Akai QX-3700 User manual

SERVICE MANUAL
Model:
QX3700
MINI HIFI
MICRO COMPONENT SYSTEM
www.akai.ru

STANDBY/ON
LOUDNESS
PHONES
REMOTE
FUNCTION
UP/RDOWN/L
Hi-Fi MICRO COMPONENT SYSTEM
VOLUME
QX-3700QX-3700
QX-3700QX-3700
QX-3700
Mini Hi-Fi Micro Component System
SERVICE MANUAL

- 1 -
This manual is the latest at the time of printing, and does not include
the modification which may be made after the printing, by the
constant improvement of product.
Contents
I.Safetyinstructions................................................................................................................. 2
II.Specifications...................................................................................................................... 3
III.LevelListofEquipments& Instruments Required forProduction.......................................... 6
IV. Block diagram.................................................................................................................... 7
V. Wiring diagram ................................................................................................................... 8
VI. Schematic Diagram ..........................................................................................................9
VII.ComponentDiagrams ..................................................................................................... 10
VIII.Exploded Diagram View and PartsList .......................................................................... 18

- 2 -
I. Safety instructions
When using electric products, basic precautions should always
be followed, including the following:
1. Read Instructions – All the safety and operating instructions
should be read before the appliance is operated.
2. Retain Instructions – The safety and operating instructions
should be retained for future reference.
3. Heed Warnings – Adhere to all warnings on the appliance
and in the operating instructions.
4. Follow Instructions – All operating and use instructions
should be followed.
5. Water and Moisture – The appliance should not be used near
water-for example, near a bathtub, wash-bowl, kitchen sink,
laundry tub, in a wet basement, or near a swimming pool, etc.
6. Carts and Stands – The appliance should be used only with
a cart or stand that is recommended by the
manufacturer. An appliance and cart
combination should be moved with
care. Quick stops, excessive force,
and uneven surfaces may cause the
appliance and cart combination to
overturn.
7. Wall or Ceiling Mounting – The appliance should be mounted
to a wall or ceiling only as recommended by the manufacturer.
8. Ventilation – The appliance should be situated so that its lo
cation or position does not interfere with its proper ventilation.
For example, the appliance should not be situated on a bed,
sofa, rug or similar surface that may block the ventilation open-
ings; or placed in a built-in installation, such as a bookcase or
cabinet that may impede the flow of air through the ventilation
openings.
9. Heat – The appliance should be situated away from heat
sources such as radiators, heat registers, stoves, or other ap
pliance (including amplifier) which produce heat.
10. Nonuse Periods – The power cord of the appliance should
be unplugged from the outlet when left unused for a long pe
riod of time.
11. Power Sources – The appliance should be connected to
a power supply only of the type described in the operating
instructions or as marked on the appliance.
12. Power Lines – An outdoor antenna should be located away
from power lines.
13. Power Cord Protection – Power-supply cords should be
routed so that they are not likely to be walked on or pinched
by items placed upon or against them, paying particular atten-
tion to cords, at plugs, convenience receptacles, and the point
where they exit from the appliance.
14. Power requirements for multi voltage (not for all mod
els) – Before connecting the power cord, make sure that the
voltage selector on the rear panel is set to the correct voltage
for you area. If not, please set it correctly.
15. Load – For protecting the appliance from being damaged, rated
load while is printed on the appliance or is explained in opera-
tion instruction, that should be connected to the speaker out-
put of the appliance. Never short circuit the speaker output of
the appliance when the appliance is working.
16. Object and Liquid Entry – Care should be taken so that
objects do not fall and liquids are not spilled into the enclosure
through openings.
17. Cleaning – Unplug the appliance from the wall outlet before
cleaning. Do not use liquid cleaners or aerosol cleaner. Use a
damp cloth for cleaning.
18. Make your contribution to protect the environment –
Used batteries with the ISO symbol for recycling as well as
small accumulators (rechargeable batteries),
mini-batteries (cells) and starter
batteries should not be thrown into
the garbage can. Please leave them
at an appropriate depot.
Portable cart warning
19. Overloading – Do not overload wall outlets and extension
cords as this can result in a risk of fire or electric shock.
20. Damage Requiring Service – Unplug this appliance from the
wall outlet and refer servicing to qualified service personnel
under the following conditions:
a). The power-supply cord or the plug has been damaged;
b). Objects have been fallen, or liquid has been spilled into
the appliance;
c). The appliance has been exposed to rain;
d). The appliance does not appear to operate normally or ex-
hibits a marked change in performance;
e). The appliance has been dropped, or the enclosure dam
aged.
WARNING
TO REDUCE THE RISK OF FIRE OR ELECTRIC SHOCK, DO
NOT EXPOSE THIS APPLIANCE TO RAIN OR MOISTURE.
CAUTION
TO REDUCE THE RISK OF ELECTRIC SHOCK, DO NOT
REMOVE COVER (OR BACK). NO USER SERVICEABLE
PARTS INSIDE. REFER SERVICING TO QUALIFIED SERVICE
PERSONNEL.
The lightning flash with arrowhead symbol,
within an equilateral triangle, is intended to
alert the user to the presence of uninsulated
“dangerous voltage” within the product’s
enclosure; that may be of sufficient magnitude
to constitute a risk of electric shock to persons.
The exclamation point within an equilateral
triangle is intended to alert the user to the
presence of important operating and
maintenance (servicing) instructions in the
literature accompanying the appliance.
CLASS 1 LASER PRODUCT
This product contains a low power laser device. To ensure
continued safety, do not remove any covers or attempt to gain
access to the inside of the product. Refer any servicing to qualified
personnel.
A. CLASSIFICATION LABEL, PLACED ON EXTERIOR SURFACE
B. WARNING LABEL, PLACED INSIDE THE UNIT
RISKOFELECTRICSHOCK
DONOTOPEN
CAUTION
CLASS 1 LASER PRODUCT
KLASSE 1 LASER PRODUKT
LUOKAN 1 LASER LAITE
KLASS 1 LASER APPARAT

