Daewoo AKF-3825 Service Manual

Service Manual

Car Audio Basic, RDS

S/M No : AKF8825EF0

MODEL : AKF-3825 Series

AKF-8825 Series

DAEWOO ELECTRONICS CO., LTD

http://svc.dwe.co.kr Apr. 2000

PARTIAL DETACHABLE
LOW POWER (7W x 2 or 4CH)
REMOTE CONTROL
AUTO STOP or REVERSE DECK MECHANISM
ELECTRONIC VOLUME CONTROL
LOUDNESS
LOCAL / DX

TABLE OF CONTENTS

1. PRODUCT SPECIFICATIONS ..................................................1

2. LINE DRAWING ........................................................................2

3. EMERGENCY TROUBLE SHOOT ............................................4

4. ADJUSTMENTS ........................................................................7

5. SCHEMATIC DIAGRAM ..........................................................12

6. PARTS LOCATION ON P.C.BOARD ......................................15

7. OVERALL EXPLODED VIEW & PARTS LIST .......................19

8. DECK MECHANISM EXPLODED VIEW & PARTS LIST .......21

9. PARTS LIST ............................................................................27

10. FUNCTION OF MICOM IC .....................................................31

11. IC BLOCK DIAGRAM .............................................................37

12. LIQUID CRYSTAL DISPLAY ..................................................42

13. OUTPUT CONNECTION DESCRIPTIONS ............................43

1

1. PRODUCT SPECIFICATIONS

AUDIO SECTION

Maximum output power : 7watts per channel into 4 ohms.
Load impedance : 4 ohms
Total harmonic distortion : Less than 10% at 5 watts
Frequency response : 100Hz( + 3dB), 10kHz(-5 + 3dB)
Control Bass/Treble : 10 + 3dB at 100Hz/10kHz

TAPE SECTION

Track format : 2-track / 2-channel system
Tape speed : 4.75cm/sec
Wow / Flutter : 0.35%max. (WRMS)
Frequency response normal (LH)tape : 63Hz to 10kHz

TUNER SECTION

(FM) Tuning range : 87.5 to 108MHz

87.5 to 107.9 at U.S.A

Usable Sensitivity(MONO) : 12dBuV(4

uV

/ 75ohms)

Signal to noise ratio (at 60dBu)

:

More than 50dB

(MW) Tuning range : 522 to 1620kHz at Europe

530 to 1710kHz at U.S.A

Usable Sensitivity : 30dBuV

GENERAL

Power requirements : DC 12.0V / Rated : 14.4V

(Usable : 10.8 ~15.6V)
Negative ground

Current consumption : 3A Maximum
Dimension (W x H x D) : 178 x 50 x 160.5 mm
Weight(Net) : 1.1 kg (AKF-3825) / 1.25Kg (AKF-8825R)

Design and specifications are subject to changes for improvements without notice.

2

2. LINE DRAWING

2-1. FRONT SIDE

AKF-3825 BASIC

AKF-8825 BASIC

AKF-8825 RDS

- Partial detachable

- 2 x 7W

- Remote control

- Auto stop deck mechanism

- Electronic volume control

- Loudness

- Local / DX

- Partial detachable

- 2 x 7W

- Remote control

- Auto reverse

- Electronic volume control

- Loudness

- Local / DX

- Partial detachable

- 4 x 7W

- RDS (AF, PTY, EON, TA)

-

Auto reverse deck mechanism

- Remote control

- Electronic volume control

- Loudness

- Local / DX

3

LINE DRAWING

2-2. REAR SIDE

4

3. EMERGENCY TROUBLE SHOOT

3-1. General Function

No sound from
speakers

Yes

No

Yes

Output connector
is missing

Output connector
is inferior goods

Put exactly output
connector in.

Change output
connector to
superior goods

Yes

No

Power IC, Output
Socket is inferior
goods

Change Power IC,
Output Socket to
superior goods

Yes

A

A

L.C.D or L.E.D
is not turned
off.

Yes

No

Yes

Power is not
supplied

Ref. Point

Output voltage of
power IC is little.

Change Regulator
IC and check
output voltage.

Yes

No

LCD or LED is
inferior goods.

Change LCD or
LED to superior
goods.

Yes

Different each
channel have
output level
(Front, Rear,
Left, Right)

Treble or Bass
is low
unusually

Yes

No

Yes

Balance of front
and rear is in one
side

Balance of Left,
Right is in one
side.

Re-adjust Balance
of front, rear

Ref.

Balance = Center
Front:00 / Rear:00

Ref.

