Siemens TC12 Installation, Commissioning And Maintenance Handbook page 76

For UK use the output power is always set to -13dBm and the receive threshold is
set to –39dBm.
No other setting except for –13dBm is to be used in the UK for the output power
setting.
4. S4 - 2 / 4 Wire Select Switch
Set the 2/4 Wire Select Switch to the setting indicated on the installation sheet for
the Outstation (see Figure 21 for switch positions).
5. S6 - 600 Ω / High Impedance Switch
Installation is to be performed by a qualified / authorised installation / service
engineer.
THIS SWITCH IS LOCATED UNDER THE PCB COVER. FOR UK USAGE
THERE ARE NO USER ACCESSIBLE PARTS UNDER THE COVER. STC
WARRANTY WILL BE INVALIDATED IF THE COVER IS LEFT OFF OR
MISSING.
This switch is always set to the 600 Ω position for all Radial, Multi Point and/or
Multi Terminal lines. The switch is set to 600 Ω during manufacture and therefore
does not need to be changed. Where British Telecom or other telephone line
supplier has agreed to provide Multi-drop circuits i.e. where more than one OTU is
to be connected to one line, the final OTU on the line is set to 600 Ω, all others on
the line need to be set to high impedance. Then the switch may be set as
appropriate for the OTU, as noted below. This also applies to dual OTUs where
both OTUs are connected to the same line - only one of the OTUs may be set for
600 Ω if appropriate. The switch on the other OTU should be set to high
impedance.
Note to Service / Installation engineers:
This switch is located underneath the cover. The top half of the cover should be
removed in order to set the switch. No cabling should be connected at this stage,
but before removing the cover make sure that the cable connected to socket SK4
of the PCB is not connected to the telephone network. Ensure the cover is re-fitted
correctly after setting the switch. See Figure 21 for switch settings.
Make a note of the switch setting on the OTU installation sheet for future
reference.
6. The PCB can now be replaced back in the card guides.
666/HE/43100/000
TC12 Installation, Commissioning & Maintenance Handbook
WARNING
Page 66 Issue 10