TC12 Installation, Commissioning & Maintenance Handbook
666/HE/43100/000
Page 50
Issue 10
b) 2 wire system but with 4 wire selected in error:
No reply message will be received. Only the yellow LED for the modem will come
on.
(4)
SW5 - Transformer Select Switch
a) On board transformers required but off board set in error.
No Control signal on the line and therefore no received signal. The yellow LED will
be on and the green LED off.
b) Off board transformers required but on board set in error.
The power output of the control message on the line will be reduced.
2.4.4 Effect of Incorrect Switch Settings on the Transformer PCB
S1, S2, S3 and S4:
If the switch is set On when there is an OTU on the line then no Control message
will be sent to the OTU.
If the switch is left switched off when there is no OTU on that line, this may affect
the integrity of the control signal to other OTUs connected to the same modem.
2.4.5 Effect of Incorrect Switch Settings on the Digital Output PCBs
S1 - PCB Address
If PCB addresses are duplicated on one or more boards, the outputs on each
board will be set identically.
2.4.6 Fault Finding at the Instation
2.4.6.1 UTC TCC Communication Problems
Symptom Possible
Reason
No UTC TCC
communications with
Instation, SIP VAX LED on.
Incorrect installation of PC Ethernet card or cables or
faulty Ethernet card. On the 3Com Ethernet card,
failure to disable the memory can cause this failure.
No Ethernet cable/cable not attached.
A 50 Ohm termination has been missed off one of the
Ethernet T-pieces, either at the UTC TCC or at a PC.
PC address on PSU board is set to invalid number
i.e. 0 or F.
PC address on PSU PCB is set duplicated in another
Instation; only one Instation will operate correctly.
IMD Interrupt Vector switch DS2 incorrectly set.
No UTC TCC
communication with
Instation, SIP VAX LED off
PC not powered up - Check PC power LED on PSU
PCB.