BBK AV310T Service Manual HANDBOOK

Principle and Maintenance Brochure for AV310T (RU)

Table of Contents

Chapter One: Product Introduction
Chapter Two: Working Principle

I. Components of the Complete-machine
II. Signal Processing Board
III. Decoder Board
IV. Panel
V. Power Board

VI. Loudspeaker Board & Protection circuit
Chapter Three: Appendix
Appendix I. Connection Diagram and Principle Diagram
Appendix II. Introduction to Major IC Pin Function

Chapter One: Product Introduction
AV310T (RU), the recently launched power amplifier of superior quality, has successfully
employed the DTS/AC-3 digital decoding functions to ensure high-quality sound effects, which
eliminates the sound distortion and noise in audio signal processing. AV310T (RU) is
characterized by:

1. Precise Operating Panel Interface: The complete-machine assembles a single power switch
button, menu button and a big knob in the operating board, which are easy to operate.

2. DTS/AC-3 Decoding Function

3. with Fiber, Coaxial Signal Decoding Function

4. Built-in 5-Channel amplifier was adopted to accord with AC-3/DTS and stereo music playback.
Strong in power, the main channel is 100w and the center& surround channel is 22w.

5. Equipped with 6-channel volume control and independent power control, and 7-segment
electric equilibrium

6. Equipped with multi-electric equilibrium mode to serve music of different styles.

7. Digital sound field time-lagging function

8. with built-in radio function

9. Qualified with over-power and over-pressure intelligent protection function

10. Karaoke function and earphone output

Chapter Two Working Principle

I. Components of the Complete-machine
AV310T (RU) consists of the following seven components:

1. Signal processing board: for signal gating, pre-amplifying and the pre-processing of Karaoke
signals

2. Decoding board: in charge of the control to the whole power amplifier and the digital signal
process;

3. Control Board: VFD Display, the menu button and main volume control

4. Power board and protection circuit: to supply the working voltage needed to unit circuit and
carry out the protection function to the whole power amplifier;

5. Amplifier board: to amplify the power of the 5.1-channel signal and simulated signal;

6. Earphone board: to amplify the karaoke input and earphone output signal.

II. Signal Processing Board

1. The six input styles of AV310T (RU): Fiber input, coaxial input, CD, DVD, 5.1-channel and
radio input.
The digital signal of fiber and coaxial input is processed in decoding board through lines. The
simulate input option of AV310T (RU)is realized through the two electric switches, the truth table
is as follows:

CD4052 Truth Table

CD Radio DVD
A 1 0 1
B 1 1 0

The three simulated input status : AV310T（RU）has the three simulated input states: radio, CD,
DVD, which are controlled through signal 4052-A and 4052-B respectively(refer to the truth table).
The gated signal is output from Pin 3 and Pin 13 of N101; then through N111 CD 4052, the main
channel signals of the right and left are output through Pin1 and Pin12; the signal is finally
processed in the decoding board.
The simulated signal input in 5.1 state: The 5.1 simulated signal input of AV310T（RU）controls is
gated by the two IC CD 4053s, Pin 9, Pin 10 and Pin 11 of which is controlled by the signal 5.1CH
output from Pin 4 of M62446. When signal5.1CH becomes high level, the strobe becomes the
State5.1 simulated signal input, under which the digital sound field disappears and all the signals
becomes direct. When signal 5.1 CH becomes low level, the strobe becomes the signal composed
through decoding.
The shift control of direct mode and digital sound field mode: AV310T（RU）has direct mode and
digital sound field mode, its strobe input is controlled by N111 CD 4052 and N102 CD 4053.
When signal 4053-INT becomes high level, the IC is out of working status as it is connected to the
emarginated terminal of N102, thus the main channel signal is output through Pin 6 and Pin 11 of
N111, and directly transmitted to the hi-fi music signal processed by M62446. When 4053-INT
becomes low level, the main channel signal is transmitted to decoding board for digital sound
process, while N102 is still under working status.

2. The signal process of Karaoke
After the signal of Karaoke transmitted from M-board is amplified in coupling amplifier, it is
directly transmitted to Volume and Key Control IC PT 2315 for processing, after the reverberation
delay is adjusted in PT2399, it is transmitted through band pass filter to loudspeaker for
small-signal amplifying. As PT 2315 is controlled by CPU, the user may adjust it through the
remote controller as they like.
While the other signal, after being amplified and rectified, is used to control the switch triode
V201 9014 and in turn to control the high level and low level of the Test Signal P-KT to test
Karaoke signals. When the input Karaoke signal is strong enough to lead the direct current
rectified to triode 9014, and to lower the P-KT signal, which indicates the input of Karaoke signals.
When the system is unable to detect signals in a certain period of time, the system will
automatically becomes soundless in the section of Karaoke and prevent the outside noise from
affecting the audio effect.

3. The switch-on of fan
When the amplifier is loaded, given that the power increases and the temperature raises fast, the

power amplifier equipped with fan for heat radiating. When volume is bigger than 45 DB, the
signal of fan becomes high level, V103 and V105 becomes electrified and forms a circuit to switch
on the fan. But when the earphone is loaded, the control line PH-SW becomes high level, then
V104 becomes electrified and lowers the signal of the fan, consequently, no matter how high the
system volume is, the fan will not be switched on.

