Toshiba D-VR3SU Service Manual page 144

Circuit Operating Descriptions
7-12 TM
(1) Outline
RF and frequency synthesized tuning system
General description : The receiving circuit consists of both ANT input and output circuits, channel selection cir-
cuit, PIF circuit and SIF circuit. The receiving circuit selects a desired broadcast signal from TV signals induced on
an antenna and sends stable video and audio signals to their respective processing circuits.
(2) Tuner modulator block
As explained, this model is designed in one package to contain a RF MODULATOR BLOCK, TUNER BLOCK
AND IF DEMODULATOR BLOCK. Its size is greatly reduced and other noise interference can be minimized to
make performance high.
ANT INPUT
Off
through
SW
ANT OUT
TV SET
7-44
(MODULATOR SECTION)
Fig. 7-29 Tuner/demodulator Block Diagram
(TUNER SECTION)
VHF Mixer
RF AMP IC
UHF UHF VHF
RF AMP Mixer OSC
UHF
OSC PLL
IC
7 9 10
X-TAL SCL SDA
IN
(IF SECTION)
SAW IF Video
Filter AMP Detector
FM SIF
Detector Filter
AFT
AGC
13 11 16
AUDIO OUT VIDEO OUT
AFT OUT