Table of Contents
Advertisement
Circuit Descriptions, Abbreviation List and Data Sheets
As capacitor C2869 is not charged at power start-up, transistor
TS7773 will block and pin 6 of audio switch IC7753 is 'high'.
This means that the sound is muted. After charge-up, TS7773
will conduct and the audio signals are passed.
9.3.3
RGB Path (Diagram F)
RGB signal path
To Auto Scavem
+12V
3421
3426
7416
4001
5001
3423
'B'
3424
Figure 9-2
The RGB signals from the HOP are fed to three identical
amplifiers (TDA6120). We take one of them (B, item 7330) as
example for the description. After emitter follower TS7416, the
signal is tapped for the Auto Scavem circuitry, and is fed to
TS7417. This emitter follower sends the signal, with the same
DC-voltage, to the amplifier. In order to cope with the higher
definition, this IC has a larger bandwidth (20 MHz) as the one
used in the MG3.1E.
9.4
Feature Box 7 (Diagram L)
The objective for this chassis is was, to reach a sharper picture
by means of a higher definition.
This is achieved via the so-called 'Pixel Plus' feature. So, what
is Pixel Plus?
9.4.1
Introduction
In the Feature Box 7 (FBX7), a new IC is used, called the
'Eagle'. This IC does the following picture improvements:
•
Horizontal: increases from 840 to 1680 pixels per line (the
number of pixels is doubled per line). This, by itself, does
not mean an improvement in definition however. To
achieve that, the new pixels are digitally processed inside
the Eagle with Luminance Transient Improvement (LTI)
and Peaking. This will give the new pixels extra picture
information, which results in steeper slopes and contrast
improvement at details.
•
Vertical: increases from 625 lines (PAL) to 833 lines. Also,
those new lines are processed inside the Eagle with LTI
and Peaking, again resulting in lines with extra picture
information.
•
The line frequency is fixed on 31250 Hz and the frame
frequency at 75 Hz (this will give no frame-flicker). Also,
other modes, like 'Digital Scan' are still possible.
•
The colour enhancement features of the TOPIC are done
by the Eagle.
3425
7417
3427
3336
4336
To TDA6120
(pin 2)
3332
5336
2331
CL 16532149_080.eps
9.4.2
Block diagram
FBX7
INGANG
FILTERS
HA
VA
131201
The 50 Hz YUV signals, coming from the HIP, are fed to the
PICNIC via an anti-aliasing filter.
The (AABB) frame frequency doubling is done by the PICNIC
(SAA4978, 160 pins QFP) together with a field memory
(MEM1). This IC can handle most 100 Hz functions (except
Progressive Scan).
This PICNIC has an internal CPU and a (small) integrated
ROM. The actual FBX7 software is located in an external ROM
(item 7711). In order to limit the number of connections
between the PICNIC and the external ROM, a number of lines
are used twice. The lines A8 to A15 are fixed lines, while the
lines A0 to A7 are made switchable with the eight data lines of
the ROM. This is done via a Latch (item 7712), which is
controlled by pin 139 of the PICNIC (the ALE signal).
Via bus 'C', a digitalised signal is presented to MEM1, which is
used for the 50 to 100 Hz conversion. The signal goes further
via the data-bus to the FALCONIC. This IC has the following
functions:
•
Line flicker reduction.
•
Digital Noise Reduction (DNR).
•
Progressive scan (262.5 - 525 or 312.5 - 625 lines per
frame).
At the end, the digital YUV signals enter, via MEM4 and MEM5,
the Eagle IC.
This IC has the following functions:
•
Luminance Transient Improvement (LTI).
•
Peaking.
•
Programmable number of lines.
•
Programmable number of pixels per line.
•
Demo mode (split screen).
•
Improved colour transients (CTI) and colour enhancement
(TOPIC).
•
Improved vertical zoom.
The digital YUV-signals from the Eagle go, via a passive output
filter, to the HOP.
As only the Eagle IC is new, it is described below in more detail.
For a detailed description of the other ICs, please check the
training manual of the MG3.1E.
9.4.3
Eagle (Diagram L2)
Introduction
Some strong picture improvements are carried out inside the
Eagle, which all contribute to the excellent picture quality.
These improvements are:
•
LTI (both horizontal and vertical).
•
CTI (only horizontal).
MG3.2E
IC 7718
IC 7714
SAA4992
MS81V04160
MEM1
8UV
FALCONIC
8Y
8UV
8UV
8UV
8Y
8Y
8Y
IC 7722
IC 7723
MEM 5
MEM 4
8UV
8Y
8UV
8UV
8Y
8Y
IC 7724
EAGLE
HD
WE IE
RE D
BUS C
BUS D
IC 7713
SAA4978H
ADC
PICNIC
AKTIEF
HOOG
.139
A0...A7
ALE
IC 7712
LATCH
AKTIEF
IC
HOOG
EN
A0...A7
D0...D7
A8...A15
IC 7711
M27C512
64k PROM
Figure 9-3
9.
EN 147
WERK
IC 7717
GEHEUGEN
MEM 2
100Hz
IC 7719
DIG
MEM 3
SCAN
VD
YUV_EAGLE
UITGANG
DAC
FILTERS
HD
VD
CL 16532149_081.eps
061201
Advertisement
Table of Contents
