BBK AV215T Service Manual

Principle, Knowledge and Maintenance of

AV215T (RU)

Contents

Chapter One Product Description Chapter Two Operating Principle

Section One Overall Structure Section Two Volume Board Section Three Signal Processing Board Section Four CPU Board Section Five Control Panel Section Six Power Panel Section Seven Power Amplifier Board and Protection Circuit

Chapter Three Maintenance Process

Chapter One Product Description

AV215T (RU) is an advanced power amplifier with complete functions that adds LCD to its predecessor as well as 16 kinds of spectrum displays in the sky-blue background which makes it more extraordinary. The radio reception makes this type of device the best choice for users who are fond of radios. Its main features are as follows:

1. Built-in 5-track power amplifier that can adapt to AC-3/DTS and stereo music playback. It is powerful with 80W main channel and 15W centre surround sound.

2. Mixing input interface of AC-3/DTS, VCD and DVD and DBB and stereo output interface.

3. 6-channel volume control and independent level control as well as 7-band EQ.

4. Bass Enhancer system, cyber logic and Hi-Fi playback.

5. One button for movie, music and karaoke.

6. Multiple EQ modes that adapt to different music styles.

7. Automatic spectrum analysis and compensation, automatic signal compensation.

8. Multiple spectrum display modes.

9. Complete karaoke function including microphone independent volume control, overall volume control, pitch adjustment, voice compensation, delay and echo adjustment as well as the newly added earphone output.

10. Karaoke wide sound field function.

11. T uning function.

12. Intelligent protection of over-current and over-voltage.

Chapter Two Operating Principle

Section One Overall Structure

AV215T (RU) mainly consists of the following seven parts:

I. Volume Board: Select input signal source, cyber logic and bass enhancer. II. Signal Processing Board: Karaoke signal processing and 5.1CH signal

amplification. III. CPU Board: Overall control, frequency point gating, automatic circuit search. IV. Control Panel: LCD display, remote control keyboard and backlight display. V. Power Panel and Protection Circuit: Provide operating voltage required by unit

circuits and overall protection. VI. Power Amplifier Board: Power amplification of 5.1CH signal or analog signal. VII.

AV215T (RU) has four input modes: Radio input, VCD, DVD and 5.1CH. The cyber logic function of AV215T (RU) is to get C/SR/SL/SW track signals by sampling from L/R track and then processing through low-pass filter and adder subtractor. Mode

Tuner: Receive radio signal and send to amplifier for signal-processing.

Section Two Volume Board

switch is achieved by using electronic analog switch. The signal flow chart is as follows:

Tuner

VCD

DVD

5.1CH

CD405

Electronic

switch

N101

S-C

S-SR S-SL

107B

105B

105A

L R

104A

CD 4053

Electro nic switch

OUT

N106

M62446

104B

107A

SWIN

S-C

4053

Electro nic switch

103

Input selection and sound field processing mode

The input selection of AV215T (RU) is achieved via electronic switches CD4052 and CD4053, the truth tables of which are as follows:

CD4052 Truth Table CD4053 Truth Table Tuner VCD DVD 5.1 A X B Y C Z A 0 0 1 1 0 X0 0 Y0 0 Z0 B 0 1 0 1 1 X1 1 Y1 1 Z1

108B

DISPLY

5.1CH input mode: Now A/B/5.1CH control pins of M62446 are of high level. L/R

track signal of 5.1 input is outputted from pin 3/13 of N101 and sent to IC N106 for volume and tone adjustment; meanwhile, C/SR/SL signal on 5.1 input terminal is respectively sent from pin 14/15/4 output of N410 to IC N106 for independent volume adjustment. And SW signal is outputted via pin 4 of N103 and then send to M62446 after being amplified by N107A. Three analog input modes: AV215T (RU) totally has three analog input modes: Tuner receiving signal/VCD/DVD, which are controlled via A/B signal respectively (see details in truth tables). AV215T (RU) totally has three sound field modes: standard sound field, cyber logic and Hi-Fi.

