BBK AV225T Service Manual

AV225T

service manual

Catalog

Chapter One About Maintenance

1.1 Safety precautions

1.1.1 Power supply

1.1.2 Precautions for antistatic

1.1.3 About placement position

1.2 Maintenance method

1.2.1 Visualized method

1.2.2 Electric resistance method

1.2.4 Current method

1.2.5 Cutting method

1.2.4Currentmethod

1.2.5Cuttingmethod

1.2.6 Element substitution method

1.2.7 Comparison method

1.3 Required device for maintenance

Chapter Two Operation Instructions

2.1 Control button locations and explanations

2.1.1 Front panel illustratlons

2.1.2 Rear panel illustration

2.1.3 llustrations to the

2.2 asic operations remote control

2.2.1 urn on/off this unit

2.2.2 tp function

2.2.3 Select Input Sound Source

2.2.4 Bass Enhancer

2.2.5 Select Sound Field

2.2.6 Adjust Volume

2.2.7 Adjust Level

2.2.8 EQ function

2.2.9 Parameter Processing

2.2.10 Adjust Karaoke

2.2.11 Tuning Function

2.2.12 Other Operations

Chapter Three Principle and Servicing

Section One Principle of the Player

3.1.1 Composition of the player

3.1.2 Function and features

3.1.3 Player block diagram

3.1.4 The player signal flow chart

Section Two Unit Circuit Principle

3.2.1 Volume board circuit

3.2.2 Signal processing board circuit

3.2.3 MCU board circuit

3.2.4 Control panel circuit

3.2.5 Power board circuit

3.2.6 Power amplifier board and protection circuit

3.2.7 MIC, headphone board

3.2.8 Video in/out board circuit

Section Three Servicing Cases

3.3.1 Servicing instances

3.3.2 Troubleshooting process

Section Four Servicing Parameters

3.4.1 Signal waveform diagram

3.4.2 Key point voltage

Section Five Function Introduction to IC

3.5.1 function introduction to 4558

3.5.2 function introduction to Pt2399

3.5.3 function introduction to Cd4051

3.5.4 function introduction to Cd4052

3.5.5 function introduction to Cd4053

3.5.6 function introduction to Sm79164

3.5.7 function introduction to Pt2308

3.5.8 function introduction to Pt2222

3.5.9 function introduction to Lm1875

3.5.10 function introduction to TDA7265

3.5.11 function introduction to M62446

3.5.12 function introduction to AT24C02

3.5.13 function introduction to L7805

3.5.14 function introduction to 7812

3.5.15 function introduction to 7912

3.5.16 function introduction to LM324

3.5.17 function introduction to Pt2315

3.5.18 function introduction to 74VHC245

3.5.19 function introduction to Cd4094

Chapter Four Disassembly and Assembly Process

Chapter Cinque PCB board & Circuit diagram

Section One PCB board

Section Two circuit diagram

Chart 6 BOM List

6.1 olume board

6.2 olume board ai segment

6.3 ignal disposal board

6.4 ignal disposal board ai segment

6.5 pu board

6.6 pu board-smd

6.7 mplifier board

6.8 urface control board

6.9 ideo input output board

6.10 Microphone holder board

6.11 ower board

6.12 emote coneroller

6.13 anel units

6.14 ofeware program

105

106

108

110

111

112

116

117

118

120

121

6.15 n lasel

6.16 Supplement module

121

ChapterOneAboutMaintenance

1.1Safetyprecautions

1.1.1Powersupply

Whenservicingaudiopoweramplifier,theservicingpersonnelpayspecialattentiontothepower boardwith220VAC,orelsetheimproperoperationwillleadtobodydamage.Thealternatecurrent whichoutputstopoweramplifierboardthroughpowerboardisalsouptovoltagewithabout50V;when servicing,short-circuitandjointweldingcannotoccur,orelsetheelementswillbeburntoutandtrouble rangewillbeenlarged.

1.1.2Precautionsforantistatic

Movementandfrictionwillbothbringstaticelectricitywhichcausesseriousdamagestointegrated IC.Thoughstaticchargeislittle,whenalimitedquantityofelectricchargeisaddedtolargescaleintegratedIC,asthecapacitanceisverysmallinthemeantime,nowtheintegratedICisverymuch easytobestruckthroughbystaticelectricityortheperformancewilldecrease.Thusstaticelectricity preventionisofextraordinaryimportance.Thefollowingareseveralmeasurestopreventstatic electricity:

1.Useapieceofelectricconductionmetalwiththelengthofabout2metrestoinsertintotheearth, andFetchtheleadwirefromthetopofthesurplusmetalandconnecttotherequiredstaticelectricity device.Thelengthanddepthofthemetalembeddedundertheearthshouldbedeterminedaccordingto thewettabilityofthelocalsoil.Forhumidplaces,itmaybeshorter,andlongeranddeeperfordryplaces. Ifpossible,itcanbedistributedandlayedintermsof“#”shape.

2.Onoperatingtable-board,theantistatictablecushionshouldbecoveredandgrounded.

3.Alldevicesandequipmentsshouldbeplacedontheantistatictablecushionandgrounded.

4.Maintenancepersonnelshouldwearantistaticwristringwhichshouldbegrounded.

5.Placesaroundtheoperatingpositionshouldalsobecoveredwithelectricconductioncushionor Paintedwithantistaticpaint.

-1-

1.1.3Aboutplacementposition

Audiopoweramplifiercannotbeinstalledinplaceswithhightemperatureandhumidity.

2.Positionsforplacementshouldbestableandsecure.

1.2Maintenancemethod

1.2.1Visualizedmethod

Directlyviewwhetherabnormalitiesofcollision,lackofelement,jointwelding,sheddingwelding, rosinjoint,copperfoilturningup,leadwiredisconnectionandelementsburningupamongpinsof elementsappear.Checkpowersupplyofthemachineandthenusehandstotouchthecasingofpartof elementsandcheckwhethertheyarehottojudgethetroublespot.Youshouldpaymoreattentionwhen usingthismethodtocheckinhighvoltageparts.

1.2.2Electricresistancemethod

Setthemultimeterinresistancepositionandtestwhetherthenumericalvalueofresistanceofeach pointinthecircuithasdifferencefromthenormalvaluetojudgethetroublespot.Butinthecircuitthe testednumericalvalueofresistanceisnotaccurate,andthetestednumericalvalueofintegratedIC's pinscanonlybeusedforreference,sotheelementsshouldbebrokendownfortest.

