BBK SP550S User manual

ENGLISH
SP550S
Service manual

CAUTIONS
SP550S SERVICE MANUAL
There is high voltage inside this unit. Make sure to pull out the plug of this unit before
repairing!
There are many high voltage components inside this unit. Please pay attention to all
warnings and instructions marked on this unit to avoid electric shock!
Specifications of the replaced components must be the same as that of the original
components. Do not change the components' specifications to prevent risks!
Contents
1 SP550S FEATURES
2 CIRCUIT CONNECTION DIAGRAM & BLOCK DIAGRAM
3 DETAILED CIRCUIT EXPLANATIONS
10 THE EXPLANATION FOR KEY COMPONENTS
VOLUME CONTROL IC PT2258
CPU IC AT89C2051
POWER IC TDA7370B
POWER IC TDA2003
POWER IC LM1875
CAUTIONS
CONTENTS

5.1CH volume and level adjustment incorporate IC PT2258 and realize the standby and mute
functions.
CPU incorporates IC AT89C2051.
Small signal amplification and amplified LPF incorporate IC NJM4558.
Power amplification of L, R, SL and SR channels incorporates power IC TDA7370B.
Power amplification of the C channel employs power IC TDA2003.
Power amplification of the SW channel employs two LM1875 to form BTL.
Status display employs a LED digital tube, displayed range: 0~16.
Full function remote control.
Square power transformer, bridge and full wave rectifying circuit.
Satellite speakers employ plastic body. Subwoofer speaker's body employs xyloid MDF
construction with PVC cover.
Satellite speakers employ 3-foot wide frequency band high performance unit.
Subwoofer incorporates 8-foot aluminum audio coil with dual magnetic circuits exclusively for
the subwoofer unit.
All-in-one flat radiator board with long radiator sluts for excellent heat radiation.
1
SP550S SERVICE MANUAL
SP550S FEATURES

CIRCUIT CONNECTION DIAGRAM & BLOCK DIAGRAM
2
BLOCK DIAGRAM
5.1CH
L R SL SR
SW
L
R
C
SL
SR
LED
LPF
LL
R
C
SW
SL
SR
LLRSL SR
C
SW
C
SW
CPU
LR
INPUT BOARD
MAIN POWER AMPLIFYING BOARD
VOLUME
CONTROL
INPUT
BUFFER
AMPLIFICATION
POWER
AMPLIFICATION
POWER
AMPLIFICATION
POWER
AMPLIFICATION
AMPLIFICATION
OUTPUT BOARD
REMOTE
CONTROL
RECEPTION
DISPLAY
POWER
SUPPLY
FRONT PANEL'S CONTROL BOARD
SP550S SERVICE MANUAL
OUTPUT BOARD
~14V
0
~14V
Vs RM b1+c1 b2 a2
XP3
XS3
XS2
Vs RM b1+c1 b2 a2
1.
1.1.
2.
2.2.3.3.
3.
4.4.
5.5.
Transformer
c2c26.6.d2 e2 f2 GND g2
XS4 XP4
d2 e2 f2 GND g2
7.7.8.8.9.9.10.10.
11.11.
SL
R
L
SL
R
L
GND
GND
C
SR
GND
GND
C
SR
1.1.
1. 1.
2.2.
2. 2.
3.
3.3.
4. 4.
3.
GND
L
R
GND
L
R
SW
SR
SL
C
SW
SR
SL
C
1.1.
1. 1.
2.2.
2. 2.
3.
3.3.
4. 4.
3.
XS1
XP2
-
+
SW SPEAKER
SW
INPUT BOARD
POWER AMPLIFYING BOARD
FRONT PANEL'S BOARD
CIRCUIT CONNECTION
DIAGRAM

