Tweco 400 XT Ultra-Cut Plasma Cutting System - Manual (Page 159)

ULTRA-CUT 400 XT
Manual 0-5275 APPENDIX A-51
1. The Pilot board is behind the CCM in the AC 300 XT and all Ultra-Cut XTs or on the upper section of the second inverter
module in an AC 200 XT and has two LEDs. The first one, D11, a green LED, indicates the board has bias power and
should be on all the time when the unit is turned on. The second LED, D2, also green, is on when the pilot is enabled, that
is the pilot IGBT switch is turned on. The pilot is enabled near the end of preflow time and remains on until the transfer
is established or for 15 seconds after which a 102 code is displayed. If D2 performs as expected you know the CCM,
Relay board and work current sensor are not causing the problem.
2. If D11 on the Pilot board is not on check if the 10 pin ribbon cable is connected between the Pilot board (J�2) and the
Relay board (J3). Measure for 2� VDC on the Pilot ribbon cable test connector pin 2 (+) and pin 10 (-). If 2�V is present
and neither D11 nor D2 lights then the Pilot board may be defective. Pilot board end of the ribbon cable could also be
the cause.
What should happen on the Relay board is LEDs D12, work Current Detected & D11, Pilot Current Detected should both be
off. When you apply START after 2 seconds (Preflow time) D7, Pilot Enable, should come on. Also D23, RF ON, should
come on indicating the Arc Starter is being enabled. Normally D23 would only be on for a moment until pilot current
is detected. Then D11 would be on (and D23 off) until arc transfer or pilot timeout (15 sec.) Since a pilot has not been
detected D11 should not come on.
3. If the work current sensor is defective it could be telling the relay board (and thus the CCM) that there is already a trans-
ferred arc so no need for pilot. D12, a green LED on the Relay board, is on if work current is detected. If D12 is not on
skip to step 5, otherwise disconnect J1, the work sensor connector. If D12 is still on the Relay board is defective.
�. If D12 goes out when J1 is disconnected, plug it back in and measure voltage from TP1 (common) to J1-1, should be
positive 12-15VDC. Now measure J1-2, should be negative 12-15VDC. Now measure J1-3, should be 0 +/- 0.05V. If
any of these are wrong disconnect J1 and measure again (on the relay board, not the harness). If still wrong the relay
board is defective. Otherwise it’s the work sensor.
5. Pilot Enable signal comes from the CCM on pin 15 of the �0 pin ribbon cable between the Relay board (J�) and the CCM
(J23). It should be low, less than 2V relative to TP1 on either the CCM I/O board or the Relay board. You can also measure
this on TP11 of the I/O board. If the signal does not go low when the pilot should be enabled at the end of preflow time
then the CCM is probably defective. You can also jumper TP11 on the CCM I/O board to TP1, also on the I/O, to see if
that will light D7, the Pilot Enable LED, on the Relay board. If it does, that further confirms the CCM is bad. If jumping
TP11 to TP1 does not light D7 on the Relay board, the problem is likely the Relay board or possibly the ribbon cable.
103 Lost Pilot
Code 103 occurs when Pilot has ignited as sensed by the pilot current sensor on the Pilot board , but went out on its own
while CNC Start is still active before the pilot timeout (�5 ms. or 3 sec.).
Possible causes:
• Preflow gas pressure too high, for manual gas controls check cut charts for proper setting. For DFC 3000 check that
the process is correct for the consumables.
• Cutting current set too low for the torch parts being used. Pilot current level is automatically set based on the cutting
current. A low cutting current results in a lower pilot current that may not be able to sustain a pilot for higher current
torch parts.
• Remote Analog Current Control switches set wrong can also result in lower than normal pilot current setting. See
section on these switch settings under next section for code 10�.
• Broken torch pilot wire.
• Defective Inverter module puts out less current than it’s set for.