1.2.3Voltagemethod

Voltagemethodisrelativelyconvenient,quickandaccurate.Setthemultimeterinvoltageposition andtestpowersupplyvoltageoftheplayerandvoltageofacertainpointtojudgethetroublespot accordingtothetestedvoltagevariation.

1.2.4Currentmethod

Setthemultimeterincurrentpositionandtestcurrentoftheplayerofacertainpointtojudgethe troublespot.Butwhentestingincurrentmethod,themultimetershouldbeseriesconnectedinthe circuit,whichmakesthismethodtootrivialandtroublesome,soitislessfrequentlyusedinreality.

1.2.5Cuttingmethod

Cuttingmethodshouldbecombinedwithelectricresistancemethodandvoltagemethodtouse. Thismethodismainlyusedinphenomenaofshortcircuitandcurrentleakageofthecircuit.When cuttingtheinputterminalvoltageofacertainlevel,ifvoltageoftheplayerrisesagain,itmeansthatthe troubleliesinthislevel.

-2-

1.2.6Elementsubstitutionmethod

Whensomeelementscannotbejudgedgoodorbad,substitutionmethodmaydeadopteddirectly.

1.2.7Comparisonmethod

AsamegoodPCboardisusuallyusedtotestthecorrectvoltageandwaveform.Comparedthese datawiththosetestedthroughfaultPCboard,thecauseoftroublesmaybefound.

Throughtheabovemaintenancemethod,theoreticalknowledgeandmaintenanceexperience,all difficultiesandtroubleswillbereadilysolved.

1.3Requireddeviceformaintenance

AudioGenerator

◆

Digitaloscillograph(100MHE)

◆≥

SMDreworkstation

◆

Multimeter

◆

Solderingiron

◆

Pointed-monthpincers

◆

Cuttingnippers

◆

Forceps

◆

Electricscrewdriver

◆

Terminalsconnectingcord

◆

Headphone

◆

Microphone

◆

-3-

Chapter Two Operation Instructions

2.1 CONTROL BUTTON LOCATIONS AND EXPLANATIONS

2.1.1 FRONT PANEL ILLUSTRATLONS

POWER SWITCH Power on/off this unit

LCD Screen Buttons operation indication and spectrum display when working

IR sensor Receive the infrared signals transmitted from the remote control

MASTER VOLUMEPress this button to synchronously lower all 6CH volumes

INPUT Sound source input button

MIC VOLUME+ Press this button to increase the volume of MIC

MIC VOLUMEPress this button to lower the volume of MIC

TUNING Select other frequency radio stations upwards

Tuning Select other frequency radio stations downwards

BAND Select FM/AM tuner BAND

PRESET Select the latter preset radio station

PRESET Select the previous preset radio station

MODE Select tuner mode:manual/auto

MASTER VOLUME+ Press this button to synchronously increase all 6CH volumes

STANDBY Standby

COVER OF PHONE JACK AND MICROPHONE JACK

- 4 -

2.1.2 REAR PANEL ILLUSTRATION

AC-3/DTS 5.1CH INPUT

5.1CH audio signals input terminals that connect to DVD, AC-3/DTS

AM/FM antenna terminal

Connect AM/FM antenna outside

Stereo Audio jack

The terminals that connect with VCD, DVD stereo audio signals input

Video input

The terminals that connect with VCD,DVD Video signals input

Video output jack

The terminals that connect with TV Video signal output

Data The data plate of this unit

SERIAL NO. Mark

The manufacturing records

CAUTION mark

Remind the user of dangerous voltage inside

Line-out

Subwoofer signals line-out jack

This unit's manufacturer

Terminals

Connect with SPEAKER terminals

2.1.3 ILLUSTRATIONS TO THE REMOTE CONTROL

STANDBY button: Power on, STANDBY switch button

DISPLAY button: Select audio spectrum display modes

MUTE button: Mute On/Off button INPUT button: Select input signal sources manually

MOVIE button: OTP button to set standard movie

theater surround mode

MUSIC button: OTP button to set standard concert mode

K.R.OK: OTP button to set standard Karaoke mode

HI-FI button: Select the Hi-Fi sound field

STANDARD button: Select the standard sound field

CYBER LOGIC button: Select the cyber logic sound field

BASS ENHANCER button: Select the bass enhancing effect

Number buttons 1~8: Select 8 preset working modes with the help of SAVE/CALL button, capable of storing and calling the user-set working mode parameters

SPEAKERS button: Adjust the separate channel level with the help of / keys

CHILD LOCK button: Lock the functions of the front panel controls

SURR. Button: Select the surround sound field

DEFAULT button: Restore the factory default settings

SAVE button: Store the current working mode parameters with the help of number buttons 1~8

CALL button: Call the user-stored working mode parameters with the help of number buttons 1~8

EQ select button: Select the equalization frequency

MULTI-BAND EQ button:Adjust multi-band electronic equalization

Adjust button: Adjust level and multi-band EQ

EQ button: Circularly call the preset EQ modes AUTO EQ button: Analyze the current signal spectrum,

automatically set EQ parameters

- 5 -

VOLUME button: Adjust the karaoke level with / keys

ECHO button: Adjust the karaoke ECHO with / keys

VOICE MODIFY: MODIFY button: Select Karaoke voice modify WF button: Karaoke wide sound field On/Off

TONE button: Adjust the karaoke BASS/Treble tone levelwith / keys

DELAY button: Adjust the karaoke delay time with / keys

MASTER VOL button: Synchronously increase/decrease 6 channels' volume

BAND button: Select FM/AM tuner band

MODE button: Select tuner mode:manual/auto

STEP button: Select AM tuning step:9K/10K

MEMORY button: Memory the received radio station with the help of number buttons 0~9 CLEAR button: Clear the preset radio station with the

help of number buttons 0~9

TUNING : Scan other frequency radio station upwards

TUNING : Scan other frequency radio station downwards

PRESET : Select the latter preset radio station

PRESET : Select the previous preset radio station

NUMBER 0~9 :Save the received radio station programs or directly call the preset programs with the help of MEMORY button

2.2 BASIC OPERATIONS

2.2.1 TURN ON/OFF THIS UNIT

Please check the connection cords before turning this unit on. If all connections are correct, you can connect this unit to power.

Press the POWER button, this unit enters the standby mode .

When this unit is in the standby mode, it detects the input signals automatically.

When there is signal input, this unit turns on automatically.

When the input signal is too small, this unit might not detect the signal and will not turn on automatically.

When there is signal input and the unit cannot turn on automatically, press the STANDBY button on the front panel or remote control to operate manually and select input signals by using the INPUT button.