1. Standard sound field: Under overall CPU control, when bass enhancer is off, L/R

channel and subwoofer output are available; when bass enhancer is on, only L/R channel output is available.

2. Hi-fi: Under overall CPU control, only L/R tracks output is available to M62446;

3. Cyber logic:

Pin 9/10 of electronic switch N101 (CD4052) select a series of analog L/R track input signals according to the truth table. L/R signals are outputted from pin 13/3 via the internal electronic switch of N101, and divided into two ways. One way is respectively sent into pin 13/15 of M62446, for electronic volume and tone control. The other way produces SW/S-SR/S-SL/S-C signals via buffer, adder-subtractor and low-pass filter. SW/S-SR/S-SL signals are sent to pin 12/2/5 of N102. N102 select cyber logic signal input (see truth table of CD4053) from cyber logic and

5.1CH signals, outputs C/SR/SL signals and sends into pin 11/8/9 of M62446 for volume control. Still another way of SW signal directly sends to pin 6 of M62446 after being outputted from N107A. 5.1CH signal sent into M62446 is outputted from pin 31-36 after volume and tone control, and then outputted to signal board

by XS20 power distributor. The relation between sound sources in input circuit and sound processing modes is as illustrated below.

II. Control circuit

Pin 23/26/27 of CPU (N100) output data, PVST and clock signal and send to pin 39/40/41 of M62446 to control pin 1/2/3/4 of M62446 to output control level, so as to select input signal and spectrum sampling signal. It is worth noting that PVST signal is a latch control signal. When data and clock of CPU are sent to M62446, an identification signal will be added, indicating that this signal can only be used by M62446 while other IC of I2C bus cannot use current data and clock signal.

eld

Hi-fi mode

Press INPUT

utton to circularly select

Two analog input modes

Standard sound fi

Cyber logic

5.1 inpu mode

III. Frequency spectrum sampling circuit

Only S-C/S-SR/S-SL/SW signals are sampled during frequency spectrum sampling in AV215T（RU）and added to pin 14 via a 150K sampling resistance. Another S-C cyber logic signal is added to pin 1 of N103, called S-C. 5.1CH and LR-T of M62446 select sampling signals. When cyber logic is selected, the control signal of 5.1CH is of low level while pin 9/11 of N103 is of low level. According to the truth table, it is known that the outputs are X0/Z0. Sampling signal is grounded while LR-T is of H level. Select Y1, S-C＇signal is outputted from pin 15 of N103 to N108B, adding to OK-R signal for the amplification of frequency spectrum signal, and then sent to frequency point gating and auto search circuits.

. Ⅳ Tuning function

This device has the tuning function which provides users a good functional option. It directly controls radio-head and receives audio frequency signal mainly via CPU and then outputs after amplified via power amplifier. The clock and data line of radio-head are shared with LM62446 and the other two control lines are connected to CPU directly. L, R signal processed by radio-head can be sent to N101 IC CD4052 directly to input the selected track.

L/R channel output only. Soun filed and EQ setup not available.

L/R/SW output only. Concer hall sound filed and EQ setup available

6CH output. Theater sound file and EQ setup available

Section Three Signal Processing Board

The signal processing board superposes, mixes and amplifies 5.1CH signal sent from the volume board, voice signals from the voice board and karaoke signal.

I. AV215T（RU）Karaoke Circuit

1. Function: this circuit processes human voice through power amplifier and reproduces it via speaker. It includes human voice beautification circuit, wide sound field processing circuit, karaoke echo and delay adjusting circuit.

