Name
Date
Designation
Prepared
JF 05.07.13
Service Manual BB 150
Index
Name
Date
Document No.
Page
File
50078923_04_CN
50 079 823
6/ 6
Main board P003
(also main board or main PCB)
Provides the following functions:
Mains power connection:
Device power socket with integrated fuse holder
Power supply creation:
The combinational circuit component (input voltage range ~ 80 - 270 V) generates
the 12 V DC low power voltage for the electronic components. Voltage is
displayed by an LED.
Temperature and CO
2
calculation and regulation:
The measured values from the sensor board are adjusted by the offset and
amplification, and corresponding set values are generated. Control of all software
routines.
Actuator controls:
All heating system actuators are located on the main PCB. .
CO
2
solenoid activation:
The 12 VDC CO
2
solenoid is connected directly to the board. .
Sample protection:
In case of overtemperature, a special software routine linked to a universally
switching relay assumes the temperature regulating function. This upper
temperature limit band (set value +1
°
C) acts as the trigger band for this
controller. The software attempts to readjust the unit to the specified desired
temperature value. .
Fault detection and display (software):
The error diagnostics system detects faulty functions and passes corresponding
information to the display board.
RS 232 interface:
An RS 232 interface is part of the standard unit equipment.
Control of the zero-potential alarm contact:
In case of a fault, the standard alarm contact (center-zero relay) is activated.
Door switch connection:
The glass door state is determined by the door switch (contact closed when
the glass door is open!).