When the unit is in the standby mode, press the STANDBY button on the front panel or remote control to turn on this unit.

Press the STANDBY button on the front panel or remote control.

After turning on this unit, it detects the input signal automatically. When there is signal input, it receives the input signal automatically. Otherwise, the unit will automatically search signals all the time.

When there is signal input but it cannot receive

The signal automatically, press the INPUT button on the remote control to select the input signal.

When the unit is in normal working mode, press the STANDBY button on the front panel or remote control if you want to enter standby mode.

Please turn off the power when you are not going to use the unit for a long time.

Please turn off the power every time after you

use the unit.

Press the " POWER" button on the front

panel to power off this unit.

POWER

2.2.2 OTP function

We have set the OTP function to simplify the

operation of testing sound effects.If the played

disc is movie or story, you just press the MOVIE

button and the system will automatically set

standard movie mode.If the played disc is music,

you just press the MUSIC button and the system

will automatically set standard music mode.If

you want to sing Karaoke, you just press the

- 6 -

K.R.OK button after inserting microphone and The system will automatically set standard

Karaoke mode.

Press the MOVIE button to set standard

theater surround mode.

Automatically detect the input signal source. If many signal sources input, it will select the current signal input preferentially.

Automatically set the parameters of surround. If 5.1CH input signal is detected, it will automatically adopt standard mode; if 2CH signal source is detected, it will automatically adopt Cyber Logic.

Press the MUSIC button to set standard music modeAutomatically detect the input signalsource. If many signal sources input, it will select the current signal preferentially.

Automatically set the parameters when enjoying music. If 5.1CH input signal is detected, it will automatically adopt standard mode;if 2CH signal source is detected, it will automatically adopt Hi-Fi mode.

Press the K.R.OK button to set standard Karaoke mode.

Automatically detect the input signal source. If many signal sources input, it will select the current signal preferentially.

Automatically set the parameters of Karaoke mode. NOTE: If the signal is too weak or in the blank segment of music when operating, the system will probably appear wrong indications.

2.2.3 Select Input Sound Source

This unit utilizes two input lines of stereo audio sources: VCD, DVD; one line 5.1 channel signal input. Select the input signal source manually through the remote control.

Press the INPUT button on the remote control, and "INPUT TUNER" splays, which means TUNER has been selected.

Press the INPUT button on the remote control, and "INPUT VCD" displays, which means VCD 2CH input jack has been selected.

Press the INPUT button on the remote control, and "INPUT DVD" displays, which means DVD 2CH input jack has been selected.

Press the INPUT button on the remote control, and "INPUT 5.1CH" displays, which means

5.1CH input jack has been selected.

2.2.4 Bass Enhancer

In order to strengthen the low frequency of music, you may start up Bass Enhancer function.

Press the "BASS ENHANCER" button on the front panel or remote control, "BASS driver 0", “BASS driver 1 ", "BASS driver 2 " or”BASSdriver 3" will display.

- 7 -

The display "BASS driver 1-3" means the first, second and third Bass Enhancer; the subwoofer signal adds into the master channelsignal; turn off the subwoofer line output.

The display "BASS driver 0 " means turn off Bass Enhancer; normal subwoofer line output.

Bass Enhancer function cannot be started up in Hi-Fi mode.

2.2.5 Select Sound Field

1 HI-FI In 2CH signal input, you may select the Hi-Fi mode to keep the originally musical features.

Press the HI-FI button on the remote control and "HI-FI" will displays, which means the system enters the Hi-Fi mode; if "NVALID" displays, it means the system cannot enter the Hi-Fi mode.

Bass Enhancer function and operations related to EQ are invalid in Hi-Fi mode.

Pressing the HI-FI button is invalid in

5.1channel input.

Press the STANDARD button on the remote control and "STANDARD" will display, which means the system enters standard sound field.

3 Cyber Logic

In order to make 2 channel input signals have multi-channel sound field effect, you may select Cyber Logic sound field.

Press the CYBER LOGIC button on the remote control and "CYBER LOGIC" will display, which means the system enters Cyber Logic sound field: if "INVALID" displays, it means the system cannot enter Cyber Logic

Cyber Logic mode is invalid in 5.1 channel signal input.

2 Standard

In order to keep the correspondence with input signals and adjust output timbre according to personal habit, you may select the standard sound field.

4 Surround In order to cater for different listening Environments and meet different sound effect requirements of customers, you may select different surround modes in 5.1 channel signal input status.

Press the SURR button on the remote control in 5.1 channel signal source input, the surround will display.

Press the SURR button on the remote control Repeatedly; you may select the environment

- 8 -

Modes between Affectional movie, Sowordsmen movie, Gunfignt movie, Sci-fi movie and music.

The environment surround is invalid in 2-

channel signal input status.

The environment surround is invalid if

microphone is inserted.

2.2.6 Adjust Volume

1 Master Volume When the current sound is too high, too low or unsuitable, you may press the MASTER VOL on the front panel or remote control to adjust the volume of all channels.

Press the "+" button of master volume on the front panel or remote control to increase all channels' volume simultaneously; the max volume is 60.

Press the "-" button of master volume on the front panel or remote control to decrease all channels' volume simultaneously; the min volume is 0.

The master volume displays as the example: "VOL: 20”

2.2.7 Adjust Level

1 Left channel level

When sound of left and right channels is imbalance, you may adjust R channel level to make it in balance with L channel.

Press the SPEAKERS button on the remote control and "L: 00" will display. Operate as follows:

Press the " " button on the remote control to Increase the volume of L channel. The max level is +60.Press the “ " button on the remote control to decrease the volume of L channel. The min level is -60.

2 Right channel level

When sound of left and right channels is imbalance, you may adjust L channel level to make it in balance with R channel. Press the SPEAKERS button on the remote control and "L: 00" will display. Operate as follows:

3 Center level

When sound of left and right channels is imbalance, you may adjust R channel level to make it in balance with L channel.

Press the SPEAKERS button on the remote control and "R: 00" will display. Operate as follows:

Press the “ " button on the remote control to increase the volume of R channel. The max level is +60.Press the “ " button on the remote control to decrease the volume of R channel. The min level is -60. 4 Surround Left level

When sound of center channel is unsuitable, you may adjust center level to make it suitable to the sound field.

Press the SPEAKERS button on the remote control and "C: 00" will display. Operate as follows:

Press the “ " button on the remote control to increase the volume of C channel. The max level is +60.Press the “ " button on the remote control to decrease the volume of C channel. The min level is -60.

