Guidelines detailed througout this manual | ||||
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| PROBLEMS |
| POSSIBLE CAUSE |
| RECOMMENDED |
| (SYMPTOMS) |
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| COURSE OF ACTION | |
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| FUNCTION PROBLEMS |
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C. Machine input contactor closes | 1. | Electrode or work lead loose or | 1. | Repair connections. | |
but has no or low output. Open |
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circuit voltage should be 67 to 71 |
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volts. | 2. | Open transformer primary or | 2. | Repair. | |
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| secondary circuit. |
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| 3. | Supply line fuse blown. | 3. | Replace blown fuse – check fuse |
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| size. |
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| 4. | Input line grounded causing | 4. | Repair input to machine. |
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| single phase input. |
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| 5. | Input leads not connected to | 5. | Connect input lead. |
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| contactor. |
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| 6. | Latching resistor, R3, open. | 6. a. Replace. | |
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| b. Check leads to the resistor |
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| and repair if defective. |
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| 7. | Control circuit problems. | 7. | See Troubleshooting Procedures |
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| – Power Silicon Controlled |
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| Rectifier. |
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D. Machine has maximum output | 1. | Possible defective power SCR. | 1. | Remove all gate leads G1, G2 | |
but no control. |
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| and G3 at PC board.* If welder | |
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| has any open circuit voltage, |
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| power SCR is defective. Check |
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| per Troubleshooting Procedures. |
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| 2. | Possible defective control board. | 2. | Replace. See Troubleshooting |
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| Procedures – Replacing PC |
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| Boards. |
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| * | Connector J4 on latest control |
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| board. |
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CAUTION
If for any reason you do not understand the test procedures or are unable to perform the tests/repairs safely, contact your Local Authorized Field Service Facility for technical troubleshooting assistance before you proceed.
E500