3
DETAILED CIRCUIT EXPLANATIONS
1. THE POWERAMPLIFYING BOARD
MAIN PARTS LIST OF THE MAIN POWERAMPLIFYING BOARD
NO LOCATION SP ECIFICATI ONS DESCRIP TIO N SPECIFICATIONS / PA RT NUMBER
1R405 Carbon-filmResistor 1/6W680¦¸ ±5% SHAPED 7.5
2R406~R412,R451,R455,R470 Carbon-film Resistor 1/6W1.5K±5% SHAPED 7.5
3R415,R419,R421,R424,R425,R428 Carbon-film Resistor 1/6W4.7K±5% SHAPED 7.5
4R404,R434,R437,R440,R443,R466 Carbon-film Resistor 1/6W10K±5% SHAPED 7.5
5R435,R438 Carbon-film Resistor 1/6W12K±5% SHAPED 7.5
6
R450,R458,R452,R454,R456,R416,R418,
R422,R423,
R426,R427,R441,R444,R459,R465
Carbon-filmResistor 1/6W22K±5% SHAPED 7.5
7R446,R467 Carbon-film Resistor 1/6W47K±5% SHAPED 7.5
8R432,R433,R439,R442,R447,R448,R464,
R445,R436 Carbon-film Resistor 1/6W100K±5% SHAPED 7.5
9R417,R420,R429~R431 Carbon-film Resistor 1/6W150K±5% SHAPED 7.5
10 R413,R414,R453,R457,R463 Carbon-film Resistor 1/4W10¦¸ ±5% SHAPED 10
11 R462 Carbon-filmResistor 1/6W2.2¦¸ ±5% SHAPED 7.5
12 R401,R402 Carbon-film Resistor 1/2W220¦¸ ±5% SHAPED 12.5
13 R449 Carbon-filmResistor 1/6W220¦¸ ±5% SHAPED 7.5
15 R460 Carbon-filmResistor 1/6W47¦¸ ±5% SHAPED 7.5
16 R403 Carbon-filmResistor 1/4W180¦¸ ±5% SHAPED 10
17 R461 Carbon-filmResistor 1W220¦¸ ±5£¥
18 C459 Porc el ain Capaci tor 50V 33P±10% NPO2.5mm
19 C462,C428,C430,C460,C461 Porc el ain Capaci tor 50V 151 ±10% 2.5mm
20 C417,C418 Porc el ain Capaci tor 50V 20P±10% NPO2.5mm
21 C405,C406,C409,C410,C413,C416,C456,
C458 Porc el ain Capaci tor 50V 104 ±10% 5mm
22 C424,C436 Terylene Capacitor 100V 103 ±10% 3.5mm
23 C440,C442,C445 Terylene Capacitor 100V 104 ±10% 7mm
24 C401,C402 Terylene Capacitor 100V 224 ±10% 8mm
25 C425,C437 Terylene Capacitor 100V 182 ±5% 3.5mm
26 C447~C450 Metal Polyester Film
Capacitor CL21X 100V224±10% 7.5
27 C415,C432,C457 CD CD11 16V10U±20%5×11 2
28 C414,C451 CD CD11 16V47U±20%5×11 2
29 C412 CD CD11 16V220U±20%6×12 2.5
30 C407,C408,C444 CD CD11 16V470U±20%8×123.5
31 C439,C441 CD CD11 25V22U±20%5×11 2
32 C419~C423,C426,C427,C429,C431,C433,
C434,C435,C438,C443 CD CD11 50V2.2U±20%5×11 2
33 C403,C404,C411 CD CD11 25V4700U±20%16×35 7.5
34 C446,C452~C455 CD CD11 25V220U±20%8×12 3.5
35 VD412,VD413 Diode 1N4004
36 VD401~VD406 Diode RL254
37 VD41 1 Voltag e Re gul ator Di ode 5.1V1/2W
38 VD409,VD410 Voltag e Re gul ator Di ode 12V 1/2W
39 N402 Software ProgramCPU,
AT89C2051 DIP CPUHT60(EN)-0
40 N404~N406 IC 4558C DIP
SP550S SERVICE MANUAL