- 3 -
II. Specifications
CONDITIONS OF SPECIFICATION MEASUREMENTS
1. STANDARDS ENVIRONMENTAL CONDITIONS
TEMPERATURE : 23°C
HUMIDITY : 65%
IF NO DOUBT ARISES IN THE JUDEMENT, THE MEASUREMENT CAN BE MADE UNDER
CONDITIONS OF TEMPERATURE 10 TO 35°C AND HUMIDITY 45 TO 85%.
2. REATED POWER SUPPLY AC: 220V 50Hz
3. LOAD IMPEDANCE
SPEAKER OUTPUT : RESISTIVE LOAD AS SPECIFIED.(4 OHM)
PREAMPLIFIER OUTPUT AND RECORDING OUTPUT : 47k OHM RESISTOR (± 5%)
VIDEO OUTPUT: 75 OHM
4. STANDARD OPERATING CONDITION AND METHOD OF MEASUREMENT
a) OPERATION METHOD, SETTING POSITION OF THE UNIT STARTING CONDITION
FOR THE MEASUREMENT SHOULD BE MAINTAINED FOR TESTS OF AMPLIFIER
SECTION AS EIA-RS-490, FOR TEST OF TUNER SECTION AS IHF-T-200.
b) EXCEPT AS OTHERWISE SPECIFIED HEREIN, ALL TESTS SHALL BE MEASURED AT
FRONT CHANNELS AND SET THE SELECTOR POSITION.
c) MODULATION OF FM DODE 75KHz DEVIATION AUDIO 1KHz 75 OHM
d) MODULATION OF FM STEREO MPX. 67.5KHz DEVIATION
7.5KHz PILOT
AUDIO 1 KHz
e) MODULATION OF MW 30% MOD. AUDIO 1KHz
f) REF. OUTPUT LINE OUT
Specifications
1. FM Section
FM Electrical Specifications (Text Point at Line Out)
Measurement Specifications Measurement Condition/Method/Remarks
Description 1HF FM Measu. SSG Others
BPF MODE Freq. Level
FM RANGE 87MHz~108MHz
30dB S/N ≤20uV Mono 98MHz Adjust
AUTO STOP 30±5dBuV Auto 98MHz Adjust Output level ratio of modulation
SENSITIVITY OFF to ON Pilot : ON, R ch :
ON
OUTPUT LEVEL 0.50±0.1Vrms Yes Mono 98MHz 60dBu Measure both channel test
point at Line Out
STEREO ≥20dB Yes Auto 98MHz 60dBu
SEPARATION
MEASURED MODE

