Philips FW-C50/37, Service Manual

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(e.g. FB206,FB208).
AF6 Board (Source Select & Audio Control) Brief
Introduction
The AF6 Board consists of the following features :
a. SOFAC IC
SOFAC IC TEA6321 (7511) which includes functions such as source selection, loudness control, dynamic
bass control, treble control, front/rear volume control and muting function. Sound features such as DBB,
DSC and IS are controllable via I
2
C Bus from the microprocessor.
The SOFAC IC caters for 4 input sources, namely tuner, tape, CD and AUX.
It also has a MONO input which is tied to ground via a capacitor. In our application, software will switch the
input source to previous source MUTE during STANDBY mode and some other occasions where noise from
other input source is undesirable.
Note that the input to the SOFAC IC must be ac coupled to prevent ‘plop’ noise.
Input networks are included to provide appropriate attenuation for various sources.
b. KARAOKE MIC. MIXING
The AF6 Board has provisions which can be configured to cater for one of the following:
NK : Non-Karaoke.
SK : Simple Karaoke which caters for single mic. mixing with additional mic. amplifier board.
FK : Full Karaoke which caters for double mic. mixing with additional mic. amplifier board.
c. DOLBY PRO LOGIC (DPL) INTERFACE
The AF6 Board has provisions which can be configured to cater for Dolby Pro Logic (DPL).
d. LINE OUT
Line out with cinch socket for connection to external amplifier.
e. SUB-WOOFER OUT
Sub-woofer out with cinch socket for connection to active sub-woofer speaker.
f. INCREDIBLE SURROUND
Incredible surround effect using transistor circuit to create phase shifting and spatial effect.
g. HEADPHONE AMPLIFIER
Headphone Amplifier to drive 32 ohm to 1kohm headphone.
h. CD STANDBY CONTROL
CD Standby Control circuit which switches on the supply to CD servo control IC, HF circuit and the laser light
pen in CD mode only.
i. ATTENUATION NETWORK
Attenuation network is provided at the output of the AF6 Board for interfacing with power board of
different output power