3DQDVRQLF
12
Chapter
2
EURO 4 Supplement
1.1.2. Output Control
:
Pin 45 - 4:3 RGB
The 4:3 RGB control output from the microprocessor
is used to support the display of an RGB picture on
wide screen TV’s. This is achieved by mechanical
means as opposed software by transistor Q580 and
relay RL580. The 4:3 RGB control line being used to
control transistor Q580 responsible for controlling the
horizontal aspect ratio. Where the aspect ratio of the
picture is reduced to a 4:3 display the operating
voltage to the DAF circuit located on the W-Board has
to be reduced too, ensuring that the DAF correction
signal is also reduced to match the active picture scan
ensuring optimum picture conditions as described in
chapter 2 section 2.
:
Pin 53 - Reset Out
To ensure correct operation of the digital ICs, they
must be started at a specific time in order to permit
signal processing. This is achieved by the reset
control line output from pin 53 of the microprocessor
IC1101. During switch ON the digital ICs are held
LOW by Q1101 which is conducting at this point due
to the 5V standby supply fed to the base of Q1101 via
R1112. Once the supply voltages have become
established pin 53 of the microprocessor IC1101 pulls
the base of Q1101 LOW resulting in it switching OFF.
A HIGH level is then fed via R1111 to the digital ICs
initiating their start-up.
:
Pin 79 - Chroma Switch (M-Board
Only)
The chroma switch control output from pin 79 of the
microprocessor IC1101 is used to control the
switching transistors Q3202, Q3204 located on the
M-Board. This control line being used to select
between the chroma signals input from the S-VHS
inputs of AV3 and AV2.
:
Pin 81 - LED
The standby LED is controlled via pin 81 of the
microprocessor IC1101, which when In standby
mode causes the standby LED to light up. Pin 81 is
also used to flash the standby LED when the Infra-red
remote control receiver receives a signal from the
remote control.
Summary of Contents for EURO 4 Chassis
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