Service manual

Section - VI Reading Station BT3000 PLUS Rev. 0, Soft Ver. 8 Page 10 of 12
6-8. INTERFACE BOARD (15-04270-01)
The ISE sampling arm heater, the cuvette motor, Peltier modules of the reading
station system and their cooling fans, the Hall sensor, and the temperature sensor
are all connected to the Interface Board (Figure 6-2). A bi-color LED indicator is
also located on this board to visualize the hot/cold status.
NOTE:
The Master Logic Board, Master Power Board, Photometer, Halogen Photometric Lamp, Diluter
Pump, Peristaltic Pump or any other device on the reading station can be simply accessed through
an appropriate cover on the rear panel. This access cover has been designed into the system for
facilitating the inspection and maintenance operations. After receiving the information from the
central processing unit (IBM), the integrated electronics make the module an independent
intelligent peripheral.
6-9. THE 10-CHANNEL PHOTOMETER
The Biotecnica 10-channel photometer (Figure 6-1 and Figure 6-7) is a discrete
device and has ten channels with interference filters. Each channel has an
independent filter, photodiode, and amplifier. The unique optical system provides
for simultaneous illumination of all of the channels. The electronics circuit is
capable of communicating and acquiring signals from 2 channels for bi-chromatic
reading.
The 10 amplifiers and as many diodes are visible on the schematic (Figure 6-7).
Each amplifier is equipped with a trimmer for gain regulation. The gain adjustment
is necessary for adapting the signal level to the manufacturing tolerances of
optical components. The two multiplexers, U6 and U7, and their outputs that are
connected to the inputs of two A/D converters, U8 and U9, establish the
simultaneous selection of two channels. The conversion is serial type. The digital
impulses pass through the U10 Gate (74LS132) with Smith trigger function. The
two multiplexers are addressed by the µC764 (master logic board) with 4-bit per
multiplexer. The electronic circuit of the photometer is powered by ±12 Volts for
the analog circuits and +5 Volts for the digital circuits. A 16-conductor flat cable is
used for connecting the photometer to the master logic board.