Tweco Troubleshooting Power Supply - Manual (Page 17)

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INPUT_NG is derived from VACIN which comes from PCB1 where the 3
phase input is rectified and divided (See section on Voltage Selection & Wrong
Voltage Detection for full explanation of how VACIN is derived) and goes to
CN2-1 on PCB3 where it is passed directly to PCB4 which is daughter board that
plugs into PCB3.
PCB1
VACIN can be measured at CN2-1 (+) and PGND CN2-2 (-) on PCB3 (WK-
5694). PGND can be accessed easiest at CN1-1 on PCB3. It is also present at
CN2-2. Note, CN2 must be connected while taking this measurement.
It should be between 7.7 to 9.5V for 460 VAC or 3.5 to 4.7 V for 208-230 VAC
Power. For units with 400V input voltage (CE & CCC units) VACIN ranges
from 6.25 to 8.25V. 600V?
If 3 phase power of proper voltage is connected to the power supply and VACIN
is not within the values above, or is zero, PCB1 or connections to it may be
defective.
R1 on PCB4 is in parallel with R11 on PCB1. It is also possible (but less
likely) that if there was an open connection where PCB4 plugs into PCB3 or an
open trace on PCB3 or 4 so that R1 wasn’t connected then VACIN could be a
little higher expected. If the connection between CN2-2 on PCB1 to CN2 on
PCB3 is open VACIN may be a lot higher.
PCB4
If VACIN is correct and you know the inverters are configured correctly you
can quickly test PCB4 by removing CN7 from PCB4. If the contactors now close
PCB4 was defective.
The signal INPUT_NG going from CN7-4 on PCB4 to CN7-4 on PCB5 should
normally be false (low, near zero,) relative to TP0 on PCB5. You can also
measure from CN7-3 (+) to CN7-4 (-) on either PCB4 or PCB5. In this case if
INPUT_NG is false, the normal condition, you should measure +15V. If PCB4
is making INPUT_NG true then the opto isolator on PCB4 is on connecting +15V
on CN7-3 to CN7-4 making INPUT_NG high relative to TP0. Removing CN7
removes the high. If VACIN was in the correct range but INPUT_NG is true then
PCB4 is defective.
CCM
If code 2-2 occurred with Start applied, CCM will latch the code until Start is
removed and reapplied. To be sure the code is not latched, remove Start, shut off
power supply then turn it back on. PCB5 places signal Input Voltage OK (low)
on CN11-15 (34 ckt ribbon) which is J36-15 on CCM. If, after following steps
above, this signal is low and code 2-2 is flashing CCM may defective. It is also
possible, as explained earlier in this section, that the CCM and the rest of the
system are responding correctly to transient dropouts or surges.