Thermal Dynamics MERLIN 6000, Руководство по обслуживанию, Страница: 40 / 112

SERVICE TROUBLESHOOTING 34 Manual 0-2569
c. If none of the above is cause of READY LED
being OFF, then the Logic PCB is faulty.
2. RUN LED on Logic PC Board is OFF.
a. READY LED is OFF, refer to above.
b. PURGE FROM REMOTE signal input, J1-21 is
low (from Gas Control Module).
c. Set from remote input J1-17 is low (from Gas
Control Module).
d. If none of the above is cause of RUN LED be-
ing OFF, then the Logic PCB is Faulty.
3. START LED on Logic PC Board is OFF.
a. START signal (active low) not getting to J1-19.
Check wiring between Logic PCB and TB2 or
J15 remote connector. Check remote control
(refer to remote control section below). Check
CNC interface. Refer to Appendix XI and XII.
b. Logic PCB faulty.
4. START LED on Logic PC Board is ON momen-
tarily, less than 1/2 second, then OFF.
a. START signal applied only momentarily. Prob-
lem with remote (refer to remote control sec-
tion below) or CNC only giving momentary
START signal.
b. Faulty Q1. Refer to Section 4.05-M.
5. START LED is ON for pre-flow time then OFF,
but W LED never comes ON.
a. Plasma gas pressure or flow too low. Adjust
for higher pressure or flow.
Refer to Section 4.05-H, Gas Solenoid Circuits for details.
6. START LED stays ON and pre-flow gas contin-
ues to flow past normal pre-flow time.
a. Faulty Logic PCB, stays in pre-flow.
Main Contactor (W) indicator is ON momentarily, less
then 1/2 second, then OFF.
1. The W LED is ON momentarily. START LED is
ON for pre-flow time then W LED comes ON for
less than 1/2 second, then both W and START
LEDs are OFF.
a. No DC or DC less than -60 vdc. Front Panel
DC LED does not come ON. Install a jumper
from TP4 to TP1 on the Logic PC Board to by-
pass the DC sensing circuit. If the problem is
no DC then the W contactor should now stay
ON for 3 seconds then go OFF. No DC may be
caused by a faulty Q1 (refer to Section 4.05-
M). If contactor still drops out in less than 1/2
second, problem is not a loss of DC but may be
a shorted torch.
b. Shorted torch (head, leads, consumables, etc.).
Remove and insulate wire #7 from W7 faston
on Logic PCB.
CAUTION
300 volts may be present on the wire.
If contactor stays on for about 3 seconds after
remove wire #7, the problem is a shorted torch,
tip to electrode, with voltage on the tip exceed-
ing 220 volts.
Main Contactor (W) on for 3 seconds then OFF; No pi-
lot.
1. START LED is ON for pre-flow time, then W LED
comes ON for 3 seconds. Both W and START
LEDs go OFF.
a. Pilot must start in 3 seconds after DC comes
ON. Both pilot enable (U15-2) and tip voltage
(U27-14) signals must be high within 3 seconds.
If the spark gap (in Arc Starter Box) is firing
during the 3 seconds, check for wrong pilot
resistor setting (refer to 4.05 Section-S, Pilot
resistor Adjustment), bad torch parts, or open
connection in the torch leads.
b. If spark gap is not firing, check for 24 VAC (Arc
Starter Box PC Board LED is ON) and DC
greater than 250V at E1 & E2 fastons on Arc
Starter PC Board (DC will only be on for 3 sec-
onds - see note). If both voltages are present,
the Arc Starter PC Board is faulty.
NOTE
Logic PC Boards with Rev 'D' or later on the PC
Board have a test point, TP7, connected to the an-
odes of D67 and D72. When TP7 is jumpered to
TP1 it will defeat the pilot sensor allowing more
than 3 seconds for troubleshooting.
Pilot starts but Main Contactor (W) shuts off immedi-
ately upon arc transfer.
1. Contactor shuts OFF at arc transfer.
a. Current Control signal (DEMAND) greater than
10 vdc.
Measure for 10 vdc on the Switching Control
PC Board from TP1 (ground) to Front Panel
CURRENT Control, J10-15, or to the Remote
Current Control, J7-18 (see NOTE).