NOTE: The center level cannot be adjusted only when left and right channels have output. 5 Surround Right level

When sound of surround left is unsuitable, you

- 9 -

may adjust surround left level to make it suitable to the sound field.

Press the SPEAKERS button on the remote control and "SL: 00" will display. Operate as follows:

Press the " " button on the remote control to increase the volume of surround left. The max level is +60.Press the " " button on the remote control to decrease the volume of surround left. The min level is -60. NOTE: The surround left level cannot beadjusted only when left and right channels have output.

When sound of surround right is unsuitable, you may adjust surround right level to make it suitable to the sound field.

Press the SPEAKERS button on the remote control and "SR: 00" will display. Operate as follows:

Press the " " button on the remote control to increase the volume of surround right. The max level is +60.Press the " " button on the remote control to decrease the volume of surround right. The min level is -60. NOTE: The surround right level cannot be adjusted only when left and right channels have output.

6 Subwoofer level

When sound of subwoofer is unsuitable, you may adjust the volume of subwoofer speaker and the level of subwoofer channel to make it balanced to the sound field.

Press the SPEAKERS button on the remote control and "SW: 00" will display. Operate as follows:

Press the " " button on the remote control to increase the volume of subwoofer. The max level is +60.

Press the " " button on the remote control to decrease the volume of subwoofer. The min level is -60.

NOTE: The subwoofer level cannot be adjusted only in Hi-Fi and Bass Enhancer conditions.

2.2.8 EQ function

Due to the personal like to music, you may adjust EQ to meet your own needs. If the music tempo is not enough or full, adjust bass; if the voice is unclear, adjust middle frequency; if the musical details are not rich, adjust treble.

1 Pre-set EQ

When the sound of master volume is too weak or unclear, you may directly use pre-set EQ mode to make it accordant with the current music. This unit utilizes 8 EQ modes: Rock, Jazz, Classical, Pop, Disco, Rap and Blues.

Press the EQ button on the remote control to display the EQ curve.

Press the EQ button repeatedly to select the EQ mode accordant with the current music.

EQ mode cannot be adjusted in Hi-Fi mode. 2 Multi-band EQ

When the sound of master volume is too weak or unclear, you may set EQ mode yourself to meet you own taste.

Press the "AUTO EQ" button on the remote control to display the current EQ curve. There is a cursor flashing in the current frequency.

Press the " " button on the remote control to select the high frequency. The flashing cursor moves rightwards until the rightmost.

Press the " " button on the remote control to select the low frequency. The flashing cursor moves leftwards until the leftmost.

Press the " " button on the remote control and the current frequency level increases until the maximum.

Press the " " button on the remote control and the current frequency level decreases until the minimum.

EQ mode cannot be adjusted in Hi-Fi mode. 3 Auto EQ

When the sound of master volume is

unsuitable to you listening, you may select auto EQ.

The unit will automatically analyze the current spectrum to set the current EQ according to the current music.

- 10 -

Press the AUTO EQ button on the remote

control to display the analyzing curve.

EQ function

Auto EQ setup is invalid in Hi-Fi mode.

2.2.9 Parameter Processing

To memory the current parameter for later use, or use the defauly parameter, the Memory and Call functions will be used. The current parameters to be adjusted include: Channel Level, EQ, Bass Enhancer, Sound Field, Environment Surround, MIC Volume, MIC Treble, MIC Bass, MIC Delay, MIC Echo and Voice Modification.

1 Call Default parameter

control and "CALL 1-8" displays.

according to the default parameters. 2 Memory Parameters

first to display "SAVE "

control again under the display "SAVE "

corresponding number buttons and "SAVE 1-8" displays.

3 Call parameters

first to display "CALL "

control again under the display "CALL "

buttons before will be adopted currently and "CALL 1-8" displays.NOTE: Due to some unexpected reasons, the user-memorized parameters will probably be lost, so please adjust again and then memorize. The system will automatically check the parameter saved ast time when switching on this unit. When the

Press the number buttons 1-8 on the remote

Setup will be processed automatically

Press the "SAVE" button on the remote control

Press the number buttons 1-8 on the remote

The current parameter is memorized into the

Press the "CALL" button on the remote control

Press the number buttons 1-8 on the remote

The parameters memorized in the number

channel level is too high or too low, the system will adjust automatically

- 11 -

2.2.10 Adjust Karaoke

1 Microphone Volume

When inserting microphones to sing Karaoke, press the MIC VOL button to adjust the volume of microphonewhen the microphone voice is too high, too low or unsuitable.

Press the " " button of MIC VOL on the front panel to increase the volume of microphone The maximum volume is 30.

Press the " " button of MIC VOL on the front panel to decrease the volume of microphone The minimum volume is 0.

Press the "VOLUME" on remote control,then press " "" " to adjust karaoke volume.

The microphone volume displays as "MIC VOL 20".

The microphone volume cannot be adjusted when not inserting microphones.

2 Bass

When inserting microphone to sing Karaoke, you may adjust microphone bass when the sound tempo is not full or rich.

Press the "TONE" button on the remote control once then press" " or " " to adjust the bass of microphone. The adjustable range is 6.

The microphone bass displays as "MIC BASS +2”

The microphone bass cannot be adjusted when not inserting microphone.

3 Treble

When inserting microphone to sing Karaoke, you may adjust microphone treble when the sound is unclear.

Press the "TONE" button on the remote control twice, then press " " or " " to adjust the treble of microphone. The adjustable range is 6

The microphone treble displays as "MIC TREBL+2”

The microphone treble cannot be adjusted when not inserting microphone.

4 Echo When inserting microphone to sing Karaoke, you

may adjust microphone echo when the sound is weak or not full.

Press the "ECHO" button on the remote

control then press or to adjust the echo of

" "

microphone. The adjustable range is 0~7.

The microphone echo displays as "MIC ECHO

2”

The microphone echo cannot be adjusted

when not inserting microphone.

- 12 -

5 Delay When inserting microphone to sing Karaoke, you

may adjust microphone delay when the sound is not full.

Press the "DELAY" button on the remote

" "

control then press of to adjust the delay

" "

of microphone. The adjustable range is 0~7..

The microphone delay displays as "MIC DELAY 2”

The microphone delay cannot be adjusted when not inserting microphone.

7 Wide Field When inserting microphone to sing Karaoke, you

may select to switch on/off Karaoke wide field when the sound field is not wide.

Press the "WF" button on the remote control to display "MIC WIDE ON", which means Karaoke Wide Sound Field is switched on.

Press the "WF" button on the remote control again to display "MIC WIDE OFF", which means Karaoke Wide Sound Field is switched off.