IC and its functions for karaoke

IC serial

number N201 4558 Transmittal. Preamplification for karaoke signal N200 PT2315 Volume control of karaoke, including tone control N205 CD4053 Electronic switch N209 PT2399 Karaoke echo processing N207 CD4051 Karaoke delay adjustment N208 CD4051 Karaoke echo control N204 4558 Phase inverter

PT2315 functional pin

S/N Name of pin Description Remarks 1 REF Reference voltage (1/2VDD) 2 VDD Power supply 3 AGND Analog 4 TREB L 5 TREB R 6 RIN R channel input 7 LOUD-R R channel loudness control pin 9 LOUD-L L channel loudness control pin 11 LIN L channel input 12 BIN L 13 BOUT L 14 BIN R 15 BOUT R 16 RFOUT R channel output 17 LFOUT L channel output 18 DGND Digital 19 DATA （DATA）control data of sequence

20 LCK Clock input of sequence

8，10 NC Not connected

3. Flow chart of karaoke signal

Name of IC Functions

L/R channel treble control pins

L channel bass control input/output

R channel bass control input/output

transmission (DATA)

transmission

MIC

201

200

202

203B

209

N205

204

202

207

100

V200

208

Karaoke mixed output

When the microphone is inserted, MIC signal is sent via MIC to the transmittal circuit combined by N201A for amplification. Amplified MIC signal gives CPU a MIC identification signal after N202A amplification, followed by VD201 rectification and filtering control triode V200. CPU sends PKM signal, which is of low level, causing cutoff of triode V103/V105 and enabling output of MIC signal; another way reaches pin 6/11 of PT2315 after C219/C222 coupling, outputs from pin 16/17 after internal volume and tone control, mixed into one way and sent to N202B and then reversely send to N203B for amplification. Signals amplified by N203B are divided into two ways. One way is directly outputted. The other way is outputted from pin 14 after being coupled by R222/C247 to PT2399 for internal delayed reverberation adjustment, reversed by N204 and outputted by mixing with karaoke signal. While OK-R is outputted from pin 14 after being gated by N205 and superposed to L/R track.

In this circuit, the bass boost network made up of triode V201 connected to the negative terminal of N202B is primarily for bass boost of 75HZ low frequency signal.

During delay adjustment for PT2399, first control signal is given to CPU, which controls N207 after being expanded via N211 IC CD4049 and connects with pin 6 of PT2399 by selecting different resistance values for purpose of delay adjustment.

Reverberation control is to change the resistance value at the connection point to R229, so as to change the superposition on through connect signal for reverberation control.

The broadband processing control signal of SOK’s karaoke is in broadband mode when it is of high level, when the signal of OK-R is the OK signal inverted by N204A.

A sense signal of OK-SW on the MIC plug conducts MIC signal detection together with the network made up of V200. When MIC is not plugged, it is of low signal; when plugged, it is of high signal.

Karaoke auto mute is also available. When P-KT fails to detect signal for a continuous time, CPU will send a P-KM signal to mute karaoke and avoid MIC receiving noise, which may affect on sound effect.

 Signal flow chart of profiles

Pass

AV215T (RU) has a special function that switching between 5 profiles is available

without karaoke. Its flow chart is as follows:

204

205

203

209

204

Mixed output

207

208

CD4094

When pin 9/10 are of high level, sampled L/R/C signals are outputted via pin 3 N205 gating, and sent to the internal of PT2399 after amplification by N203B for reverberation delay adjustment (by IC CD4049), and then superposed to L/R/C track to form different profiles.

In this circuit, MIC shall not be inserted and is only available in 5.1CH mode. N203A

is for the purpose of reversal.

In addition, this device is added earphone output function. PHSW is low level and each track has output when earphone is not inserted. But when earphone is inserted, PHSW will be high level for the mechanical settings thus LRM and SCM signal change into high level at the same time and realize muting in each track, so the signal is only outputted from earphone, i.e. there is no signal output with each track when connecting with earphone output.

II. Bass enhancer circuit

P-BURST is the switch signal of burst driver. When it is of high level and added to the base electrode of V102, V102 will be switched into conduction. When the collector electrode outputs low level, V107 will be cut off; when the collector electrode is of low level, V107 will also be cut off. SW signal is normally outputted to external terminal. Meanwhile, the high level signal of P-BURST is added to the emitter electrode of V108. V108 is positively biased and switched into conduction. The collector electrode adds high level to the base electrode of V101. V101 is positively biased and switched into conduction,

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