- 4 -
2. MW Section
i. MW Measurement Condition
(a) Antenna Input : Loop Antenna
(b) Measurement Frequency : Lower Center Upper
All versoin 603kHz 1008kHz 1404kHz (In case of no comment, measure at
center frequency.)
(c) Modulation Frequency : In case of no comment, use 1kHz 30% modulation
(e) Selectivity : Arithmetical mean of 2 values at ±10kHz deviated frequency
(f) Measurement Point : Test Point (At line out)
ii. MW Electrical Specifications
Measurement Specifications Measurement Condition/Method/Remarks
Description Meas.Freq. SG Level Others
AM RANGE 522KHz~1611KHz
26dB S/N ≤5.0mV/M Center Adjust Output level ratio of
modulation OFF to ON
AUTO STOP 20mV/M Center Adjust Minimum input level of Auto Stop
SENSITIVITY ≤Auto Stop Sensitivity threshold
≤5.0mV/M
OUTPUT LEVEL 150-500MVrms Center 10mV/M Measure both channel test point
at Line Out
3. VCD Section
VCD Measurement Condition
Measurement Point: At line out or video out
1. Electrical Specifications
No. Test Item Unit Specification
1 Video Output Level Vp-p 1.0±0.2
2 Audio Output Level Vrms 2.0+0.2/-1.0
3 Audio of Resp (20Hz~20KHz) dB ≤±3.5
4 Audio S/N (A-WTD) dB ≥70
5 Distortion & Noise (1KHz) dB ≤-50
6 Cross Talk L-R (Fundamental) dB ≥60
2. Mechanical Specifications
No. Test Item Unit Specification
1 Reading Time S <20 (S)
2 Ball Bound:
Drop 8g Super Ball from 3cm Height No AV Noise

- 5 -
4. AMPLIFIER Section
i. AMPLIFIER Measurement Condition
(a) Power Output : Measure without pre-heating
(b) Source Impedance : Normally 600
(c) S/N : Measure the noise level without low frequency ( 80Hz) vibration
(d) Frequency Response : Measure at -10dBs output (1kHz) by adjusting oscillator output
(e) Difference of L/R ch : The output level difference between L ch and R ch at ± 3dB output
(f) Other : In case of no comment, set volume maximum and 4 load
ii. AMPLIFIER Specifications
Measurement Specifications Measurement Condition/Method/Remarks Measurement
Description Test Input Input Signal Output Vol. Method/Remarks
Point Selector Freq. Level Level
Power Output 15±3W SP out Line 1kHz Adjust Adjust MAX Both channel drive/
front THD 2% 4 load
Distortion Less than 2% SP out Line 1kHz Adjust 12W MAX Both channel drive/
4load read best
value when indicator
of distortion meter is
changing
Line Input 200±50mV SP out Line 1kHz Adjust Adjust MAX
Sensitivity THD 2%
S/N ≥65dB SP out Line 4.7k 5W MAX
Terminate
Channel more than 30dB SP out Line 1kHz Adjust 5W MAX Measure a ratio of
Separation leak level of L R,
RL; Measured
channel input terminal
AUX: 4.7k Terminate
Frequency ±2dB SP out Line 80Hz Adjust +3dBs MAX Measure the level
Response 12.5kHz difference
Loudness +10dB±5dB H:10KHz Line 1KHz Adjust --- 30Bar Difference from 1KHz
L:100Hz out
Line Out 80±20mV Line out Line 1KHz Adjust Adjust MAX
Level THD 2%