4
43 N403 IC PT2258 DIP
44 N410 IC TDA7370B MULTIWATT15V
45 N409 IC TDA20 03 PENTAWATT
46 G401 Crystal Oscillator 4.0MHz 49-U
47 PCB 4MA800-1
48 XS2 ,XS 5 Socket 7 PINS 2.5mm
49 XS1 Socket 3 PINS 3.96mm
50 XS3 Socket 12 PINS 2.5mm
51 W1,W3~W8,W11,W14,W17,W18,W20,
W23,W28,W27,W19,W24 Connection Cords ¦µ
0.6 SHAPED 7.5mm
52 W9,W10,W13,W21,W22,W25,W26 Connecti on Cords ¦µ 0.6 SHAPED 10mm
53 W2,W12,W15 Connection Cords ¦µ 0.6 SHAPED 12.5mm
54 W16 Connection Cords ¦µ 0.6 SHAPED 15mm
55 XP7 Raft Cords 4P300 3.96 1 PLUG
56 XP6 Raft Cords 2P90 2.5 1 PLUGWITHNEEDLES,
BLACK 22 # CORDS
57 FL401,FL402 Fuse Tube T4AL 250V
58 FL401,FL402 Fuse Holder 0
DETAILED CIRCUIT EXPLANATIONS
SP550S SERVICE MANUAL

5
DETAILED CIRCUIT EXPLANATIONS
SP550S SERVICE MANUAL
SCHEMATIC DIAGRAM OF THE MAIN POWERAMPLIFYING BOARD
Vin
1
GND
2
Vout 3
N401 7809
VD401~VD404
RL254
C438 2.2u/16V
R450 22k
A+18V
A-18V
R452
22k
R451 1.5k
C439
22u/25V
C440 104
R453 10
C414 47u/16V
R454
22k
A+18V
A-18V
R456 22k
R455 1.5k
C441 22u/25V
C442 104
R457 10
R458 22k
R403
180
1 2
53
4
-
+
N408 LM1875
1 2
53
4
-
+
N407
LM1875
1 2
53
4
-
+
N409
TDA2003
C444 470u/25V
R460 47
R461
220
R462
2.2
C459
33p
C446
220u/25V
C434 2.2u/16V
C456 104
R463
10 C445
104
OUT1 1 OUT2 2 OUT3 15 OUT4 14
IN1
4
IN2
5
IN3
12
IN4
11
SVR
6
PG
8
SG
9
C.D
10
S-B7
Vcc13
Vcc3
N410
TDA7370B
C451 47u/16V
C455
220u/25V
C454
220u/25V
C453
220u/25V
C452
220u/25V
FL402
T4AL250V
FL401
T4AL250V
1 2 3
XS1 3PIN
C403
4700u/25V
C404
4700u/25V
C411
4700u/25V
A+18V B+18V
A-18V
B+18V
A+18V
C458 104
C405 104
C406
104
C412
220u/16V
C407
470u/16V
C408
470u/16V
C413 104 VD411
5.1V
+5V+9V
VD410
12V
VD409
12V
R401
220/0.5W
R402
220/0.5W
+12V
-12V
C401 224 C402 224
R415
4.7k
R416
22k
R422
22k
R424
4.7k
R425
4.7k
R426
22k
C417 20p
C418
20p
C415 10u/16V
C432
10u/16V
C426 2.2/16V
C431 2.2u/16V
1 2 3 4 5 6 7
XS5
7PIN
IN1
1
IN2
2
IN3
3
CODE2
4
DGND
5
SCL
6
SDA
7
IN4
8
IN5
9
IN6
10
OUT1 20
OUT2 19
OUT3 18
CODE1 17
Vcc 16
REF 15
GND 14
OUT4 13 OUT5 12 OUT6 11
N403
PT2258D
REMOTE
G401
4M
1 2 3 4 5 6 7 8 9 10 11 12
XS3
11PIN
R406 1.5k R405 680
R407 1.5k
R408 1.5k
R4091.5k
R410 1.5k R411 1.5k
R412 1.5k
Vs
C416
104
R404 10k
R464 100k
C457
10u/16V
C449 224 C447 224
C448 224 C450 224
+9V
R459
22k
R421
4.7k
R419
4.7k
R418
22k
R423
22k
R428 4.7k
R427
22k
R429 150k
R417
150k R420 150k
C420
2.2u/16V C419
2.2u/16V
C421
2.2u/16V C422
2.2u/16V
C423
2.2u/16V
R435
12k
R438
12k
R437
10k
3 2
1
84
N404A 4558
5 6
7
N404B 4558
C437
182
C425 182
C424 103
+12V -12V
R448
100k
R444
22k
R430 150k
R447
100k
R434
10k
C436 103
R436
100k
R446
47k
C435 2.2u/16V
3 2
1
84
N405A 4558
5 6
7
N405B
4558
3 2
1
84
N406A
4558
5 6
7
N406B
4558
-12V
-12V +12V
R443 10k
R440 10k
C427
2.2u/16V
C429 2.2u/16V
+12V
R439
100k
R433 100k
R445 100k
R442
100k
R449 220
C433 2.2u/16V
+5V
RESET
R465
22k
R432
100k
R441
22k
R431
150k
C443
2.2u/16V
R413 10
R414
10
C409
104
C410 104
Vs g1 REMOTE b1+c1 a2 b2 c2 d2 e2 f2 g2 GND
L
R
SL
SR
SR SL L R C GNDGND
VD405
RL254
VD406 RL254
C430 151
C428
151
C461
151
C460
151
RST/Vpp
1
P3.0
2
P3.1
3
XTAL2
4
XTAL1
5
P3.2
6
P3.3
7
P3.4
8
P3.5
9
GND
10
Vcc 20
P1.7 19
P1.6 18
P1.5 17
P1.4 16
P1.3 15
P1.2 14
P1.1 13
P1.0 12
P3.7 11
N402 AT89C2051
R466
10k
+5V
R467
47k
C462
151
Vs
Vs
R470
1.5k
VD412 1N4004 VD413 1N4004
From Trans.
To Display Board
1 2 3 4 5 6 7
XS2 7PIN
GG L R C SL SR SW
1 2 3 4
XP7
4PIN
Vs GND
From Input Board
To Sub-AMP Board
To Sub-AMP Board

