Kenwood RXD-251 User manual

MINI HiFi COMPONENT SYSTEM
RXD-251/301/301E/301W/
RXD-351/351E/351W/371S/A3
SERVICE MANUAL
© 1998-7/B51-5454-00 (K/K) 3763
(XD-251~A3)**
In compliance with Federal Regulations, following are reproduc-
tions of labels on, or inside the product relating to laser product
safety.
**Refer to page 2 if you want to know system configuration.
KENWOOD-Crop. certifies this equipment conforms to DHHS
Regulations No. 21 DFR 1040. 10, Chapter 1, Subchapter J.
DANGER : Laser radiation when open and interlock defeated.
AVOID DIRECT EXPOSURE TO BEAM
Panel(CD) *
(A60-)
Front glass *
(A29-)
Knob *
(K29-)
Knob
(K29-7512-08)
Knob
(K29-7519-08)
Knob
(K29-7518-08)
Phone jack
(E11-0386-08)
Konb
(K-29-7516-08)
Cassette lid(R) *
(A53-)
Front glass(R)
(B10-3451-08)
Front panel *
(A60-)
Knob *
(k29-)
Knob
(K29-7523-08)
Knob
(K29-7522-08)
Knob
(K29-7521-08)
Cassette lid(L) *
(A53-)
Front glass(L)
(B10-3450-08)
Knob
(K29-7515-08)
Knob
(K29-7511-08)
Mic jack
(E11-0387-08)
Knob *
(K29-)
Knob *
(K29-)
Knob
(K29-7513-08)
Illust. is RXD-351.
* Refer to parts list on page 38.

FM indoor antenna (1)
Europe and U.K. Other countries
AM
(T90-0815-08)
loop antenna (1)
AC
(E03-0115-05)
plug adaptor (1)
Remote
(A70-1260-08)
control unit (1)
Batteries (R6/AA) (2)
Use to adapt the plug on the power cord
to the shape of the wall outlet.
(Accessory only for regions where use is
necessary.)
(T90-0801-05)
: K1P1Y1M1M2M3X1X2X3
(T90-0836-05)
: E1E2E3E4T1T2Q1Q2
Operation to reset
The microcomputer may fall into malfunction (impossibility to oper-
ate, erroneous display, etc.) when the power cord is unplugged
while power is ON or due to an external factor. In this case, execute
the following procedure to reset the microcomputer and return it to
normal condition.
Press the "POWER" key while holding the Stop (7) key of
the CD section pressed, to switch off the power, and then
switch the power on again after a few seconds.
÷ Please note that resetting the microcomputer clears the contents
stored in and returns and to condition when it left the factory.
SYSTEM MAIN UNIT DESTINATION SPEAKER
XD-301 RXD-301 E3T2X3 LS-N301
XD-301E RXD-301E E4 LS-N301
XD-301W RXD-301W Q2 LS-N301
XD-351 RXD-351 E1T1 LS-N351
XD-351 RXD-351 M1X1Y1 LS-N371
XD-351E RXD-351E E2 LS-N351
XD-351W RXD-351W Q1 LS-N351
XD-A3 RXD-A3 K1P1 LS-N351
XD-371S RXD-371S M2 LS-N371
XD-251 RXD-251 M3X2 LS-N351
RXD-251/301/351/371S/A3
2
CONTENTS / ACCESSORIES
CONTENTS / ACCESSORIES ....................................2
EXTERNAL VIEW........................................................3
CONTROLS.................................................................4
BLOCK DIAGRAM.......................................................6
CIRCUIT DESCRIPTION.............................................7
CD MECHANISM OPERATION DESCRIPTION .........9
ADJUSTMENT.......................................................... 11
WIRING DIAGRAM....................................................15
PARTS DESCRIPTIONS...........................................16
PC BOARD ................................................................17
SCHEMATIC DIAGRAM............................................23
EXPLODED VIEW .....................................................37
PARTS LIST...............................................................38
SPECIFICATIONS.....................................................47
Contents
Accessories
System configuration Cautions

RXD-251/301/351/371S/A3
3
EXTERNAL VIEW
Slide switch
(S62-0083-08)
AC power cord *
(E30-)
Cabinet *
(A01-)
Phono jack
(E63-1073-08)
Slide switch
(S62-0057-08)
Lock terminal board
(E70-0108-08)
Antenna terminal *
(E70-)
Illust. is RXD-351.
* Refer to parts list on page 38.