- 6 -
Measurement Specifications Measurement Condition/Method/Remarks Measurement
Description Test Input Input Signal Output Vol. Method/Remarks
Point Selector Freq. Level Level
Frequency - 5.0 dB ± 3.0dB SP AUX 10Hz Adjust 0dBs MAX Measure the level
Response - 4.0 dB ± 3.0dB OUT 100kHz difference from 1kHz
output
Super Bass + 10dB ± 3.0dB SP AUX 70Hz Adjust 0dBs 30 Measure the level
OUT difference ( S BASS
ON)-(S BASS OFF)
at 1kHz Volume
Level 30 Position
Loudness Low + 6.0 dB ± 3.0dB SP AUX 100Hz Adjust 0dBs 30 Volume Level 30
Equalizer - 10.0 dB ± 3.0dB OUT Position
High + 5.0 dB ± 3.0dB 10kHz
- 7.0 dB ± 3.0dB
NO. Designation Requirement Reference Model Remark
1 Standard signal EXT. MOD. Input LEADER 3216 1 set
Generator Modulation: AM 0-60%
FM 0-99.9KHz
Frequency: 0.1-140MHz
Level: -20-120dBu
Output: 1-50W
2 AC voltmeter Inter Resistance 1M-10MW KENWOOD V7-171 2 set
3 Automatic VP7702C 1 set
Distortion Meter
4 CD Player NF3346A 1 set
Evaluation Filter
5 Multiplex Signal KIKU SUI 3400S 1 set
Generator
6 Oscilloscope Max Frequency of input signal; KENWOOD CO-1305 2 set
5MHz
7 Oscillator Frequency of output signal; KENWOOD AG-203A 2 set
20Hz-20kHz
8 Test Loop Resistance: 50 LEADER LPA-070 1 set
Frequency: 100KHz~30MHz
9 WOW FLUTTER MEGURO 1 set
METER MK-668G
III. Level List of Equipments & Instruments Required for Production

MASTER
DGND
7805
LM1876B
LM1876A
7812
2N5401
T4A
AC220V IN
JRC4558B
JRC4558A
REM FUCTION
STAND
LOUD
VOL
VOL
TO VCD
TO VCD
TO CPU
D5V
SW
PHONES
RCH LCH
LINE2 OUT
LINE1 OUT
+12V
8V
D5V
-12V
7808
7805
-22V
AG
+22V
T
SYSTEM CONNECTION
25100-3A08
VFD
+5V
DG
REM
TU
SW
STB
CLK
DI
DO
PT16311
SW
VOL
VOL
MUTE
STAN
MENU
AG
+12V
DATA
AUX
L
R
TUNER
T-933-2
FMAM
LGR
TUN CE DI DO CLK
VCD MEPEG DECODER
L G R V G
DO
STB CLK DG REM
+8V
DG
+5V
VIDEO OUT
V2
V1
AUDIO OUT
PT2314
SYSTEM CONNECTION
78E54
L
R
DO
DI
CLK
CE
+22V
-22V
-21V
F1
F2
0V
MUTE
LEVEL
STAN
MENU
AC10V
AC17V
0V
AC17V
AC3V5
AC3V5
0V
AC17V
AC220V
AC220V
AC12V
AC12V
AC10V
IV. Block diagram
- 7 -

