Download Vitalab Flexor E Service Manual

3. SYSTEM ORGANIZATION
3.6
SERVICE MANUAL
PHOTOMETER BOARD
On the Photometer Board is the photometer electrical circuit. In the figure below the
block diagram of this board shown.
Figure 3.8 - Block diagram Photometer Board
The complete electrical diagram is given in section 8 of this manual.
3.6.1 PHOTOMETER CIRCUIT
The photometer circuit can be divided into the following two circuits:
• programmable input amplifier
• lin/log converter
On the photometer board are two identical circuits present; one for the actual
measurement (PHOTOM), and one for the reference measurement (LAMP-REF).
The function of the reference measurement is to compensate variations of the lamp.
Because these circuits are identical only the operation of the actual input amplifier is
explained.
The principle of the input amplifier is illustrated in figure 3.9.
The figure shows the actual amplifier (IC11) with one of the photo-diodes as input
source and four switches controlled by the microprocessor (of the system board).
By means of these four switches, sixteen different possibilities for the gain settings
can be programmed.
3.12
VITAL SCIENTIFIC