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Problem:

• Welding process starts but welding current is not constant. Finally the welding wire breaks.

Possible Causes & Resolutions:

• Bad condition of the lower welding roller or upper roller head. In this case, the current only flows through the welding wire and no longer over the welding roller or upper roller head. The welding wire heats up and breaks. Exchange lower welding roller. If the problem still exists, replace the upper roller head.

Problem:

• Welding process starts but no welding current.

Possible Causes & Resolutions:

• Condition of lower welding roll: Possibly the roll is worn out or mercury very old. Refill mercury or exchange lower welding roll.
• Condition of upper roller head: Possibly the roller head is worn out or mercury very old. Refill mercury or exchange upper roller head.
• Waterflow: The green button for welding current on/off must light up when the water flow is ok. If not maybe the water flow is to low. Check also the relay K21. If water flow is ok this relay has to be on.
• Welding pressure switch S31: If welding rolls are closed the switch S31 do enable the welding current. If the welding pressure is adjusted to low or also to high the control do not enable the current. Do adjust the welding pressure correctly according manual.
• All connections of current conductors on secondary side of welding transformer: All screws must be tightened. If there are signs of corrosion, disassemble parts and clean the contact surfaces.
• Connection between head piece and lower welding arm: Remove the head piece and check the contact surfaces.

• Fine-wire fuses F2, F3 and F4: This are located inside control. Check them with ohm meter and replace if necessary.
• Transformer T4 (18-0-18V): Measure the outputs of small transformer inside control. The easiest way to do this is to measure it at the terminals of the WEC card. c32/c30 => 18VAC, c32/c28 => 18VAC, c28/c30 => 36VAC
• WEC electronic card: Firmly inserted in the card holder?
• Thyristor: Maybe thyristor module is broken.

Problem:

• Welding process does not start or starts too early before the welding rollers are closed and burns a hole in the can.

Possible Cause:

• Wrong signal of welding pressure switch. The start of welding current and transport is activated by a digital pressure switch S31 installed on the air regulator for welding pressure. If the welding rolls close and the digital pressure switch reach the programmed value the welding does start.

Check:

• Is the setting of welding pressure correct?
• Does the welding pressure cylinder work fine? Does it open and close smoothly?
• Does the welding pressure switch work properly? The switch must switch on when the welding pressure is between 1.5 and 3.0 bar.