6
NOTE:
When repairing the power amplifying board, make sure that the IC is fixed to the big radiator board closely
and rightly without any inclination in assembling the Power IC N407, N408, N409 and N410. A silicon oiled
mica spacer needs to be placed between the IC and the big radiator board. When fixing the screws of the
Power IC N407, N408, N409 and N410, the insulating spacers need to be placed between the screws and
the Power IC. A multimeter can be used to detect whether the insulation is effective or not. Otherwise, a
short circuit may be resulted to burn out the Ics.
DETAILED CIRCUIT EXPLANATIONS
NO. LOCATION SPECIFICAT IONS DESCRIPT ION SPECIFICATIONS / PA RT NUMBER
1R306 Carbon-film Resistor 1/4W4.7K±5% SHAPED 10
2R307 Carbon-film Resistor 1/6W56K±5% SHAPED 7.5
3R308 Metal FilmResistor 3W20¦¸ ±5% R-SHAPED 20 x 8
4R301~R305 Carbon-film Resistor 1W100¦¸ ±5% R-SHAPED 15 x 8
5C301 CD CD11 25V 330U±20% 8 x 14 3.5
6C302 CD CD11 25V 47U±20% 5 x 11 2
7VD301,VD303,VD304,VD305 Diode IN4148
8VD30 2 Voltag e Re gul ator Di ode 6.8V1/2W
9V301 Tri ode 9014C
10 V302,V303 Tri ode S8050D
11 Y301~Y303 Rel ay JH4237-012-2HDC12V
12 XP5 Raft Cords 7P 180 2.5 2 PLUGS WITHNEEDLES
13 XS4 Socket 7 PINS 2.5 mm
14 XS8 Socket 2 PINS 7.92mm
15 XS7 Socket 4 PINS 3.96mm
16 PCB 3MA 800-1
17 W1,W2 Connection Cords ¦µ 0.6 SHAPED 7.5 mm
SP550S SERVICE MANUAL
MAIN PARTS LIST OF THE AUXILIARY POWER AMPLIFYING BOARD
SCHEMATIC DIAGRAM OF THE AUXILIARY POWER AMPLIFYING BOARD
V302
S8050
VD303
1N4148
C301
330u/25V R308
20/2W
Y301
V301
9014
VD304
1N4148
Y302
VD305
1N4148
Y303
GSADC12V
C302
47u/25V
VD302
6.8V
R307
56k
1
2
3
4
5
6
7
XS4
7PIN
R306
4.7k VD301
1N4148
SL
R
L
SR
C
GND
1
2
XP6
2PIN
GND
R301
100 R305 100
R304
100
R303
100
R302
100
XJ4
XJ6
1
2
3
4
5
6
7
XP5
7PIN
GND
C
SR
L
R
SL
1
2
3
4
XS7
4PIN
1
2
3
XS8
3PIN
V303
S8050
Vs
GND
From Sub-AMP Board
From Sub-AMP Board
To Output Board
To SW Speaker
GSADC12V
GSADC12V

