Thermal Dynamics Ultra-Cut 300 XT, Operating Instructions Manual

Page: 166 / 214

ULTRA-CUT 400 XT
A-52 APPENDIX Manual 0-5275
Reasons why RAS Control relay would not close:
6. Pilot current flowing. There actually is pilot current flowing somewhere. Unlikely as it would normally set
the 208 fault but we have to rule it out.
a. Disconnect J41 on the Pilot board, if HF still doesn’t fire and the Relay board Pilot LED, D11, is still
on, it’s due to a fault in the detection circuits.
7. Faulty detection circuit. There isn’t any pilot current but a fault in the circuits measuring pilot current is
indicating there is current.
a. Measure between pins 8 (-) and 9 (+) on the Pilot ribbon cable from Relay board J3 to Pilot board J42. If
there is no pilot current it should be zero. Anything else indicates the Pilot board current sensor is faulty
causing the Relay board D11 to be on. Replace the Pilot board assembly.
b. If the Pilot current signal on the pilot ribbon cable was zero, measure between pins 23 (-) and 25 (+) on
the 40 pin ribbon cable between the Relay board and the CCM. This would also normally be zero if there
is no pilot current. Anything else would indicate the Relay board is faulty.
Art # 12307
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J23
TO RELAY BOARD
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J4
From I/O PCB
24VDC_SW
D21
GREEN
D23
RF ON
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5
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K2
RAS CONTROL
120
VA
C
120 VAC to RAS
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J8
120
VA
C
R
ET
120 VAC_1
From J9-1
120 VAC_RET
From J9-7
CCM I/O Board
Relay & Interface Board
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J59 - RAS
(98)
(99)
T2
120 / 6000 VAC
(98)
(99)
6.5K 1W
6.5K 1W
AC200XT only
(Rear Panel)
TP1
GND
TP1
GND
/ RAS ON
8. If “ /RAS ON” signal is low on pin 16 of the 40 pin ribbon cable, relative to TP1 on the CCM I/O board,
during the ignition time then we need to determine if the Relay board is defective. If /RAS ON signal is
not low the CCM or the 40 pin ribbon cable may be defective.
a. If the Relay board RF ON LED, D23, is not on while the /RAS ON signal is low, then the Relay board is
defective.
b. Is D23 is on, measure for 120 VAC on J8-3 to J8-11. If not present the Relay board is defective.
c. If 120 VAC is present at J8 during the ignition time go back and perform steps 2-4.
Troubleshooting Pilot Board problems.
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.