RXD-251/301/351/371S/A3
4
CONTROLS
CD unit
DISC 1 DISC 2 DISC 3
076
¢

4
DISC
SKIP
12 3 456
7
Receiver unit
ON/STANDBY
INPUT
STANDBY
MIC 1
MIC 2
MIC VOLUME
MIN.
MAX.
TIMER SET
CLOCK
DISPLAY
/DEMO
ROCK
FLAT
EX.BASS
POP
JAZZ
BAND TUNING
PHONES
UP
DOWN
AUTO
PRESET
MANUAL
PRESET
AUTO/MONOTIMER
8
9
0
!
@
#$ %
&
()
¡

™

£

^
*
¢

∞

1 Skip ( 4 , ¢ ) keys
2 DISC SKIP key
Used to skip discs.
3
Disc selection keys
The disc number is selected directly and playback starts.
4
OPEN/CLOSE ( 0 ) key
The disc tray is opened and closed.
5
Stop ( 7 ) key
6 Play/pause ( 6 ) key
7 Disc tray
Three discs can be stored.
8
ON/STANDBY ( ) key
9 INPUT key
Key for input switching.
0
TIMER key
Key for timer START/STOP switching.
!
MIC 1/MIC 2 jack (except for some areas)
@ MIC VOLUME knob (except for some areas)
# TIMER SET key
Used for setting the timer ON/OFF time.
$
CLOCK key
Used to set the present time.
%
DISPLAY/DEMO key
Switches the display contents.
*Used for demonstration (DEMO) ON/OFF.
^
AUTO/MONO key
Switches the tuning mode.
&
MANUAL PRESET key
Used to memorize broadcasting stations in the desired order.
*
BAND key
Press to switch the receiving band.
(
TUNING/ keys
Used for tuning to broadcasting stations and for time settings.
)
PHONES terminal
For connection of a headphone (optional).
¡
AUTO PRESET key
Used for automatic presetting of broadcasting stations.
™
VOLUME CONTROL knob
This is used for volume adjustment.
£
Sound selection keys
Used to select the desired sound type.
FLAT : For listening without changing the sound.
JAZZ : A sound quality curve suitable for jazz.
POP : A sound quality curve suitable for popular
music.
ROCK : A sound quality curve suitable for rock-and-roll.
EX.BASS: For listening with abundant bass. (Can be used
together with other sound selection keys.)
¢ Display
∞ STANDBY indicator (Except for some areas)

