Tweco 400 Ultra-Cut(May 2014) - Manual (Page 197)

ULTRA-CUT 100 XT/200 XT/300 XT/400 XT
Manual 0-5302 APPENDIX A-69
1. 208 code before START applied:
• Defective Pilot board (current sensor circuit).
• Defective Relay PCB
• Defective CCM
Pilot PCB
Pilot current signal is on the 10 pin ribbon cable (Pilot J42, Relay PCB J3) between pins 8 (-) and 9 (+). With no current, the
signal should be zero +/- 0.05 V. Also the Relay board has an LED, D11, “Pilot Current Detected”, which will light if the pilot
current signal exceeds 0.15V. If the signal is not zero V.Pilot PCB is likely the cause. To be sure, disconnect the Pilot board
ribbon cable from the Relay board at J3. If D11 goes out, the Pilot board was the cause. Double check by measuring pin 8 &
9 again. If it’s zero V. now, the Pilot board is defective. If D11 is still on or pin 8 & 9 voltage still high check the Relay board.
Relay Board or CCM
If D11 on the Relay PCB is still on after the previous tests, measure the output to the CCM on the 40 pin ribbon cable (Relay
J4 to CCM J23) between pins 23 (-) and 25 (+). It should be less than 0.1V. If not, the Relay board is bad. If voltage is zero
then the CCM is defective.
2. 208 code comes on during preflow:
IM#1 and the Pilot board are enabled near the end of preflow. To have unwanted current there must be a path (short) for
current to flow between the inverter negative output (negative cable/torch electrode) and the Pilot return/tip before the arc
starter is enabled for pilot ignition.
Possible causes are:
• Short between electrode and tip due to mismatch of consumables, damaged consumables or foreign matter between
tip and electrode. An electrode at the end of its life may lose material that can short between electrode and tip.
• Defective or incorrectly installed user supplied equipment such as torch height controls that make connections to
power supply output.
• Short between power supply negative output cable and pilot cable.
• Shorted torch body.
Troubleshooting:
1. Remove and insulate (may have voltage on it) the pilot cable from the rear of the unit. Attempt to pilot. If no 208 code
shows, it confirms problem is outside the power supply.
2. Remove and check consumable for damage, cleanliness and missing (gas dist, etc.) or wrong components.
3. Disconnect user supplied equipment and see if fault still exists.
4. Inspect Arc Starter for broken/disconnected wires or burnt components.
5. Inspect inside the torch mounting tube for shorts.
6. If all else fails disconnect the pilot wire from the back of the torch head. Insulate it well or keep it away from any metal,
it may have HF (high frequency) on it when you try to start. Try to start, if the 208 is gone now the torch head is shorted.
209 Not used. Reserved codes from the earlier product.
210–211 Output current, measured by the work lead current sensor, is too high (210) or too low (211).
These are warnings and do not shut down the process but may explain poor cut quality or poor parts life.
Individual inverter sections have their own current sensors and the work lead has a current sensor whose signal should equal
the sum of the individual inverter sections. Each section is set to output a certain current based on its ”demand” signal. If
the current differs from the total “demand”, sum of the individual demands, the individual sections are checked to determine
if their output is correct compared with their demand signals.
If the individual sections are correct but the work current sensor signal differs from the total demand by more than 16% code
210 (too high) or 211 (too low) is displayed.