V. Wiring diagram
- 8 -

R710
180
W505
P505 P501
W501
R501
4K7
R503
4K7
R502
4K7
P700
P701
C730
152
L700 1.8uH
R724
100K
R712
100K
R713
100
R715
100
C707
10U
C706
10U
C715
100P
R711
68K
C703
10U
C702
10U
R705
10K
R706 10K
R707 6K8
C708
10U
C709
10U
R718 10K
R717 10K
R719 6K8
R716 6K8
C704
10U
R703 6K8
R702 5K6
C705
10U
R701 5K6
R700 6K8
N700A
N700B
R704
6K8
R714
8K2
C701
10U
C700 10U
R563
100
W100 P100
W500
W502
GT
GT
GTGT
GTGT
GT
GT
DGND
R604 10K R603 10K R602 10K
R601
10K
C717 100U
VD201
LED
VD203
LED
VD205
LED
VD202
LED
VD200
LED
VD207 IN4148
VD206 IN4148
W201P201
C403
10U
C405 10U
C402
47U R404
1K
C404
47U
R407
1K
C407
100P
R406
3K3
R4053K3
C406
100P
C400
10U
C401
10U
R402
4K7
R403 100K R400 100K R401 4K7
C728 10U
C727 10U
N701B
JRC4558:A
N701A
JRC4558:A
C116
100U
R726 47K
R725 47K
C726
10U
C725 10U
R723
5K6
C722 104
C723 104
C721 104
C724
104
R722
5K6
C712
2U2
C714
272
C713
272
N702
PT2314
C719
2U2
C720
10U
C502
100P
R508
470K
R565 10K
C501
103
R208 100
RP200
EC-16B
R500
10K
C505
30P C504 30P
X500
12MHZ
W104 P104
R307
220K
R306
68K
C303
220U
R304 15K
R305
39K
V302 C1815
V301
C1815
V300
A1015
C201
223
C200
223
R203
680
R200 680
R201
560
R202
560
P202
PHONES
C304 102 C305 102
VD300
IN4148
VD111
IN4148
W200
P200
C301
104
C302
104
R302
4.7
R303
4.7
L302
1UH
L301
1UH
R300
4.7
R301
4.7
C114
100U
C113 100U
VD112
12V
V102
2N5401
V101
C9014
V100
C9014
N104
L7805CV
N100
L7805CV
N101
L7808CV
N103
L7812CV
C53
100U/16V
C52
100U/25V
P101
W101
C125 104
C124
104
C123
1000U
C122
1000U
VD110
IN4001
C120
1000U/25V C121
1000U/16V
C43
470U
C131
103
C130
103
VD107
IN4007
VD106
IN4007
VD105
IN4007
VD104
IN4007
C132
103
C133
103
C129
103
C128
103
C300
0.15K/250V
L300 UT-20
XP300
JK2
OT
IN
N102B
LM1876TFB
N102A
LM1876TFA
C718
22U
C711 104
C710 104
C716 104
VD113
BF40C6A
F101
F3.15A
F300
250V/T4A
F100
F3.15A
C106
2200U/25V
C107
2200U/25V
C137
104
C138
104
C108~C111
103X4
T01
P300
P301
W300
P102
W102
VD100
IN4007
VD101
IN4007
VD109
IN4007
VD108
IN4007
VD400 IN4007
VD102
IN4007
VD103
IN4007
C126
103
C127
103
C408
220U/35V
R408100 R409100
R41010k
VD401
22V
VD402
5V1
C409
104
R111
10K
R112
100
R110
100
R106
470/3W
R107
100/3W
C115
220U/25V
C112
220U/25V
R108 3K3
C100
4U7
C101 4U7
R100
22K
R3
22K
C104 330P
R104
24K
W104 P104
C105 330P
R105
24K
R102
1K
R103
1K
C102
47uC103
47u
P503W503
R512
4K7X8
R513
4K7X8
VD500
IN4148
C503
10U
C506
104
R509 22K
V503 C9014
V502
C9014
R564
22K
R560 33K
N502A
JRC4558
N502B
JRC4558
R561 22K
N400B
JRC4558:B
N400A
JRC4558:A
R220 150
K202 R222
18