RXD-251/301/351/371S/A3
5
CONTROLS

RXD-251/301/351/371S/A3
6
BLOCK DIAGRAM
CE
DI
CL
VREF
24 23 20 19 16 14
1
2 5
9
11
23
3,28 2,29 1,30
+
+
TUNER
CD
AUX
CONTROL
SERIES
DATA
A/B
PLAY
AMP
ALC
PLAY
R/P OSC
BIAS
(Q209,L201)
Q205
Q203 Q204
Q206 Q201Q202
TAPE OUT
TAPE
Q405,406
REC BUFFER
IC402
TAPE OUT REC OUT REC IN
DECK A/B SW
Q213
+B
IC301
MIC AMP
MIC IN
Q403,404
+3dB AMPPRE SET
EQ.
PRE AMP
IC404
EX-BASS
412
Q411,
410
Q409, RL501
Q413,
414
MUTE
SYSTEM 714
-10dB
ATTENUATOR
Q713,
POWER AMP
IC501 +VCC
-VCC Q504-506
DETECTOR
IC502
SPEAKER
PROTECTOR
+12V
512
Q511,
MUTE
JACK
SPEAKER
Lch
HEADPHONES
JK502
Rch
JK501
+5.5V Q702
+7.5V +12V
Q701
Q704
+VCC
SWITCHED
to
X'FORMER
-12V Q709
+12V
-VCC
CN701
D702-705
D701
Q705,
706
Q703
LCD DISPLAY
IC601
u-COM
KEY
MATRIX
CN09
to CD PCB
CN401
to MAIN PCB
RF
AMP FILTER
RC
TUNE AMP
MIX IFT CF1
BUFFOSC
TUNE
AMP
IF CF2
TUNE
AM RF
AMP
RF
Q106
FM SECTION
Q101
PLL
IFT
AM u-COM
IC201
L.P.F
Q107,108
7.2MHz
AM SECTION
V.T.
AM ANT
GND
FM ANT OUT
MIX
BUFF
AMP
TUNE
AM ANT
GND
FM ANT AMP
AM RF
TUNE OSC
ANT RF
IFT
PLL
L.P.F
Q107,108
AMP
RF IC201
u-COM
AMP
Q106
IFT CF1 IF FILTER
AM SECTION
AM
FM SECTION
CF2 OUT
RC
IC102
IC102
TUNE
FM RF
FM
OSC
Q102
GND
IC01 CXA1782BQ
RF SIGNAL PROCESSING/SERVO AMP
PROCESSOR W/DAC
DIGITAL SIGNAL
CD POWER DRIVER
IC03 BA5936S
I/O PORT EXTENSION
IC02 74HC4094
IC04 CXD2508Q
XTL01
33.86MHz
IC15 NJM4558L
OPAMP
MMOTOR
DISC
MOTOR
FEED
M
TRACKING
FOCUS
TRAY MOTOR
T/T MOTOR
SW
LIMIT IN
OUTPUT
AUDIO
CONTROL SW
S01-04
Rch
Lch
u-COM
SUB WOOFER
IC602
-VCC
+VCC
PRE AMP JK601
USED RXD-301(X3)/
RXD-351(M1,X1)/
RXD-371S(M2)
IC201
FM FRONT-END
FM RF IC101
TUNER UNIT
CD MECHA. UNIT
TUNER UNIT
AUDIO UNIT/DISPLAY UNIT
RXD-351
IC401
RXD-A3(K1,P1) TYPE ONLY

No. Name I/O Description Active
HL
1 CE I LC7218, LC75392 CE out
2 ENABLE – No used
3 DI I LC7218, LC75392, 74HC4094 data out
4 DO O Data output to LC7218
5 CLK I LC 7218, LC75392, 74HC4094 clock out
6 DATA O Serial data out to CXD2508Q
7 SQCO I Serial output of SUBQ 80BIT
8 SQCK O Clock output
9 XLAT O Latch output
10 FOK O Focus OK output
11 GND – GND
12 RESET I Reset signal input
13 POWER - DOWN I Power down input
14 SENS I CXD2508Q sens
15 VSS – Vss
16 X1 – Xtal 6.0MHz
17 X2 – Xtal 6.0MHz
18 VDD1 – Vdd
19~22 K1~K4 I Key input (K1~K4)
23, 24 GND – GND
25 MODE - SW2 I Model discrimination (RXD-371S only)
26 MODE - SW1 I Model discrimination
27 SCOR I CXD2508Q Sub - code synch detect
28 COUNT O Track number count signal output
29 REMOTE IN I Remote signal input
30 VR + I VR encoder input A
31 VR - I VR encoder input B
32 PIC - UP I Pick - up SW
33 PIC - DOWN I Pick - down SW
34 DISC - COUNT I Disc counter SW
35 TURNTABLE - SW I Turntable SW
36 TRAY - OPEN I Tray open SW
37 TRAY - CLOSE I Tray close SW
38 N/C – No used
39 VR - 1 O VR step extend out 0, 1 step others
40~51 N/C – No used
52~55 S1 - S4 O Segment out (1~4)
56 VDD2 – Vdd
57 VSS2 – Vss
58~79 S5~S26 O Segment out (5~26)
80~82 BIAS 3~1 – GND
83~86 COM - 0~3 O FL Common 0~3
87 FM - STEREO I FM stereo signal input Mono Stereo
88 SYN REC I Synchro start input
89 VSS3 – Vss
RXD-251/301/351/371S/A3
7
CIRCUIT DESCRIPTION
1. Microprocessor : (IC601, LC867224A-5H71)
1-1 Pin description

