Thermo Scientific SAM12, Manual

Page: 25 / 176

Issue: 1.0 Description
Thermo Fisher Scientific SAM12 User Manual 2-3
protocol as well as providing an I2C bus for driving the LED
display(s).
DC-DC Converter Board Type 5675A
A proprietary DC-DC Converter pair produces reg5V
and
±
12V outputs directly from the Battery Controller Board,
type 5660A. Power is then distributed to the Controller Board
5670A.
Battery Controller Board Type 5660A
The Battery Controller Board, type 5660A, manages the
charging of a 12 volt sealed lead-acid battery. The whole
electronics system is powered from the 5660A Board. The
5660A constantly senses the charge/discharge state of the
battery and controls the charging voltage accordingly. The
charging voltage is temperature compensated by means of a
thermistor located on the battery. This helps to maximise the
life time of the battery.
A momentary key-switch, located on the side panel, allows
power to be switched to the electronics provided the battery
voltage is above a safe value (i.e. not discharged), even when
mains power is absent. The key-switch needs to be held ON
for at least two seconds before the ON state is engaged.
The 5660A continues to monitor the terminal voltage of the
battery during battery operation but will signal a shut-down if
the battery discharges to a predetermined point, beyond which,
it would suffer permanent damage and be difficult to recharge.
A miniature fuse protects against over-current conditions.
The application software would normally regulate shut-down.
In the event of the software losing control an emergency shut-
down is possible by holding the key-switch ON for a minimum
of 10 seconds (nominal).
FHT681 Scintillation HV and Amplifier Type
42543-0223
The Scintillation HV and Amplifier Board, type 42543-0223, is
a dual channel high voltage generator/scintillation amplifier
pair. The HV generators are sub-assemblies (type 42543-0202)
which are controlled by DACs (Digital to Analogue Converter)
on the main printed circuit board. The HV has a range between
0 and 1400 Volts, with a resolution of about 1 Volt.
The charge pulses arriving along the high voltage cable from
the detectors are amplified and each fed to five discriminators