3DQDVRQLF
21
Chapter
3
EURO 4H Supplement
1.1.2. Output Control
:
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. In standby mode pin 81 is set
to HIGH level which causes Q1052 (
Q1062 M-Board)
to switch ON causing 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.
1.1.3. I
2
C Bus
:
Pin48,49-SCL1,SDA1 / Pin 50, 51-SCL2, SDA2
The I
2
C bus is generated by the microprocessor, with
data line SDA1 being output via pin 49 and SDA2
output via pin 51, while the required clock lines SCL1
and SCL2 are output from pins 48 and 50
consecutively. While the operation of the I
2
C bus has
not changed, the ICs controlled by the I
2
C bus have,
these being:
The following are connected to I
2
C- bus 1:
On the F-Board the VPC IC1501, CIP IC1502,
SDA9401 IC1503, DDP IC1504 are responsble for
the video and deflection processing for 100Hz
models.
The multi standard sound processor (MSP) IC2101.
The tuner and I.F. stage
The 21 pin AV1 socket pins 10 and 12 are fed the
I
2
C-bus1 control line via the transistors Q3006 and
Q3007. During service mode, therefore, the T.V. may
be programmed with the aid of a remote control.
For those models with Dolby Pro Logic, the Dolby Pro
Logic processing IC DPL3520 IC2401 is controlled
directly by the microprocessor via I
2
C-bus1.
The following are connected to I
2
C- bus 2 :
The EAROM IC1102 is the only IC connected to I
2
C-
bus 2, which contains system data, programme
locations and specific tuning values, normal levels
etc.
1.2.
Teletext Processing
General
Teletext processing as discussed in the EURO 4
Technical Guide has not changed, however on the
EURO 4H with the deletion of the VDP and the
addition of the F-Board the output path has changed.
This sees the RGB signal being output from the
microprocessor IC1101 via pins 37 (R), 38 (G) and 39
(B) accompanied by a blanking pulse output via pin
40.
These signals are then fed to the VPC IC1501
(located on the F-Board) via connectors E70 to F1,
where the RGB signals are processed as discussed
in chapter 3 section 2.2.
Summary of Contents for EURO 4 Chassis
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