PORT SW 1 SW 2 SW 3 SW 4 SW 5 SW 6 SW 7 SW 8 SW 9 SW 10
Pin 19 Power Input Clock Timer Timer Display EQ Off Rock Jazz Pop
(K1) Set Mode Set
Pin 20 Tuning Tuning Band Auto/ Auto Manual EX Bass – – –
(K2) Up Down Mono Preset Preset
Pin 21 CD AMS - – – Disc Disc 1 Disc 2 Disc 3 Open –
(K3) AMS + Skip Close
Pin 22 CD CD Play FF – – – – – – –
(K4) Stop Pause
RXD-251/301/351/371S/A3
8
CIRCUIT DESCRIPTION
No. Name I/O Description Active
HL
90 VDD3 – Vdd
91 POWER - SW O Power SW out On Off
92 SYS - MUT O System mute out Off On
93 TU - MUT O Tuner mute out On Off
94 MODE - SW - IN I No used
95 FUNCTION - TAPE O Function tape out Tape Others
96 LCD - BACK - LIGHT O LCD back light control On Off
97 N/C – No used
98 EX - BASS O EX - bass control On Off
99 LATCH – No used
100 STB O 74HC4094 strobe
PIN NAME I/O DESCRIPTION ACTIVE
4 MUTE O CXD2508Q Muting (DAC) H : ON L : OFF
5 CONTROL O CXA1782BQ, CXD2508Q Vdd control H : Others L : CD
6 XRST O CXD2508Q XRST
7 T • T + O T • T/U • D Motor (+)
11 CONTROL O T • T Motor speed Control
12 TRAY - O Tray Motor Control (-)
13 TRAY + O Tray Motor Control (+)
14 T • T - O T • T/U • D Motor (-)
4. All LCD light on mode
• The all LCD light up when the STOP key and TIMER SET key are pressed simultaneously, while the power is ON.
• When the ON/STANDBY key is pressed, the all LCD light on mode is canceled.
2. Key matrix
3. I/O port extension (CD mecha. unit)
IC02 (74HC4094)

RXD-251/301/351/371S/A3
9
CD MECHANISM OPERATION DESCRIPTION
ROTARY MOTOR
GEAR
PULLEY
RELAY
GEAR A
RELAY
GEAR B
TR LOCK
GEAR
UD-CAM
UD REDUCE
GEAR
CHANGE
GEAR
TURN TABLE
DISC 2 DISC 1
DISC 3
DISC SW
Fig.1
SW C
TRAY MOTOR
Fig.3 Fig.2
2
3
TR GEAR SENSOR SW
(STOP POSITION OF DISC 3)
1. In case of disc 3 (Refer to figure 1 and 2)
1The rotary motor turns counterclockwise by pressing disc 3 key, therefore the turntable turns clockwise and disc 3 is detect-
ed by disc number detector switch.
2The turntable stops the position of 3marked as figure 2 and stop position of disc 3 is detected by sensor switch.
At this time, the position of TR lock gear is as shown figure 1.
3The rotary motor turns clockwise and the relay gear B also turns clockwise.
By turning the relay gear B, the arm of relay gear B moves to arrow direction (2 7 7 7) and the TR lock gear will be
locked.
After that, the change gear separates from TR lock gear.
4The UD reduce gear turns clockwise by turning the change gear.
5The traverse moves up-side.
6After finished the traverse operation, the disc motor turns and the disc 3 will be played.
2. Open/Close operation of tray
while playing the disc.
(Refer to figure 3)
1The tray motor turns clockwise by pressing
open/close key while playing the disc.
2The change base moves to frontward by
turning the TR gear.
3Pushing switch C by change base, the tray
motor stops.

RXD-251/301/351/371S/A3
10
CD MECHANISM OPERATION DESCRIPTION
How to replace the pick up. (Refer to figure 4~7)
1. Remove the screws (1x 4), top chassis and spring (2x 2).
2. Detach the traverse unit by removing shield (bottom side) and screws (3x 2).
3. Short the short land and remove screws (4x 4, 5x 1).
4. Remove the rod and replace the pick up.
1x2
1x2
3x1
3x1
2x2
2x1
Fig.4 Fig.5
BOTTOM VIEW
4x2 4x2
5x1
Fig.7
Fig.6
SHORT LAND
TOP VIEW