Daewoo Akf-0275 Service Manual
Service Manual
Car Audio Basic, RDS & OIRT Band
S/M No:AKF0275EF0
MODEL : AKF-0275 Series
AKF-0285 Series
DAEWOO ELECTRONICS CO., LTD
http://svc.dwe.co.kr Jan. 2000
4-Channel High Power (35W x 4Ch)
Electronic Tuning
Electronic
Volume /Bass /Treble /Balance /Fader Controls
Auto Memory/Preset Scan
Repeat/Random/Intro Scan
Local/DX Switch
Loudness & Mute Controls
Flip-Down Detachable Face for Anti-Theft
TABLE OF CONTENTS
1.
PRODUCT SPECIFICATIONS
..................................1
2. LINE DRAWING .............................................2
3. ADJUSTMENTS ...........................................5
4. SCHEMATIC DIAGRAM ..................................10
5. PARTS LOCATION ON P.C. BOARD .............................13
6. OVERALL EXPLODED VIEW & PARTS LIST ....................15
7. DECK MECHANISM EXPLODED VIEW & PARTS LIST .......17
8. PARTS LIST .............................................20
9. FUNCTION OF MICOM IC ..................................22
10. IC BLO C K DIAGRAM ..................................28
11. LIQUID CRYSTAL DISPLAY .............................32
12. OUTPUT CONNECTION DESCRIPTIONS ....................34
- 1 -
1. PRODUCT SPECIFICATIONS
1-1. TECHNICAL SPECIFICATION
Power requirements : DC 12.0V / Rated : 14.4V
(Usable : 10.8 ~15.6V)
Negative ground
Current consumption : 10A Maximum
Dimension (W x H x D) : Body 178 x 50 x 165 mm
: Escutcheon 188 x 58 x 15 mm
Weight (Net) : 2.7 kg
Design and specifications are subject to change for improvements without notice.
AUDIO SECTION
Maximum output power : 35watts per channel into 4 ohms.
Load impedance : 4 ohms
Total harmonic distortion : Less than 10% at 12 watts
Frequency response : 100Hz( + 3
dB
), 10kHz(-5 +3dB)
TAPE SECTION
Track format : 2-track / 2-channel system
Tape speed : 4.75cm/sec
Wow / Flutter : 0.35% max. (WRMS)
Signal to Noise ratio : More than 50
dB
Channel Separation : More than 35
dB
Frequency response normal (LH)tape
: 63Hz to 10kHz ( + 3dB)
TUNER SECTION
(FM) Tuning range : 87.5 to 108MHz
87.5 to 107.9 at U.S.A
Usable Sensitivity(MONO) : 10
dB
u
(4uV/75ohms)
Stereo Separation : 30
dB
Signal to noise ratio (at 60dBu)
: More than 50
dB
(MW) Tuning range : 522 to 1620kHz at Europe
530 to 1710kHz at U.S.A
Usable Sensitivity : 28
dB
u
(LW) Tuning range (*option) : 144 to 288kHz
Usable Sensitivity : 40
dB
u
1-2. GENERAL SPECIFICATION
2. LINE DRAWING
WITHOUT RDS FUNCTION
: BASIC
WITH RDS FUNCTION
: RDS
2-1. AKF-0275 FRONT SIDE
- 2 -
LINE DRAWING
2-2. AKF-0285 FRONT SIDE
- 3 -
WITHOUT RDS FUNCTION
: BASIC
WITH RDS FUNCTION
: RDS
LINE DRAWING
- 4 -
2-3. AKF-0275/AKF-0285 REAR SIDE
3.
