BBK Innovation Sub 5.1 SERVICE MANUAL

Principal and Maintenance of INNOVATION 5.1 SUB

1. Brief introduction to product

INNOVATION 5.1 SUB is a medium grade active loudspeaker that comprised of one sub-woofer and two fronts, two
surrounds and one center. If it is positioned in a favorable room, you will enjoy its excellent sound effects. Its main
features are as follows:

1. 2.1/5.1 channel output with synthesis decoding

2. Built -in 5.1 channel power amplifier, applicable for AC-3/DTS and stereo music playback

3. 6 channels volume control and sole power control and tone adjustment

2. Block diagram of Machine ’s principal

3. Structures of machine

This set is composed of input board, output board, amplifier board and panel control. In the Input board, two
channels select IC CD4053 to finish synthesis decoding and output board is formed only by several ports. The main
component of this set is amplifier board which controls the machine and also contains amplifying component and
power supply. Following will make a simple analysis on the principal of amplifier board.

1) Power supply
This set is powered by a toroidal transformer due to large output power of its sub-woofer. Two group of alternating

currents outputting from transformer will output ±16V and ±26V voltage after commutating and wave filtering to
TDA7265and IC TDA7296.
Passing through current limit resistor R143, stable voltage IC LM7805 and capacitance C108, the outputted +16V

will output +5V voltage to CPU and panel control; another current ±26V voltage, after passing through R120、R117
and R118, two 9.1V stable diodes VD109 and VD110, then output ±9V voltage and supply power to volume
adjustment IC LC75347 and play IC F4558; ±6.8V is obtained after ±9V voltage is partially pressed by
R119、R122 and R120、R121, ±6.8V is the selected power for IC 4053.

2) Synthesis decoding circuit
This set has function of synthesis decoding. When the inputting signal is of 5.1, through channels of X0、Y0、Z0

selected by N104 & N105 , transmit to IC LC75347 where to adjust volume. This function is controlled by the 9th,
10th, 11th pin of N104 and 105 which is transmitted logic high level by the 7th pin of CPU.

Select input signal

5.1CH
Synthesis decoding

2CH

CPU machine control

and tone adjustment

Electronic volume

Power amplifier

Receiving and displaying

Signal output

When the inputting signal is 2.1 which passes through N104 and then arrives channel X1 and Z1, one of it is sent
directly to IC LC75347 and adjust volume.
Another one abstracts signal from channel L & R to make synthesis decoding, N102 and N103 shall finish the
function of synthesis decoding. When abstracting signal from channel L and R, then input via the 6th pin of N102B
and 2nd pin of N102A, SL and SR signal are obtained by mixture and amplifying of signal L and R, after resistance
sampling of SL, SW signal is obtained, C signal is received after N103A mixes and amplifies SL signal, after getting
these synthesized signal SL, SR, C, SW, select output of channel by software-controlled IC CD4053 and send the
outputting signal into IC LC75347 to adjust volume. At this step, the synthesis decoding is finished.

3) Signal output and adjustment of volume & tone
This machine has 6 channels signal input, signal inputted by each channel is directly transmitted into IC LC75347 to
adjust volume and tone after wave filtering and capacitating.
IC LC75347 is 6 channels IC to adjust volume and tone solely, its grain can be adjusted from 0—95dB, which is
applicable for family theatre series products. Its features include large scope of power supply, low power
consumption and wide range of temperature, so it is a preferable IC. Its main per-pin functions are as follows:

Name of Per-pin Number of Per-pin Description of Per-pin

FLIN 7 signal input

FRIN 24 signal input

RL 20 signal input

RR 18 signal input

C 22 signal input

SBW 16 signal input
FLOUT 9 signal output
FROUT 10 signal output

COUT 11 signal output
RLOUT 12 signal output
RROUT 13 signal output

SBWOUT 14 signal output

VREF 23 basic voltage

VDD 37 power supper

CE 40 selected signal control line

DI 39 data control line

CL 38 clock control line

MUTE 35 outer mute control

Equivalent circuit of this IC internal unit:

4) Amplifier circuit
Principal: signal outputted from IC LC75347 of which main channel signal is sent to N181 IC TDA7265 to amplify
its power, the surround signal is transmitted to N180 IC TDA7265 for amplifying after wave filtering, and the
sub-woofer signal is sent to N183 IC TDA7296 after wave filtering.
IC TDA7265 is a dual channels power amplifier IC which has stand-by and mute modes without any trouble in
switching, and it also has functions of short circuit protection and over heat protection that can effectively prevent IC
from damage under abnormal situation. This IC may provide the maximum 20W power output in each channel based
on common output mode, when switching on BTL output, its power can reach 40W, and in addition, this IC has s
strong ripple resistance capability and low power consumption during stand-by.
Per-pin functions of IC TDA7265 are as follows:

Mark sign per-pin function

-VS 1 negative power

OUT1 2 1st channel output

+VS 3 positive power

OUT2 4 2nd channel output

MUTE 5 mute control pin

-VS 6 negative power

IN+2 7 2nd channel input

IN-2 8 2nd channel input

GND 9 ground

IN-1 10 1st channel input

IN+1 11 2nd channel input

However, IC TDA9296 is a single channel power amplifier IC; it has similar features as that of IC TDA7265,
however, its output is more powerful, the single channel may reach 35W.

5) Control circuit
This machine uses IC AT89C2051 as its core part to control its operation. This IC is a low voltage and high-powered
IC which is equipped with 8 digits USB of 2K byte and read-only memory Single Chip Micyoco (SCM) based on
CMOS technique. It has 15 I/O and 6 interrupt sources and features in low power consumption and stand-by mode.
The principal block diagram of this IC is as follows: