Tweco 400 Ultra-Cut XT Plasma Cutting System - Manual (Page 212)

ULTRA-CUT 100 XT/200 XT/300 XT/400 XT
A-78 APPENDIX Manual 0-5297
a. Swap the ribbon cables of the inverter section 1A and 1B. If fault remains unchanged, still 237, problem
is with either ribbon cable or the CCM. If fault changes from 237 to 224 indicating inverter 1A missing,
then it’s the inverter that’s defective.
b. If the fault remained unchanged in step a., on the inverter end put the ribbon cables back in their original
positions. Now swap suspect ribbon cables on the CCM. If the fault now changes it’s the ribbon cable.
If it remains the same it is the CCM.
c. If there are 2 or more ribbon cables in addition to the one on section 1A then CCM is seeing none of them
connected which indicates the CCM is faulty.
238 System Bias voltage identification is invalid.
At power up the System Bias board measures the input voltage and sends signals to the CCM indicating which
range of voltage it has detected. See section 231-236 for details. If one of the 3 voltage ranges, 208-230V, 380-
415V or 480V isn’t identified then both ID signals are high resulting in an invalid signal.
Possible causes:
• Unit is connected to voltage below the 208-230V range or above the 480V range. (unlikely unless there is
a problem with the incoming voltage.)
• Defective System Bias board
• Bad connection between System Bias output J62 and CCM input J27 on the I/O board.
• Defective CCM
Troubleshooting:
1. Measure all 3 phases of the input voltage and confirm they are within the tolerance specified in the unit
manual.
2. Refer to section 231-236 Inverter VAC Mismatch and perform troubleshooting in step 1.b. If the 2 signals
don’t match the incoming voltage, if both are high, then the System Bias is defective.
3. If step 2 was OK make the same measurement at J27 on the CCM I/O PCB. If OK here the CCM is defective.
Otherwise inspect the connections at J62 and J27.
239 AC Voltage High
Voltage OK -- At power up the System Bias board measures the input voltage and determined if it is within the
range of voltage set by the J16 jumper. See section 231-236 Inverter VAC Mismatch Troubleshooting step 1.a
for details of the jumper. Normally when the input voltage is OK the System Bias board turns on a relay K1
on the left die of the board to apply power to the T1 Auxiliary transformer. D44, a green “Transformer ON”
LED, will light when K1 is energized. T1 provides power to the gas controls and the TSC 3000 as well as the
pumps and fans.
Voltage High -- If the AC voltage is determined to be too high it lights D4, ACV HIGH, a red LED on the System
Bias board, and sets the signal “AC V HIGH b” on J62-6 to a “high” about 24VDC (normal for a “low” here is
10-14VDC). To prevent the possibility of excessive voltage applied to several items (gas controls, pumps, fans
etc.) K1 is opened removing power from T1 and D44 goes off. If it’s more than a momentary glitch the gas
controls and the TSC 3000 (if used) will reset. Communication with the cutting table may be interrupted. With
the DFC 3000 Auto Gas Control and perhaps the cutting table control, the process will have to be reloaded.
D4 is on and the signal “AC V HIGH b” is high only while the voltage is actually high. The signal “AC V HIGH
b” does not latch on.
If the fault is E239 that means it is currently active, that is, currently detected as being too high. If it’s L239 that
means the voltage too high previously but it is not too high now. Applying START will clear the fault unless
it becomes active again.