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