The karaoke WF button cannot be selected when not inserting microphone. NOTE: If noise appears when adjusting Karaoke, please refer to TROUBLESHOOTING for details.

6 Modify When inserting microphone to sing Karaoke, you

may select microphone euphonize mode when the sound is unsuitable.

Pressing the "MODIFY" button on the remote

control can circularly select the euphonized

¡ï

voice"NATURAL", "Full", "Fruity", "Bright" and "Ringing".

The MODIFY button cannot be selected when

not inserting microphone.

2.2.11 Tuning Function

Auto Tuning One:

1 Press INPUT button on the front panel or remote control to select TUNER as the input sound source.

2 Press BAND button on the front panel or remote control to select receiving wave band.

7 Wide Field

When inserting microphone to sing Karaoke, you may select to switch on/off Karaoke wide field when the sound field is not wide.

- 13 -

3 Press TUNING / button on the front panel or remote control for above 5 seconds to automatically tune upwards/downwards until your needed radio station programs. When programs are searched, it will stop searching automatically.

3¡¢

NOTE: 1. This operation will search and save automatically, so the user-preset programs will be covered.

2. Pressing TUNING / button may stop the function in the course of this operation.

If the tuning searching stops in imperfect radio station (because of weak radio station signals or radio wave interferes), please change into manual tuning method.

Clear Radio Station

If you do not need the preset radio station, you may clear it by using CLEAR button on the remote control with the help of number buttons 0~9. 1 Press CLEAR button on the remote control. 2 Press the serial number of the radio station that you want to clear in the course of the screen's displaying”CLEAR " to finish this operation.

If the tuning searching stops in imperfect radio station or radio wave interferes, please continue operating.

If the tuning searching stops in imperfect radio station (because of weak radio station signals), please change into manual tuning method.

4 The following save and call operations are the same with manual tuning operations.

Auto Tuning Two:

1 Firstly select TUNER as the current input sound source according to the operations oF

"Manual Tuning", and then select the wave band to be received.

2 Press MEMORY button on the front panel or remote control, and then press TUNING / button for above 0.5 seconds during the course of displaying MEMORY to enter the radio station auto searching status.

NOTE: 1. This operation is beyond retrieve, so please take care to operate.

2. If you clear the radio station incautiously, you may save again according to the select operation.

The Explanation of MODE button

This unit has two working modes in the receiving status: AUTO/MANUAL

1 In AUTO working mode, if you select FM wave band, this unit will automatically recognize the radio station program is mono signal or stereo signal and keep the mono or stereo receiving status.

2 If the received radio station program has louder noise or cacophony in stereo status, you may switch to MANUAL working mode.In this way, the unit is in mono receiving status to decrease noise and cacophony generally. You may switch the two working modes through MODE button on the remote control.

- 14 -

Antenna Connection

You may use our accessional AM and FM indoor antenna when in bad receiving effect. Generally speaking, these antennae can supply enough signal strength.

Connect to AM Round Antenna

1 Push the jack button to open it.Push the jack button to open it.

2 Connect the AM round antenna cord to AM ANT and GND terminals.

3 Let go of the button to clamp the speaker cord. Pull the cord lightly to check the connection is right or not.

NOTE: 1. AM round antenna should be placed far away from the equipment. You may put up on the wall or on the bookshelf.

2. AM round antenna and outdoor antenna can be used at the same time.

Connect to FM Antenna

Connect to the indoor FM antenna Connect the accessional indoor FM antenna to

75 UNBAL.FM ANT terminal.

NOTE:Do not use the outdoor and indoor FM antennae at the same time.

How to Connect

Push the jack button to open it.

Insert the speaker cord.

Let go off the button to clamp thespeaker cord.

4 Connect the AM round antenna to the stand.

AM round antenna

5 Adjust the direction of AM round antenna to get the best receiving effect.

GND (Grounding) terminal

In order to ensure the safety and decrease the interference, please well connect the GND terminal. The better grounding method is insert the metal pole into wet ground.

2.2.12 Other Operations

1 Mute Mute the sound to make your conversation or answering telephone not be affected by music.

Press the MUTE button on the remote control to mute the sound and the display "MUTE" flickers.

Rotate

Mute

- 15 -

2 Child Lock To prevent the children wrongly pressing the front panel buttons, you may lock the buttons on

Other Operations

the front panel.

Press the CHILD LOCK button on the remote control to display "LOCK". The buttons on the front panel are invalid and now "LOCKED" displays.

Press the CHILD LOCK button on the remote control again to display"UNLOCK" and the fronta pnel buttons can be normally used.

The DISPLAY button cannot be selected when

no signals input.

3 Display To make the display spectrum colorful, we have set many kinds of spectrum display means. You may press the DISPLAY button to select.

After switching on the unit, it will automatically select a kind of spectrum display mode every third moment or so.

Pressing the DISPLAY button on the remote control can cancel auto switch and select your favorite display mode.

Pressing the DISPLAY button on the remote control repeatedly can select many kinds of spectrum display effects until auto switch.

4 Default When the system parameters adjusted disorderly, you may restore the default settings.

Press the DEFAULT button on the remote

control to display "DEFAULT".

The unit automatically sets the default

parameters.

Default

- 16 -

ChapterThreePrincipleandServicing

SectionOnePrincipleofthePlayer

AV225T(RU)isanadvancedpoweramplifierwithcompletefunctions.Basedontheformerpower amplifiers,itadoptsLCDscreen,withskybluebackgroundmatchedwith16differentkindsofspectrum displaystyles,inaddition,thisplayeriswithtuningfunctionanditisanexcellentselectionforuserswho lovelisteningtoradio.

3.1.1Compositionoftheplayer

1.Volumeboard:selectinputsignalsource,CyberLogicandbassenhancercontrol.

2.Signalprocessingboard:Karaokesignalprocessingand5.1CHsignalamplifying.

3.MCUboard:playercontrol,frequencypointgating,andautosearchcircuit.

4.Controlpanel:LCDdisplay,remotekeyboardandbackgroundlightdisplay.

5.Powerboard:supplytheworkingvoltagerequiredbyeachunitcircuitandperformplayer

protectionfunction.

6.Poweramplifierboard:performpoweramplifyingto5.1CHanalogsignal.

7.Digitaltuner:receiveradiosignalandthensendtopoweramplifierforsignalprocessing.

8.MIC,headphoneboard:MICsignalinput,headphoneamplifyingoutputcircuit.

9.Videoinputandoutputboard:fulfiltheswitchofVCD,DVDchannel.

