Loewe Q2500B Serviceanleitung Seite 202

Technology of Q 2500 colour TV set
The picture signal processing is mainly in digi-
tal form, with ICs from different manufacturers
being used. The video processor VPC 3230
developed by Intermetall is used in the front
end. A Philips IC set is used for the 100 Hz
processing. This IC set was reduced by higher
integration to two chips and the two half pic-
ture memories. The new SAA 4993 in the
Q 2500 chassis is used for the latter. The mi-
crocontroller, the memory controller, the
50/100Hz memory and the DAC are all com-
bined in the SAA 4979 (BESIC). In the back
end of the Q 2500 chassis there is a new pro-
cessor that contains both the video and the
deflection function. The Philips TDA 9332
video/deflection processor has the item num-
ber I 2521.
In addition, the Q 2500 chassis can also be
optionally equipped with picture in picture
processing. This enables one or three small
pictures to be inserted (see picture in picture).
A split screen is also possible for the first time.
4.2.13 Components for signal processing
The following is a short overview of the com-
ponents and their functions as used for signal
processing. The signal path, pin-assignments
and the exact functioning is explained later.
The processing is also described in detail
later.
- VPC 3230
Video processor
8-bit ADC for FBAS and Y/C signals
4-line comb filter
Multi standard colour decoder for PAL/
NTSC and SECAM
20.25 MHz clock generator
Letterbox detector
Line compression and decompression
for zoom modes
- 2 x MSM SAA 4955 HL
Half picture memory
The two half picture memories are neces-
sary for the picture
signal intermediate storage and
processing.
- Philips SAA 4993
Document Q 2500
(Falconic: Field and line rate converter
with noise reduction IC)
Dynamic noise suppression set by user.
Suppression of intermediate line flickering
DLC (Digital Lineflicker Reduction).
Suppression of motion in horizontal move-
ment, DMI (Digital Motion Interpolation).
Suppression of motion in movies, DMM
(Digital Movie Mode).
Line interpolation, in order to display 576
lines in all zoom functions, DLI (Digital Line
Interpolation).
SAA 4979
-
(BESIC: Back End System control IC)
The integrated half picture memory is for
50/100Hz conversion.
Control of 100 Hz signal processing
Synchronisation of 32 MHz
Peaking and CTI (Colour Transient
Improvement) to improve Y and
chroma interfaces.
Horizontal sampling
DAC for Y, R-Y and B-Y
- TDA 9332
(Video/deflection processor)
Inputs for two separate RGB signals.
PAL/SECAM and NTSC matrix for produc-
tion of RGB signals.
Colour saturation, brightness and contrast
settings.
Automatic Cut Off and leakage current con-
trol and setting.
Beam current limitation circuit.
RGB output amplifier.
Production
signals
79
of V/H deflection
© Loewe ProCollege
control