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Chapter
2
1.
Control and Teletext Processing
1.1.
Control Processing
The following section only highlights changes in
control processing which have occurred with the
introduction of new models into the EURO 4 line up,
and should be used in-conjunction with the EURO 4
technical guide.
The Microprocessor IC1101 used on the EURO 4
chassis is the SDA5450 which performs the same
processing
tasks
as
microprocessor used on the first generation EURO 4.
This includes not only control processing but teletext
processing too.
Listed below is those changes:
1.1.1. Input Control
:
Pin 54 - Reset In
This input terminal is used as a power OFF reset by
the microprocessor IC1101 when the TV is switched
into standby. Without this power OFF reset the
microprocessor IC1101 has no way of knowing the
operational condition of the TV.
When the TV is switched OFF the operational data
from the digital processing ICs is lost. This means that
at switch ON this data has to be reloaded.
To be able to do this the microprocessor IC1101, has
to be reset so that at switch ON from standby the
operational data is reload into the digital processing
ICs. This is achieved with reset IC IC1105, which
monitors the 5V supply line via pin 2. When the 5V
under
taken
by
supply falls to approximately 4.8V the reset IC IC1105
inputs a reset pulse via pin 54 of the microprocessor
IC1101.
:
Pin 71 - VProt
This input is used to detect a fault in the deflection
circuit. This is achieved by using the vertical
synchronisation
microprocessor IC1101 pin 47, via transistor Q1108.
This signal is also fed via diode D453 where capacitor
C455 is charged. The charge held by capacitor C455
the
results in a HIGH level being applied to the base of
transistor Q451, which ensures that the transistor is
switched OFF.
When transistor Q451 is switched OFF a HIGH level
is applied to pin 71 of the microprocessor IC1101, fed
via resistor R457. This HIGH level ensures that the
safety input of the microprocessor IC1101 is
in-operative.
Where an error occurs resulting in there being no
vertical synchronisation signal being fedback to
transistor Q451, capacitor C455 discharges via R458
resulting in transistor Q451 conducting. This results
in pin 71 of the microprocessor IC1101 being pulled
LOW and the TV switching into standby after a short
delay.
:
Pin 74 - RC
The users commands for control of the TV receiver
are applied via the remote control.
These commands from the remote control transmitter
are applied via the remote control receiver to pin 74
of IC1101, this command data being in serial format.
11
3DQDVRQLF
EURO 4 Supplement
signal
which
is
fed
to
the
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