3.1.2Functionandfeatures

Built-in5CHpoweramplifying,applicabletoAC-3/DTSandstereomusicreplay.Mainchannel

◆

80W,central/surround15Wwithstrongpower.

◆

AC-3/DTS,VCD,DVDinputjackandsubwooferoutputjack.

◆

6CHvolumecontrolandseparatelevelcontrol,with7-bandelectronicequalization.

◆

Bassenhancersystem,CyberlogicfunctionandHi-Fiplaybackfunction.

◆

Q-playfunctionofmovie,musicandKaraoke.

◆

MultipleEQmodes,applicabletodifferentmusicstyles.

◆

Autospectrumanalysiscompensationfunctionperformscompensationtosignalsautomatically.

◆

CompleteKaraokefunction,includingseparateMICvolumecontrol,high/lowtoneadjustment,

voicecompensation,delayandechoadjustment,Karaokewidesoundfieldfunction.

-17-

XS1

Powerboard

XS2

220V

XS3

Signaloutput

XL100

XS4

XS7

XS8

SWM RLY0

P_RC

OVER

R2 C2 SL2

SR2

VC+

GND

VC-

XP7

XP8

XP13

XP9

RLY P_RC

P_LRM P_CSM

SWM

L1 R1 C1

SL1 SR1

XS13

XS9

Videoboard

Volumeboard

XS20

XP20

Xp101

XS101

XP101

Tunersocket

XS22

XP22

SWITCH

Transformer elementary

Transformer

Sublevelcoil

XP23

+12V

GND

-12V

Controlpanel

DGND

+12V

GND

-12V

XP25

MICholder board

D+5V

XS25

CPUboard

XP12

XP100

XS6XS23

XS102

XP102

XS103

XP103

XS12

TUNER(L/R)

VCD(L/R)

DVD(L/R)

5.1CH(L/R)

Volume board

5.1CH(C/SL/SR)

5.1CH(SW)

Input selection

DLSPLY

A B

L/R

Follow buffering

L/R

5.1CH(C/SL/SR)

5.1CH(SW)

S-C C/SL/SR/SW

MIC

Mix

Cyber logic

S-C/S-SL/S-SR

S-C

D-SW

A B

5.1CH LR_T

Channel selection

LR_T

5.1CH

C/SL/SR

Mix

Electronic volume

L/R

SL/SR

L/R/C

Headphone amplifier

MIC

MIC, headphone board

MIC input

Signal board

VCD

2 3

DVD

4 5

V-OUT

Video in/out board

C/SL/SR

Power amplifier board

CD4051

Mute

Power amplifying

Load

test

AGND

+12V

-12V

Preposition power

VS+ GND VS-

Power

SW-OUT

volume

tone

Amplifying

amplifying

Program

Amplifying

+6.8V

AGND

-6.8V

Switch in bass enhancer and line output

filtering

compare

Bandpass

Dual-limit

boost

Low frequency

Detect

switch

channel

Detect

EEPROM

24C02

echo

Electronic

Echo

adjustment

Delay

adjustment

Sampling

intermit

P_SELECT P_SEARCH

Reset

circuit

CPU board

Reverse

VSTNDANCK

P_CHARGE

CPU

DIST

MIC direct connection

P_DO-P_D7

RST/RS/RW/PE

P REM

PT2222 remote control buttons array

DVD all-in-one input

amplifying

Preposition

MIC

+12V

AGND

3.1.4 The player signal flow chart

The player signal flow chart is shown as the following figure 3.1.4.1:

-12V

Power

±6.8V

Mixed

L/R

Mixed

Clipping

OK-R

Mixed

Clipping

OK-L

LCD display

OKL/OKR

SR/SL

+12V

Power

AGND

±6.8V

-12V

-VS

Remote control receiving

Mixed Mixed Mixed

+6.8V

AGND

-6.8V

+5V

Control panel

Protection circuit

Relay

drive

Relay

SW mute and relay state detect

VC+

AGND

VC-

Main power amplifier power

Power board

R C SL

- 19 -

Figure 3.1.4.1 The player signal flow chart

Section Two Unit Circuit Principle

3.2.1 Volume board circuit

AV225T (RU) has 4 kinds of input means in all: tuning input, VCD, DVD stereo input and 5.1CH

input. The Cyber logic function of AV225T (RU) is to achieve C, SR, SL and SW signal through buffer and

processing of adder and subtracter after sampling from L, R channels. In this circuit, electronic

simulation switch is adopted to fulfil the switch in all kinds of state. Signal flow is shown as the following

figure 3.2.1.1:

Tuner

VCD

DVD

1CH

N101

CD4052

Electronic switch

N10

N105B

N10

S SR

S SL

S-C

N104A

4053

Electronic switch

N102

4053

Electronic switch

N103

N104B

N106

OUT

M62446

SWIN

N107A

N108B

DISPLY

Figure 3.2.1.1 Volume board signal flow chart

- 20 -

1. Input selection and sound field processing mode

A X B Y C Z

0 X0 0 Y0 0 20

1 X1 1 Y1 1 Z1

Mode Pin

Tuner VCD DVD 5.1

A 0 1 0 1

B 0 0 1 1

The input selection of AV225T (RU) is fulfilled through electronic switch CD4052 and CD4053, and

the truth value table is shown as follows:

CD4052 Truth value table

CD4053 truth value table

(1) 5.1CH input state: now A, B, 5.1CH of M62446 are in high level, L and R channel signals of

5.1CH input terminal are outputted from pin 3, 13 of N101 respectively and then sent to IC N106 for

volume and tone adjustment; meanwhile C, SR, SL signals of 5.1CH input terminal are outputted from

pin 14, 15, 4 of N102 and then sent to IC N106 for separate volume adjustment; in addition, SW signal of

5.1CH is outputted through pin 4 of N103, amplified by N107A and then sent to M62446.

(2) 3 kinds of analog input modes: AV225T (RU) has 3 kinds of analog input modes: tuning signal,

VCD and DVD are controlled through signals A, B separately. Please refer to CD53 truth value table for

reference.

(3) AV225T (RU) has 3 kinds of sound field modes in all: standard, Cyber logic and Hi-Fi.

A. Standard: under the control of the player MCU, when bass enhancer is off, left channel, right

channel and subwoofer have output; when bass enhancer is on, only left and right channels have output.

B. Hi-Fi: under the control of MCU, only left and right channels of M62446 have output; when bass

enhancer is off, volume adjustment is off.