ADJUSTMENTS
- 5 -
3-1. CONNECTIONS EQUIPMENTS
ADJUSTMENTS
3-2. ADJUSTMENT LOCATIONS IN TUNER MODULES
- 6 -
ADJUSTMENTS
3-3. AM (MW/LW) ADJUSTMENT
- 7 -
STEP
1 Band Covering
RF-Tracking
Figure 1
Figure 2
Figure 2
Figure 1
Figure 2
522KHz 60dBu
Mod 1000Hz 30%
603KHz 30dBu
Mod 1000Hz 30%
1404KHz 30dBu
Mod 1000Hz 30%
144KHz 60dBu
Mod 1000Hz 30%
220KHz 60dBu
Mod 1000Hz 30%
522KHz
603KHz
1404KHz
144KHz
220KHz
Adjust AM OSC
for 1.2-1.35V(VT)
Fig.8
Adjust AM RF1 and
AM RF2
for maximum output
Fig.8
Adjust AM RF1 and
AM RF2
for maximum output
Fig.8
Adjust LW OSC
for 1.2-1.35V(VT)
Fig.8
Adjust LW RF1 and
LW RF2
for maximum output
Fig.8
RF-Tracking
LW Band Covering
LW-Tracking
2
3
4
5
DESCRIPTION
CONNECTION
ANTENNA SIGNAL
DIAL
CONTROL
ADJUSTMENT
1. Dummy Antenna Circuit
2. Location of Adjustment Points
Refer to Adjustment Location Page
3. Control Setting
Power Switch
.............
ON Balance/Fader Control
................
Mech. Center
Band Switch
..............
AM Treble/Bass Control
...................
Mech. Center
Other
......................
OFF
4. Adjustment Procedure
NOTE:
When it is U.S.A band instead of 522, 603, 999, 1404kHz is 530, 600, 1000, 1400kHz
ADJUSTMENTS
3-4. FM ADJUSTMENT
- 8 -
STEP
1 IF (Zero Volt)
RDS Receiving
estimation level
Figure 3
Figure 4
Figure 5
Figure 5
98.1MHz 60dBuV
No Modulation
98.1MHz 42dBuV
Mod.
1kHz 30% Mono
98.1MHz 60dBuV
Mod.
1kHz 30% Stereo Left
at Right ch.
98.1MHz 35dBuV
Mod.
1kHz 30% Stereo Left
at Right ch.
98.1MHz
98.1MHz
98.1MHz
98.1MHz
Adjust FM DET
for 0V + 0.03V
Fig.8
Adjust RV 101 Tuner PC
Board for2.7V=20mV at
TP102(IC401 pin 66)
Adjust MPX SEP
Fig.8
for maximum separation
Left and Right ch.
Adjust Stereo Blend
Fig.8 1dB separation
between Left and Right
ch.
Stereo Separation
SNC
4
5
6
DESCRIPTION
CONNECTION
ANTENNA SIGNAL
DIAL
CONTROL
ADJUSTMENT
1. Dummy Antenna Circuit
2. Location of Adjustment Points
Refer to Adjustment Location Page
3. Control Setting
Power Switch
.............
ON Balance/Fader Control
................
Mech. Center
Band Switch
...............
FM Treble/Bass Control
..................
Mech. Center
Other
......................
OFF
4. Adjustment Procedure
ADJUSTMENTS
3-5. TAPE ADJUSTMENT
NOTE : 1. Clean the playback head before adjustment
2. Prepare the test tape MTT-144 or equivalent
3. Balance, Fader, Bass & Treble ....Center position. Volume adjusted to 2Volts.
Note
: dBu uV
dBuV uV
17 5.0 33 44.6
16 6.31 35 56.2
30 31.6 45 178
NOTE : Antenna signal is used.
1. For Signal Generator with readings in
EMF(Open type) add 12dB (6dB for the
“Dummy” and 6dB for EMF-reading).
2. For Signal Generator with reading in dBm add 6
dB for “Dummy”
STEP
1
Head azimuth
adjustment
Tape Speed
Figure 6
Figure 6
MTT-144N
or equivalent
MTT-144N
or equivalent
Speaker
Output
Speaker
Output
Head azimuth
adjustment screw
Turn the azimuth
screw to obtain
maximum level
Adjust for 30103020Hz
Tape Speed
adjustment
2
DESCRIPTION
TEST TAPE
CONNECTION
TEST
POINT
ADJUSTMENT
POINT
ADJUSTMENT
- 9 -
4. SCHEMATIC DIAGRAM
4-1. BASIC Series AKF-0275/0285
- 10 -
Size:A3
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