III. Decoding Board

The main components of the decoding board are listed as follows:
CPU: the controlling core of the power amplifier
IC 493264：the high-performance digital audio decoder, including DOLBY decoding, DTS

decoding and DSP processing.
IC 8415: Serial audio digital signal receiver
IC CS5340：2-channel A/D shift
IC CS 4360：6-channel A/D shift
IC 24C02：status saving
IC 74HC04：multiplex (MPX) inverter
IC BM1117-3.3：3.3V stable voltage IC supplying power to CS8415, CS4923

Working Principle

After the fiber and coaxial signal go through the inductance filter and capacitance filter, it will be
inverted in the inverter and then transmitted to Pin 4, Pin12 and Pin 14 of the serial audio digital
signal receiver IC CS8415, through this IC, the serial audio digital signal is transformed into PCM
signal and output through Pin 16(sampling rate signal), Pin 17(main channel clock signal) and Pin
18(audio data signal) to Pin 25(sampling rate control signal), Pin 26(clock signal) and Pin
22(PCM data input interface 1) of the digital audio decoder IC CS4923, and the data will then be
processed.
After the signal of the simulated right and left channels signal is transmitted through Line XS17 to
decoding board for small-signal pre-processing , it will be transmitted to Pin 10 and Pin 12 of IC
CS5340 for A/D shift, turning the simulated audio signal into PCM signal, and then transmitted
from Pin 4(audio PCM signal), Pin 17(sampling rate signal) and Pin18(clock signal) of CS5340 to
Pin 27, 28 and 29 of CS 4923, i.e. it is transmitted to the other PCM interface of CS4923 for data
processing.
In consequence, the digital sound field processing of simulated signal and the coaxial and fiber
processing are relatively independent, if either of the processing does not work, the problem will
more probably occurs before CS4923.
CS4923 has the function of digital sound field processing, within which DSP processing, PROH
processing and DOBLY/AC-3 processing takes place through the CPU.
The audio PCM signal processed by CS 4923 is transmitted to CS4360 for D/A shift, turning the
PCM signal back to the 6-channel simulated signal, then it filters the noise beyond the frequency
range in the band pass filter, finally it is transmitted to input gating section for choice input.
As the core of the whole machine, CPU is of vital importance. Through it, all control signals
controls the actions and continuously check different signals and the user’s orders to control the
action of every part of the machine. In case the CPU is of bad quality, the whole machine will not
be able to work properly.
In addition, this machine does not have the automatic searching function; instead, it will

automatically save and memorize the last working status and the first working status after the

n

machine being switching on.
This machine is qualified with radio function, offering the users a variety of function choices. It
receives the frequency signal through the radio head controlled directly by CPU and outputs the
signal after being amplified through power amplifier. The radio head and LM62446 share the
clock and the data line, while the other control lines are directly connected to CPU, and the L and
R signals processed by the radio head are directly transmitted to the pre-amplifier for strobe input.

Ⅳ.Control Board

The control board mainly consists of VFD display, driver IC PT6311and remote receiver
HSOO38A2 and signal lamp video circuit. It mainly assumes the task of man-computer dialogue
and working status revelation.

Diagram:

Under the control of CPU: the DST status, DCK clock and DDA data control PT6311 to show the
working status of the whole machine, in receiving the user’s orders, they control the circus of the
whole machine, enabling the whole machine to work in a designated status.
When the users operate the board buttons, the order of control is transmitted to PT6311 through
the keyboard scanning circuit; while PT6311 is driven through encoding in the inner, and outputs
the control data to CPU, which in turn control the circuit and VFD through PT6311.
VFD101is a vacuum fluorescence display screen, it is highly characterized by high light. Its
working principle is similar with the picture tube of televisions. Pin 1, 2, 46 and 47 supply power
for the filament of the bulb; CPU ultimately controls SEG polar through its control over PT6311,
enabling the characters appropriate with the working status to be revealed on the screen.
The remote receiving circuit is mainly composed by remote control receiver HS0038A2, among
which Pin 1 is connected to the ground, Pin 2 supplies the power and Pin 3 outputs the received
signals and leads them to CPU to control the appropriate circuit.

V. Po w er B oa r d

The function of power board is to supply a variety of working voltages needed by the unit circuit

VFD

Display

Control Butto

U401

PT6311

Signal Light Control Area

DDA
DCK
DST

CPU

Remote

Receiver

of the whole machine. AV310（RU）applies a annular transformer of 335W. The Central Channel

p

r

r

r

N

r

r

r

and surround channel of AV310（RU）adopt LM1875 and LM4731 respectively, and LM4731 is
amplified IC powered by dual channels, which adopts independent positive power source to
supply electricity, enabling a high separation between the two surrounding channels; Compared
with the previous products, it adds ±VSS power supply, which is illustrated as follows:

1. The two alternating currents of 38V firstly transmitted from the transformer are filtered and
rectified through the four IN5404 and the two electrolysis condenser 15000uF/68V, and then the
±53V power is obtained for power supply of the right and left channels.

2. The two alternating currents of 21V secondly transmitted from the transformer are filtered and
rectified through the four IN5404 and the two electrolysis condenser 47000uF/35V, and then the
±28V power is obtained for power supply of Channel SL/SR/C. In addition, the other ICs and
collinear amplifier supply its IC with powers obtained through regulation from the regulator tube
L7812 and L7912.

～26V

Board
Display
Screen

～220V50HZ

～38.5

Rectifica

V

-tion
filte

R

ectifica

-tion
filte

～2.2V

Filament voltage

Dual-channe
l powe
amplifier

～16.3V

egative feedback

R121,R108,C105

compound amplifie
V132，V112

C,SL,SR
channel

ower

amplifier

L IN

V101
V115
mute

Differential
amplifier

constant current source
circusV104,V107,VD102,VD1

Voltage Ampl
stageV105

ifie

.

Temperature compensatio
stage V106

compound amplifie
stage V133，V113

Relay

Louds
oeake

r