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STR 631 / STR 632
Port 8
Port A
Bit 0 is an active HIGH input CLEAR from the VideoCrypt circuit
indicating that a non-scrambled signal is being received.
2.1.Non Volatile Memory
3. Power Supply
4. Tuner
GRUNDIG Service
Schaltungsbeschreibung / Circuit Description
" The output of G drives the mixer which feeds the Surface Acoustic
- Wave Filter (SAWF). This band limits the nominally 479.5MHz second
IF signal to 27MHz. After filtering the signal is FM demodulated to
provide the baseband video output of the tuner on pin 9. A low pass
filtered version of the video signal is passed to a 5 level analogue to
digital converter inside the Programmable Counter so that it can be
read via ?C for AFC purposes on models which have Search Tuning.
Signal selection is achieved by use of a Phase Locked Loop (PLL). The
Local Oscillator (LO) is of the voltage controlled type. The output of the
LO is divided down by the programmable counter and its phase
compared in the Phase Detector with a crystal controlled reference.
The output voltage from the Phase Detector is used to control the LO
so that the value in the Programmable Counter precisely defines the
LO frequency which goes to the mixer.
es
22KHz
LNB_OFF
NB_SENSE
=
Control signals to and from IC600
Tuner Biock Diagram
5. Video Noise Filter
6. LNC Power
2-5
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