C. Cyber logic: pin 9, 10 of electronic switch N101 (CD4052) select a group of analog left and right

channel input signals according to the truth value table, the left and right channel signals are outputted

from pin 3, 13 through the electronic switch inside N101 and divided into 2 ways: one way is sent to pin

13, 15 of M62446 for electronic volume and tone adjustment, and the other way gets SW, S-SR, S-SL

and S-C signals though buffer and adder and subtracter, in which S-C, S-SR and S-SL signals are sent

to pin 12, 2, 5 of N102, under the control of 5.1CH signal, N102 selects Cyber logic signal input (see

Cd4053 truth value table) from Cyber logic and 5.1CH signal, central, right surround and left surround

signals are outputted from pin 14, 15 and 4 respectively and then sent to pin 11, 8 and 9 of M62446 for

volume adjustment. Another SW signal is outputted from N107A and then sent to pin 6 of M62446.

5.1CH signal sen t to M62446 outputs from pin 31, 36 after volume adjustment, and then is outputted by

XS20 flat cable holder to signal board.

(4) The relationship between the switch in all kinds of sound sources and sound handling mode in

input circuit is show as the following figure 3.2.1.2:

- 21 -

Only L/R channel has output, sound field and EQ setup is invalid

Only L, R and SW channel has output, capable of performing sound field and EQ setup

6CH output, capable of performing cinema sound field and EQ setup

Press INPUT button to select circularly

Hi-Fi mode

2 kinds of analog input modes

5.1CH input mode

Figure 3.2.1.2 Illustration between input circuit

Standard mode

Cyber logic mode

6CH output, capable of performing cinema sound field and EQ setup

2. Control circuit

The latched, data and clock signals outputted by MCU (N100) pin are sent to pin 39, 40, 41 of

M62446, pin 1, 2, 3, 4 of M62446 output control level to select the input signal and spectrum sampling

signal. Other functions, such as volume and tone adjustment, are also controlled by the three control

signals. The display of display screen is controlled by CPU directly.

3. Spectrum sampling circuit

The spectrum sampling in AV225T (RU) is sent from pin 13 of N103 to N108B for amplification, and

then sent to spectrum gating circuit. 5.1CH of M62446 selects sampling signal. When selecting Cyber

Logic, 5.1CH control signal is low level, now pin 9, 11 of N103 is low level, and it is known from the truth

value table that the output is X0 and Z0 and this two sampling signals are grounded. It is known from

Cyber logic principle, centre, surround and subwoofer channels are all produced by left and right

channel signals, but in S-C signal, complete left and right channel signals are included, so it is ok to

sample from S-C only. Therefore, S-C signal is outputted through R195 (pin 13 of N103) to N108B and

added with OK-R signal for the amplification of spectrum sampling signal, and then sent through XS20

to frequency point gating and auto search circuit; the same, when selecting 5.1CH input, 5.1CH control

signal is high level, pin 14, 15, 4 of N102 select pin 14, 4 of X1, Y1, Z1 of N103 and connect to X1, Z1,

thus, the 6-channel signals are outputted through pin 13 of N103 to N108B and added with OK-R signal

for the amplification of spectrum sampling signal, and then sent to frequency point gating and auto

search circuit through XS20.

4. Tuning function

This player has tuning function, which provides a good selection for users. It directly controls digital

tuner through MCU to receive audio signal, and then output after amplification by power amplifier. The

clock and data line of digital tuner is commonly used together with M62446, the other two control lines

are directly connected to MCU, L, R signals after being handled by digital tuner are directly sent to pin 1

and 12 of N101 CD4052 for gating input.

- 22 -

3.2.2 Signal processing board circuit

IC SN IC name IC function IC SN IC name IC function

N201 4558

Operational amplifier performs preamplification to voice signals

N207 CD4051 Karaoke delay adjustment

N200 PT2315

Karaoke volume adjustment, including tone adjustment

N208 CD4051 Karaoke echo adjustment

N205 CD4053 Electric switch N204 4558 Inverter

N209 PT2399 Karaoke echo settlement

The signal board performs mixed amplification to 5.1CH signal sent from volume board, voice signal

sent from microphone, headphone board and Karaoke echo signal.

1. AV225T (RU) Karaoke circuit

(1) Function: this circuit is to reset by loudspeaker after handling voice and being amplified by

power amplifier. It includes voice beautification circuit, wide sound field processing circuit and Karaoke’s

echo and delay adjustment circuit.

(2) Function of IC of Karaoke circuit is shown as the following table:

(3) Karaoke signal flow chart

MIC

N20A1

N202A

V200

N200

P_OKT

N202B N203B

N100

Figure 3.2.2.1 Karaoke signal flow chart

N211 N100

N209

N207

N208

N204

Directly connected

N205

Mixed output

Shown as in the figure 3.2.2.1, when microphone is inserted, MIC signal is sent to N201A

operational amplifying circuit for amplification. One path of MIC signal after being amplified gives MCU a

microphone input identification signal P_OKT through VD201 rectification filtering control triode V200

after being amplified by N202A; when there is signal input, P_OKT is low level, MCU makes N210

CD4094 send out KM low level signal to make triode V103, V105, V104 ccutoff and then to make MIC

signal can output; the other path is coupled by C219 to pin 6 of PT2315, and then output from pin 16

after internal volume adjustment to N202B and N203B for amplification. The signal after being amplified

of N203B is divided into two paths, one path outputs directly, and the other path is coupled byR222,

C247 to PT2399 inside for delay and echo adjustment and then outputs from pin 14, and then mix output

- 23 -

Together with direct connection OK signal through N204B, while OK-R is outputted from pin 14 after

being gated by N205 and then overlapped to left and right channels.

In this circuit, the low frequency exalt network composed by triode V201 connected to the reverse

end of N202B is mainly to exalt 75HZ low frequency signal.

When performing delay adjustment to PT2399, firstly give control signal to MCU, and MCU controls

N207 after being extended by N211 IC CD4094, then selects different resistance value to connect into

pin 6 of PT2399 to reach the purpose of delay adjustment.

Similarly, through changing the resistance value in R229 to change the echo level overlapped to

direct connection signal, the echo adjustment is realized.

The wide sound field control signal of Karaoke is sent by N211 to pin 11 of N205, when it is high

level, pin 14 of N205 is connected to X1, now the phase of OK-R signal is reverse from that of OK-L,

sound field is widened and Karaoke is in wide sound filed state. On the contrary, the phase of OK-R

signal is the same with that of OK-L, Karaoke is in the narrow sound field state.

