P/N 66109923001 Rev. A
9
TROUBLESHOOTING
Table 5 lists error symptoms and suggests troubleshooting actions.
Table 5: Troubleshooting
Power Faults
No LEDs illuminated
Check fuses
Check wiring
Verify DC voltage to unit
If power is present, ACU may be off-line
No communciations on one port
Check port fuse
Check port wiring
No power at one or more ports
Check fuses for affected ports
Check wiring for affected ports
Communications Errors
All lights steady except on one port Data A and data B wiring may be reversed. Check wiring on port with unlit LED.
Excessive data errors
Check wiring shield connections for ground loops
Check termination resistors and jumpers
C
OMMUNICATIONS
E
RRORS
1. Keep port with the ACU connected to the NexStar (see Figure 12).
2. If the ACU branch does not include other S-Net devices, connect a second branch (see
Figure 13).
3. Verify correct operation of ACU and S-Net devices.
4. If problems are detected, perform troubleshooting procedures for communications errors
as listed in Table 5.
5. When no problems are detected, connect other branches, one at a time, and repeat steps
3 and 4.
