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12-1
AF8 BOARD
TABLE OF CONTENTS
Brief Introduction of the AF8 Board ............................... 12-1
AF8 Board - Component layout ..................................... 12-2
AF8 Board - Chip layout ................................................ 12-3
AF8 Board - Circuit Diagram (Part 1) ............................ 12-4
AF8 Board - Circuit Diagram (Part 2) ............................ 12-5
Electrical parts list .......................................................... 12-6
BRIEF INTRODUCTION OF THE AF8 BOARD
The AF8 Board consists of the following features :
a. TDA7437 IC
TDA7437 (7511) audio processor IC includes functions such as source selection, loudness, dynamic bass control, treble
control, front/rear volume control and muting function. Sound features such as DBB, DSC and IS are controllable via I
bus. All input sources are used namely CD, TUNER, TAPE, AUX and Differential input. Mono input is unused and terminated
to ground via a capacitor.
b. MIC. MIXING
The AF8 Board can provide simple karaoke (without echo) which caters for mic. mixing with additional mic. amplifier board.
c.
LINE OUT
Line out cinch is included for connection to external devices such as amplifier, recorders etc.
d. SUB-WOOFER OUT
Sub-woofer out cinch is included for connection to active sub-woofer speaker.
e. INCREDIBLE SURROUND
Incredible surround effect using transistor circuit to create phase shifting and spatial effect.
f.
HEADPHONE AMPLIFIER
A headphone can be driven by Op-amp NJM4556AM.
g. CD STANDBY CONTROL
Control circuit that switches on the supply to CD servo control IC, HF circuit and the laser light pen in CD mode only.
h. HEADPHONE SENSING
Headphone sense circuit is for switching off DPL modes when headphone is plugged in.
i.
ATTENUATION NETWORK
This is provided at the output of the AF8 Board for interfacing with power modules.
j.
BASS AUTOMATIC LEVEL CONTROL (ALC)
This circuit will defeat the bass effect if it sense that there is excessive amount of bass frequencies present in the left and
right audio channel. This will prevent the excessive speaker excursions under high volume condition.
k.
SURROUND OUT
Surround out cinch is included for Dolby Pro Logic versions when AF8 Board is used together with DPL PCB.
12-1
2
C
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