Panasonic EURO 4 Chassis Technical Manual page 142

Chapter 4
: Pin 58 - Slow1 / Pin 59 Slow2
The circuit is designed so that it is possible to switch
over to either AV1 or AV2 channels from all
programme locations, allowing automatic processing
of a composite video signal input from an external
source via the 21 pin scart terminals, by using the
Slow switch control line of AV1 and AV2.
Internal TV switching is performed by the video
switching IC IC3401 (located on the H-Board) and is
controlled by the microprocessor via I
placing an AV turn on voltage at pin 8 of the 21 pin
scart sockets, the relevant AV input will be
automatically selected.
These turn on voltages fed from AV1 and AV2 pin 8 are
fed from the H-Board to the E-Board. This sees the
slow switch signal from AV1 being fed via connectors
H11 and E28 pin 18. Likewise for AV2 the slow switch
signal is also fed from the H-Board to the E-Board via
connectors H12 and E29 pins 10. Once both the slow
switching signals are input onto the E-Board, they are
then fed to IC1101 and pins 58 (AV1) and 59 (AV2) of
the microprocessor.
Pin 8 of AV1 and AV2 scart sockets are also used to
allow the microprocessor IC1101 to perform
automatic picture ratio selection between 4:3 and
16:9 formats during AV operation.
However, a pre-requirement for this would be for
example, the provision of a video recorder able to
process both picture formats. It has been established
that during play-back recorders with a picture format
of 4:3, supply a slow switch control voltage of 12V, and
those with an aspect ratio of 16:9 supply a slow switch
control voltage of 6V. These switching voltages which
are fed to the microprocessor pins 58 (AV1) and 59
(AV2) as mentioned previously are fed via the
potential divider resistors R1131, R1128, and final
R1127 to pin 59 for AV2 selection. AV1 selection is fed
via resistors R1130, R1129 and R1126 to pin 58 of the
microprocessor IC1101.
The table shown below shows the required voltages
for aspect ratio selection.
  
  
  
2
C Bus 4. By
:
The local control commands fed from the local keys
are fed to the microprocessor IC1101 as serial data,
this data being input via pin 60. When no commands
are fed from the local keys pin 60 is held at 5V by
pull-up resistor R1256 (located on the H-Board) which
is connected to the 5V standby supply. This means
that this High level is also maintained during standby
condition. Operating commands fed from the local
keys results in varying voltages being applied to pin
60 which inturn initiates the varies controls.
Operating commands issued from the local and
remote control are treated with equal status,
:
During search mode the microprocessor IC1101
detects the AFC voltage input via pin 61, which is fed
from the tuner/I.F. stage.
When the AFC voltage reaches mid level between the
highest and lowest points of its swing, the
microprocessor stops the search operation and holds
the data.
:
FLT3 pin 63 is used for the phase shifting of the VPS
or teletext data.
FLT2 pin 64 PLL filter for VPS slicing.
FLT1 pin 65 PLL filter is used by the teletext slicer.
59
EURO 4D Supplement
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Pin 60 - Keyscan
Pin 61 - AFC
Pin 63 - 65 - FLT1-3
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