Effect Of Incorrect Switch Settings On The Otu Pcb; Fault Finding At The Outstation - Siemens TC12 Installation, Commissioning And Maintenance Handbook

3.4.2 Effect of Incorrect Switch Settings on the OTU PCB

(1) S2 - Lithium Battery On/Off Switch
If this switch is off the system fail LED will illuminate on the OTU PCB the OTU will
not communicate with the Instation.
(2) S3 - Line level switch
A 6-way DIL switch is used to set line levels. If switch positions 1 to 4 of the DIL
switch are set incorrectly the OTU will transmit at the wrong output power.
WARNING - FOR UK USAGE THE OUTPUT POWER MUST NOT BE SET TO
If switch positions 5 and 6 are set incorrectly the receive threshold for the OTU
modem will be wrong. If it is set too low corrupted control messages may occur. If
set too high the control messages from the Instation may be undetected.
(3) SW4 - 2/4 Wire Select Switch
Four wire system but with two wire selected in error or two wire system but with
four wire selected in error: the OTU will not receive the control signal and will not
reply, therefore the carrier detect and transmit confirm LEDs will be OFF.
(4) S6 - 600 Ohm/High Impedance Switch
If the switch is set to high impedance when it should be set to 600 Ohms, the
transmit signal for all OTUs on the line and the receive signal for the particular
OTU will be up to 3dB higher than if the switch was set correctly. The
characteristics of the line may also be affected.
If the switch is set to 600 Ohms when it should be set to high impedance this will
reduce signal levels and may upset the characteristics of the line.

3.4.3 Fault Finding at the Outstation

Symptom
System Fault LED On
Watchdog LED On
OTU not replying to control message
OTU Inputs not working
666/HE/43100/000
TC12 Installation, Commissioning & Maintenance Handbook
GREATER THAN –13 dBm.
Page 134
Possible Reason
Use handset to access fault log for
information on the type of fault that has
occurred.
Software not running correctly. Switch off
and on again.
OTU Switch settings incorrect
OTU configured incorrectly via the handset -
repeat configuration.
NO power - Power led off, cable
disconnected/fuse blown.
No control data - low line level, interference,
BT lead disconnected or faulty.
Check fuse protecting 24 V rail
Issue 10