7
DETAILED CIRCUIT EXPLANATIONS
2. INPUT BOARD
MAIN PARTS LIST OF THE INPUT BOARD
NO. LOCATION SPECIFICAT IONS DESCRIPT ION SPECIFICATIONS / PA RT NUMBER
1PCB 1BSY02-1
2XC1 Terminal Socket AV6-8.4 - 3C
3XP2 Raft Cords 7P130 2.5T2 6 SHIELDED WITHNEEDLES,
PIN7 GROUNDED
MAIN PARTS LIS T OF THE INPUT BOARD
SP550S SERVICE MANUAL
SCHEMATIC DIAGRAM OF THE INPUT BOARD
C
R
SR
L
SW
SL
1
2
3
4
5
6
7
XP2
7PIN
Signal Source To Power AMP Board

DETAILED CIRCUIT EXPLANATIONS
3. FRONT PANEL'S CONTROL BOARD
MAIN PARTS LIST OF THE FRONT PANEL'S CONTROL BOARD
NO. LOCATION SPECIFICAT IONS DESCRIPT ION SPECIFICATIONS / PA RT NUMBER
1C901 Porc el ain Capaci tor 50V 104 ±20% 5mm
C901 Stone Capaci tor 50V 104 ±20% 5mm
C901 Chip Capaci tor 50V 104 ±20% 0805
2DS901 LED Digital Tube E20361-G
3PCB 9BSY02-3
4XP3 Raft Cords 12P300 2.5 1 PLUG
5N901 InfraredReceptor HS0038B
6Affix N90 1 Soft S ponge P ad 10×10×1 DOUBLEHARD SIDED
MAIN PARTS LIS T OF THE FRONT PANEL'S CONTROL B OARD
8
SP550S SERVICE MANUAL
SCHEMATIC DIAGRAM OF THE FRONT PANEL'S CONTROL BOARD
1
32
N901
HS0038B
REMOTE
Vs
+5V+5V
1 2 3 4 5 6 7 8 9
10
11
12
XP3 12PIN
C901
104
b1
c1
a2 b2
c2
d2 e2
f2
g2
1431110875129
6
g1
13
J?
LED4
COMMON ANODE