R210 100 R205 100
K200 R209
100
K201 R204
100
V201
C9014
V202
C9014
V200
C9014
R206
33K
C205 104
R212
10K
R213
10K
R214
180
R207
1K
R211 33K
R215
180
C206
104
R216
180
R217
180
R218
180
R221
100
C203
104
C204
47U
C202
47P
VD600
IN4148
VD601
IN4148
VD603
IN4148
VD602
IN4148
AN
AN
AN
AN
AN
AN
AN
N601
24C02
VD204
LED
R720 47K
R721
47K
R709
68K
C729
100p
R708 8K2
C731
10U
C732
10U
DG
N500
SYSTEM CONNECTION
CON26P
FROM
LCH AG RCH
+12V
OUTPUT
FROM
V DG
AG
V2 V1 R L
VIDEO OUT AUDIO OUT
TO VCD MPEG
DG
+8V
DG
+5V
HRS2H-S
RL300
6A/250V
TO TUNER
CLK
DO
DI
TUN
CE
TUN SW STB CLK
DI DO
K1
P17 P16 P15 P14 P13 P12 P11 P10 P9 P8 P7 P6 P5 P4 P3 F2 F2 F1 F1 P2 P1 G7 G6 G5 G4 G3 G2 G1
+5V
DGND
VOL2
VOL1
STAND
8
7
6
5
4
3
21
DG DG AG
7
6
5
3
21
4
8
BOUR BINR BOUL BINL LOUT
LIN
VCDR
VCDL
TUNL
AUXL
LOUL
TURN
AUXR LOUR ROUT RIN TRR TRL AGND VCC
REF
DI DO DG
R L
3
2
1
89C58
F2 F1 -21V 0V
RCHLCH SPEKEAR OUT
LIN LOUT AGND RIN ROUT
RL100
HRS2H-S
VCD
R L
R
L
TUNER
AUX IN
DI DO
+12 -12
RCH LCH GND
8
73 1
45
6
9
14 10
11
15
13
12
2
MUTE CONTROL
LIN
AGND
RIN +8V
DG DG
+5V
MUTE
+22V
-22V
LOUT
LGND
RGND
ROUT
+12V
DGND
CPU POWER
DGND
VCD
+5V -12V DGND +12V
P00
P01
P02
P03
P04
P05
P06
P07
P20
P21
P22
P23
P24
P25
P26
P27
ALE/P
PSEN
P10
P11
P12
P13
P14
P15
P16
P17
CE
MENU
REMIN
STB
VOL1
MUTE
STAN
REST
X2 GND
39
38
37
36
35
34
33
32
21
22
23
24
25
26
27
28
30
29
17
16
9
1
2
3
4
5
6
7
8
11
10
12
13
14
19
18
DO
STB
CLK
REM
DGND
15 VOL2
X1
20
31
VCC
+5V
SW
MENU
VOL1 VOL2
MUTE STAN+8V +5V
AG
RCH
LCH
-12V
+12V
REM
-21V
F1 F2 DG DG
FC-26P
CON26P2
IR200 1838
REM
GND
PT16311
N600
+5V
-21V
VDD
GR5
GR4
GR3
GR2
GR1
SW1 SW2 SW3 SW4 DO DI NC CLK STB K1 K2 K3 K4
KS12
KS1
KS2
KS3
KS4
KS5
KS6
KS7
KS8
KS9
KS10
KS11
GR8 GR7 GR6
SG20 SG19 SG18 SG13
VDD
SG17 SG16 SG15 SG14
LED5
LED4
LED3
LED2
LED1
OSC
GND
K4 K3 K2
KS5
KS4
KS2
KS1
K601
K600
K603
K606 K602
K605K604 DI DO
+5V
+5V
+5V
DG DG F2 F1 -V
+12V
-12V
L R
AG
+5V
+8V STAN
MUTE VOL2 VOL1
SW
AG DG DG
+5V
+5v
VFD600
25100-3A08
LEVEL
LEVEL
-12V
+12V
VCC 40
REMO
250V
250V
TO VCD MPEG
VI. Schematic Diagram
- 9 -

VII. Component Diagrams
i. AMP PCB Component Diagram
- 10 -

ii. AMP CONTROL PCB Component Diagram
- 11 -

iii. AMP OUTPUT PCB Component Diagram
- 12 -

- 13 -
iv. CONNECTIVE PCB Component Diagram

v. CPU CONTROL PCB Component Diagram
- 14 -

- 15 -
vi. VCD CONTROL PCB Component Diagram

- 16-
vii. AUDIO/VIDEO OUTPUT PCB Component Diagram

- 17-
viii. REMOTE HANDSET PCB Component Diagram

- 18 -
VIII. Exploded Diagram View and Parts List
A. VCD exploded