Skanti TRP 9250, Technical Manual, Page: 143 / 289

The interface part includes Rx/Tx relay shift, balanced AF line driver for the ScanBus connection
to the control unit, and digital interface for auxiliary input/output.
Connection Board 936:
The connection board contains the DC supply input terminals and terminal strips for connection of
other units. Fuses and diodes for protection against supply voltage reversal and over-voltage are
also located on this board.
AC Power Supply Board 958 (optional):
The AC power supply board contains an input filter followed by a rectifier (230V)/voltage doubler
(115V) circuit producing an unregulated DC voltage which is converted to 28 V in a full bridge
Hy-bridge converter with soft switching and integrated magnetics. The output voltage is adjusted
by a regulator circuit optically isolated from the driver circuit. Power for the driver circuit is supplied
from a separate winding on the main transformer. A temperature controlled fan contribute to cooling
if necessary.
The output is connected to the DC supply input terminals of Connection Board 935. A 24 V battery
connected to the battery terminals will by means of a relay be connected to the output in case of
mains failure.
An over-voltage/over-temperature protection circuit disables the SMPS by triggering a failure lock
circuit in case of excessive output voltage or temperature. If the failure lock has been triggered it is
necessary to disconnect the mains for min. 7 minutes to allow the primary capacitors to discharge
before the SMPS can be switched on again.
Charger Control Board 959 (optional):
The charger control board enables the AC power supply to be used as a battery charger. With the
switch set to position ’Auto’ the battery relay in the AC power supply connects the output to the
battery terminals, provided a battery is connected and the voltage of the battery exceeds approx.
17 V.
The power supply operates as a constant current/constant voltage charger. The output current
capability is min. 24 A. The float voltage is adjustable by means of a potentiometer on the charger
control board. Constant current mode is indicated by a yellow ’Main charge’ LED while constant
voltage is indicated by a green ’Float charge’ LED. The board also contains alarm circuits for low
and high battery voltage and terminals for AC alarm output. Temperature sensor inputs are provided
for compensating the float voltage and the high voltage alarm setting.
Interface-A 718 (optional):
PCB 718 consists of data drivers and receivers, AF line drivers and receivers, and general purpose
input/output circuits. The optically isolated data drivers/receivers are for control of the transceiver
from an external modem. Galvanically isolated balanced 600 ohms input and output lines are
available for transfer of the AF signals with a +/- 10 dB adjustment possibility of the AF output.
TECHNICAL DESCRIPTION TRANSCEIVER UNIT TU 9250
4-6 TRP 9250 TECHNICAL MANUAL