DETAILED CIRCUIT EXPLANATIONS
4. POWER SWITCHBOARD
MAIN PARTS LIST OF THE POWER SWITCHAND POWER ICOF THE AMP BOARD
SW 6A/250V
C
0.01u/400V ~14V
~14V
FL
T1.6AL250V
L
N
E
~220V
50Hz
TRANS
TK6301500
1
2
3
XP1
3PIN3.96
To AMP Board
NO. DESCRIPTION SPECIFICATIONS/PART NUMBER LOCATION SPECIFICATIONS
1Porcelain Capacitor CT7 400V 103 ±20% 10mm PO WER S WITC H
2Power S witch PS8-11 2#
3Mains Cords 2P1.9m10A STC-999(MX)
4Fuse Tube T1.6AL250V FUS E TU BE H O LD ER
5Mica S pacer 24×22×0.1 N410
Mica S pacer 22×20×0.1 N410
6Insulation Cannular ¦µ 3×6×3 N407~N410
7Pyrocondensation
Cannular ¦µ
25 PO WER S WITC H
8Mica S pacer 18×13×0.1 N407,N408,N409
MAIN P ARTS LIS T O F THE PO WER SWIT CH AN D PO WER IC O F THE AMP BO ARD
9
SP550S SERVICE MANUAL
SCHEMATIC DIAGRAM OF THE POWER SWITCH BOARD

10
THE EXPLANATION FOR KEY COMPONENTS
1N1
OUT1
OUT2
OUT3
OUT4
OUT5
OUT6
VCC
REF
1N2
10dB/Step
10dB/Step
1dB/Step
1dB/Step
Ref
1N3
1N4
10dB/Step
10dB/Step
1dB/Step
1dB/Step
Ref
1N5
1N6
CODE1
CODE2
DGND SDA SCL GND
10dB/Step
10dB/Step
1dB/Step
1dB/Step
Ref
Ref
Control unit
VOLUME CONTROL IC PT2258
Manufactured by CMOS technology,6-channel volume control IC.I2 C control interface
Features:
6-channel design, each channel 0-79 dB 1dB/STEP
Working voltage:+5~8v
Audio channel separability: 100dB
2
I C control interface
DIP package
SP550S SERVICE MANUAL

11
OUT 3
OUT 4
VCC
INPUT 3
INPUT 4
CLIP DET
S-GND
PW-GND
STAND-BY
SUR
INPUT 2
INPUT 1
VCC
OUT 2
OUT 1
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
Pin connection (Top view)
CPU IC AT89C2051 POWER IC TDA7370B
8-bit microprocessor 4-channel audio amplifier
RST/VPP
(RX1) P3.0
(TX1) P3.1
XTAL2
XTAL1
(INT0) P3.2
(INT1) P3.3
(T0) P3.4
(T1) P3.5
GND
1
2
3
4
5
6
7
8
9
10
20
19
18
17
16
15
14
13
12
11
VCC
P1.7
P1.6
P1.5
P1.4
P1.3
P1.2
P1.1 (AIN1)
P1.0 (AIN0)
P3.7
PDIP/SOIC
Pin structure
Features:
Voltage:+2~+6v Max.+6.6v
Max. I/O current:20mA
I/O numbers:15
RAM:128 bits
FLASH EEPROM:2K
Features:
Voltage:+18V Max.+28V
Max. peak current:3.5A
Output Power(Vs=14.4V Rl=4 ohm,THD=10%,f=1kHz
6.5w*4
Full protection function
Max. work efficiency :24 MHz
THE EXPLANATION FOR KEY COMPONENTS
SP550S SERVICE MANUAL

12
SUPPLY VOLTAGE
OUTPUT
GROUND
INVERTING INPUT
NON INVERTING INPUT
5
4
3
2
1
GND
TAB CONNECTED TO PIN.3
Pin connection (Top view) Connection Diagram (Front View)
VCC
OUTPUT
-VEE
-IN
+IN
5
4
3
2
1
POWER IC TDA2003 POWER IC LM1875
Mono audio power amplifier Mono power amplifier
Features:
Max. output current:4A
Full protection function
Output Power:(Vcc=+25v, V =-25v,
EE Rl=8ohm
THD=1%,f=1kHz):25w
Features:
Voltage:+18v,Max.+28v
Max. output peak current:3.5A
Output power(Vs=14.4v,RL=4 ohm,THD=10%,f=1kHz):6w
Full protection function
THE EXPLANATION FOR KEY COMPONENTS
SP550S SERVICE MANUAL
Voltage: 8V~30V