User's Manual

Table Of Contents
11 Troubleshooting (Fault Finding)
242
11.1.5 Irregular Ethernet Activity
The yello
w Ethernet LED should blink randomly as normal traffic passes through. If the
Ethernet LED flashes irregularly, for example there is a short flash followed by a long flash,
this indicates that the ODU has booted in recovery mode. The causes may be installation
wiring or a corrupt ODU software load. For more information, see Section 9 “Recovery Mode”.
11.1.6
Connection is not 1000 BaseT
If the Ethern
et connection to the network is only 10/100 BaseT, when 1000 BaseT is
expected, perform the following tests on the RJ45 cable that connects the PIDU to the LPU or
ODU:
1. Check that the wiring to pins 4&5 and 7&8 is correct. For example, the wiring to pins
4 and 7 may be crossed.
2. If this test fails, replace or repair the RJ45 cable.
11.1.7 Test RJ45 Resistance
If the above
procedures fail to diagnose the issue, there may be a fault in the wiring of the
RJ45 cable that connects the ODU (or LPU) to the PIDU. Unplug this cable from the PIDU,
then perform the following test procedure:
1. Check the cable resistance between pins 1&2, 3&6, 4&5 and 7&8 at the RJ45. Check
against column 2 in Table 39. Resistances for each pair should be within 1 ohm of each
other.
2.
Check the cable resistance between pins 1&3 and 4&7 at the RJ45. Check against
columns 3 and 4 respectively in Table 39.
3.
Ensure that there is greater than 100K ohms between pin 1 and ODU ground for all cable
lengths.
4. Ensure that there is greater than 100K ohms between pin 8 and ODU ground for all cable
lengths.
5. If GPS is not fitted, ensure that there is greater than 100K ohms between pin 1 and pin 8
for all cable lengths. If GPS is fitted, ensure there is greater than 2K ohms between pin 1
and pin 8.