Balance = Center
Left:00 / Right:00

Ref.

Balance = Center
Treble:00 / Bass:00

Ref.

Regulator IC output
Voltage = V

Ref.

Electrical Parts List
L.C.D., L.E.D.

Re-adjust Balance
of Left, Right

Yes

Yes

Balance of Treble
or Bass is in one
side.

Re-adjust Balance
of Treble or Bass

Yes

5

EMERGENCY TROUBLE SHOOT

3-2. Tuner Function

Hearing noise
only

Yes

No

Yes

No selected the
station

Tuner Module is
inferior goods.

Select exactly
broadcasting
frequency.

Change tuner
module to
superior goods.

Yes

Weak frequency
area caused by
elevations

Change to goods of
R.D.S function.

Yes

A

B

A

Station in
other regions
are not held.

Yes Yes

No selected the
local stations.

Ref. Point or

Extreme noise
in broadcast

Weak
separation of
FM stereo

Yes

No

Yes

Antenna
connector is
missing

Put exactly
antenna connector
in his jack

Ref.

CAT-8, KCC-654V
Electrical Parts List

Function of auto­switch noise
reduction

Ref.

Yes

Weak frequency
area of FM, AM

Switch
automatically to
mono mode in
weak frequency
area

Yes

B

R1

In case of located Glass Antenna, check if heat wire is cut or not in rear window.

R2

Check Antenna connector part.

6

EMERGENCY TROUBLE SHOOT

3-3. Tape Function

No sound from
speakers

Yes

No

Yes

Tape is inferior
goods

No signal play
output

Use only superior
goods

Put exactly deck
output connector
in.

Yes

No

Deck Mechanism
is inferior goods.

Change Deck
Mechanism to
superior goods.

Yes

A

A

Sound is low or
not clear

Yes Yes

Head is dirty

Ref. Point

Clean head or
pinch roller with
cleaner

Tape is not
inserted into
the slot.

Some program
is played back
repeatedly

Yes

No

Yes

Tape was inserted
right side left.

Tape is ejected
after being
inserted.

Insert recording
part to right side.

Ref.

Tape Deck Macha
TN-715, TN-301

Ref.

Tape is cut or
extended

Ref.

Check on L.C.D
and press RPT
button.

Yes

Yes

Selected repeat
(RPT) function.

Release RPT
function

Yes

4.

ADJUSTMENTS

7

4-1. EQUIPMENTS CONNECTIONS

ADJUSTMENTS

4-2. TUNER MODULE ADJUSTMENT LOCATIONS

8

ADJUSTMENTS

4-3. AM (MW/LW) ADJUSTMENT METHOD

9

STEP

1 Band Covering

RF-Tracking

Figure 1

Figure 2

Figure 2

522KHz 30dBu

Mod 1000Hz 30%

603KHz 30dBu

Mod 1000Hz 30%

1404KHz 30dBu

Mod 1000Hz 30%

522KHz

603KHz

1404KHz

Adjust AM OSC coil
to reach VT1.2V

Fig.7

Adjust AM RF1 and
AM RF2
for maximum output

Fig.7

Adjust AM RF1 and
AM RF2
for maximum output

Fig.7

RF-Tracking

2

3

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

4-4. FM ADJUSTMENT METHOD

10

STEP

1 IF (Zero Volt)

RDS AF level

Figure 3

Figure 2

Figure 5

98.1MHz 60dBuV
No Modulation

98.1MHz 30dBuV Mod.
1kHz 45KHz DEV.

Mono

98.1MHz 40dBuV
Mod.

1kHz 45KHz DEV.

Stereo Left at Right ch.

98.1MHz

98.1MHz

98.1MHz

Adjust FM DET
for 0V + 0.03V
Fig.3 (CW03)

Adjust RV 101 on main
PC Board
for2.5V+20mV at
TP101(IC401 pin 66)

Adjust Stereo Blend
RV01 on Tuner PCB
Fig.7 10+3dB
separation between Left
and Right ch.

SNC

2

3

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

Note : dBu uV dBu 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”

ADJUSTMENTS

4-5. TAPE ADJUSTMENT METHOD

11

NOTE : 1. Clean the playback head before adjustment

2. Prepare the test tape MTT-114 or equivalent

3. Balance, Fader, Bass & Treble ....Center position. Volume adjusted to 2Volts.

STEP

1

Head azimuth

adjustment

Tape Speed

Figure 6

Figure 6

MTT-114N

or equivalent

MTT-114N

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

12

5. SCHEMATIC DIAGRAMS

5-1. BASIC Series AKF-3825

Size:A3