Tweco Troubleshooting Power Supply - Manual (Page 23)

23
Inverter
The active low signal /READY TO OPERATE comes from PCB5 and is sent
to the CCM on J36-13 (34 ckt ribbon cable).
Signal INV_READY comes from the inverter(s) as an active high (open
collector) on CN6-8 (16 ckt. ribbon) to PCB5, WK-5602A. Any inverter can pull
the line low if it is not ready.
On PCB5 the active high signal is inverted to become active low signal /READY
TO OPERATE. /READY TO OPERATE is sent to the CCM on J36-13.
For the first few seconds after power is turned on, a timer, IC17, on the
inverter PCB13 keeps CN6-10 high. This in turn forces INV_READY low and
/READY TO OPERATE high.. This allows time for the input capacitors to charge
up through the inrush resistors. Then after a few seconds, IC17 times out holding
CN6-10 low.
If the capacitors have not reached proper voltage at the end of the inrush time
will set code 2-4. It will also light an LED3, DCV_ERR on PCB13 of the
defective inverter. This can happen if the inrush resistors (R1 & 2 on the inverter
module ) are open of disconnected (CN4 on PCB 9).
If the contactor is on, supplying power to the inverter, measure the
INV_READY signal at CN6-8 (TP0 on PCB5 common) normally +15VDC. Also
measure J6-10 which should be low. If either are wrong, inverter is defective.
If there are two or three inverters you can disconnect ribbon cable from CN6 of
one inverter at a time (other ones remain connected). When 2-4 code goes away
that was the bad inverter.
PCB5 & CCM
If CN6-8 is high, +15VDC, and CN6-10 is low then measure J36-13 on CCM
(CCM TP1 common). If J36-13 is low then CCM is defective. If it’s high PCB5
is bad.
Code 2-4 combined with 3-4 & 4-2 when the Plasma Enable on the GCM 2000
or 2010 gas control is set to disable can indicate a fault in the CCM I/O PCB.
When switching back to Enabled the pump will not restart so continues to display
4-2 indicating no coolant flowing.
Normally the code during a disable should be 1-1. Circuits on the I/O PCB
detect the Plasma Enable is disabled and send signal to the microcontroller in the
CCM. If that signal doesn’t get passed the microcontroller doesn’t know system is
disabled so sets these 3 codes.
2-5 DC Output Low
Immediately after receiving Start signal from CNC, inverters are enabled and
CCM measures the power supply output voltage between negative (Torch) to
positive (Work) at the output busbars. If this is less than a set value during
preflow or if at any time during piloting or cutting it drops to below that value for
a short time, code 2-5 is set. Currently that value is -60V.