In addition, microphone plug has a detect signal P_MICDET, and it composes the detection to

microphone inserting together with the circuit composed of V202. When microphone is not inserted, it is

low level, V202 cutoff; when microphone is inserted, it is high level, V202 is on, now turn off scene

surround mode and forbid tuning.

Otherwise, there is OK auto mute function. When P-KT cannot detect any signal in a continuous

period, MCU will send out a control signal to make KM be high level, triode V103, V105, V104 is on to

mute OK signal to advance SNR of the player and better listening effect.

(4) Scene mode signal flow

AV225T (RU) has a special function, that is, it may realize switch in 5 kinds of scene mode when there

is no Karaoke, which is fulfilled by Karaoke part. Signal flow chart is shown as in the figure 3.2.2.2:

R- 1

L -1 C- 1

N205

Mixed output

N203B

N209

N207

N208

N204B

Figure 3.2.2.2 Scene mode signal flow chart

When pin 9 and 10 of N205 is in high level, the sampled L, R, C signals are outputted by pin 3

through N205 gating, after being amplified by N203B, one path is sent to PT2399 inside for echo and

delay adjustment (controlled by IC CD4094), the effect after adjustment is overlapped to L, R, C channel

- 24 -

To form various scene modes. Seen from this, its principle is the same with that of Karaoke. In scene

mode, it functions only when microphone is not inserted and in 5.1CH mode at the same time.

2. Bass enhancer circuit

BURST sent out by N210 is bass enhancer on/off signal. When it is high level, it is added to base

electrode of V102, V102 is on, base electrode outputs low level, V107, V100 are cutoff, SW signal

outputs to external terminal normally, at the same time, BURST high level signal is added to emitting

electrode of V108, V108 is on, collector electrode output high level is added to the base electrode of

V101, V101 is on to make SW signal grounding and it will not be overlapped to left and right channel

signals.

Reversely, when BURST is low level, V100 is on, SWM signal cannot output from external terminal,

at the same time V101 is cutoff, SW signal is overlapped to left and right channel signal.

Bass enhancer of AV225T (RU) is divided into 3 levels, the principle is to change the high/low of

bass enhancer level through changing SW output volume of M62446.

Meanwhile, SWM signal is added to relay through XS9, when relay is disconnected, SWM signal is

grounded to make subwoofer terminal have no output to avoid the concussion to speakers at the

moment of power-on.

3. 5.1 signal and Karaoke signal mixed amplification circuit

Left and right channel signals of 5.1 signal, after being mixed with SW signal and being amplified by

N101B, N100B, are sent to the reverse end of N101A, N100A, at the same time, OK-R, OK-L signals are

respectively added to the reverse end of N101A, N100A and then output from pin 1 of N100A, N101A to

power amplifying circuit for amplification after the mixed amplification of N100A, N101A.

Meanwhile, the centre C-1 signal sent from volume board is added to the pin 6 reverse end of

N102B, and then added to the reverse end of N102A after amplification. Now the C1-1 signal after

processed by echo (scene surround mode) is also required to add to the reverse end of N102A and

mixed amplifying with it, then sent to centre channel power amplification circuit.

Surround SR-1, SL-1 signal of the other path volume board is directly sent to surround channel

power amplification circuit.

One path of 5.1 signal after mixed amplification is sent to power amplification circuit through XS9,

the other path forms DIST signal (distortion detect signal) to MCU board through R111, R112, R142,

R145, VD100-VD104 to perform auto gain adjustment to control the volume output.

3.2.3 MCU board circuit

MCU board is composed of player control circuit, auto search input signal and spectrum analysis

circuit.

- 25 -

1. The player MCU control

N100 is the control centre of the player, various control instruction are outputted by it to each

controlled circuit to fulfil each control function. +5V power supply is adopted, and pin 40 is its power

supply pin. Pin 18, 19 externally connects with 12M crystal oscillator to provide itself with working clock

frequency. Pin 9 is its reset pin, when power on, +5V charges C106 through R100. The voltage on the

two ends of capacitor cannot change suddenly, so B-pole of triode V100 is low level, that is, V100 is not

on, a high level reset signal is given to MCU. When capacitor C106 charging finishes, V100 is on, now

reset finishes. Form of this kind of reset circuit is high level reset, and low level is kept.

When the player is working, information of power-on picture and Chinese characters when

operating displayed on display screen are all saved in the static memorizer inside MCU. N101 is a state

memorizer and it can save the working state of the player at the time of power-off and then call these

states until power-on next time to avoid the adjustment of users again. All kinds of user-set sound field

modes are also saved in it and can be called when necessary.

2. Input signal detecting, search circuit automatically

DISPLAY signal from volume board is sent to N103A for amplification, after being coupled by

capacitor C110, sent to the reverse end of voltage comparator N103B, outputted from pin 7 of N103B,

then sent to pin 16 of the player MCU through VD103, V101, R109, R107. When N103B outputs a high

level, Vd103 is in reverse cutoff state, B-electrode of switch pipe V101 is high level, now switch pipe

V101 is in on state, and then a +5V P_SEARCH high level is achieved through VD101 voltage regulating

to MCU, which means there is no signal input, and the search continues. When output terminal of N103B

outputs a low level, VD103 is in positive direction on state, B-electrode of switch pipe V101 is low level,

now switch pipe is in curoff state, MCU detects that P_SEARCH is low level, which means there is signal

input, at the same time, the search stops. The working principle is as follows:

(1) After power-on, under the control of MCU internal program, data signal is outputted to M62446,

then M62446 sends out high/low level to perform scanning to N101, N102, N103 each input port of

volume board, at the same time, P_SELECT is high level, V102 is on, now the in-phase end voltage of

comparator N103B is about 0.1V. When these input ports have no signal output, voltage of pin 6 of

N103B is less than 0.1V, pin 7 outputs 12V, Vd103 is in reverse cutoff state. It is known from the above

analysis, P_SEARCH is high level, which means there is no signal input. After all ports being searched

once, it enters standby state automatically; when a certain port has signal input, this signal is compared

with pin 5 of N103B through N108B of volume board and MCU board N103A amplification, if voltage of

pin 6 of N103B is more than 0.1V, pin 7 outputs -12V, Vd103 is in positive direction on state, now,

P_SEARCH is low level, which means there is signal input, through controlling IC M62446, MCU locks

this port that has signal input to enter normal playback.

(2) When pressing “GOTO” button on remote controller, through remote control receiver on the

panel, the switch from light signal to electric signal is performed, thus, pin 11 of MCU sends out a high

- 26 -

+ 96 hidden pages

BBK AV225T Service Manual

Specifications and Main Features

Frequently Asked Questions

User Manual