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©
2002-1 PRINTED IN JAPAN
B51-7880-00 (N)1089
CASSETTE RECEIVER
KRC-4902Y
SERVICE MANUAL
Mounting hardware assy
(J21-9641-13)
Antenna adaptor
(T90-0523-05)
Lever
(D10-4589-04)
DC cord
(E30-4792-05)
Plastic cabinet assy
(A02-1486-13)
LOUD SCRL SCAN REP M.RDMT.CALLB.S/RDM MENU AMEAUTOCLK
KRC-4902
SRC
OFF
45Wx4
WIDE BAND
DISC
AUD
Front glass
(B10-4129-01)
Knob(1-6)
(K25-1392-03)
Knob(SRC)
(K24-3820-04)
Knob(FM,AM)
(K25-1393-03)
Knob(VOL)
(K25-1395-03)
Cassette lid
(A53-1687-03)
Panel assy
(A64-2540-02)
Knob(AUD)
(K24-3821-04)
MECHANISM EXTENSION CORD
W05-0477-00 (7P)
W05-0609-00 (10P)
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KRC-4902Y
3
● SYNTHESIZER UNIT (X14-6892-72)
COMPONENTS DESCRIPTION
Ref.No. Function Operation
IC1 SYSTEM µ-COM
IC2 E-VOLUME
IC4 POWER AMPLIFIER Speaker output
IC7 POWER IC
IC8 MUTE CONTROL LOGIC 3 input NOR gate x 3
IC9 EQUALIZER AMPLIFIER For full logical cassette mechanism control
IC10 SUB MOTOR DRIVER For full logical cassette mechanism sub motor driver
IC11 RESET IC Detection voltage below 3.0V
IC12 EEPROM
Q1 P.CON.DETECTION Detects P.CON voltage.
Q10 BACK-UP DETECTION Detects the back-up voltage.
Q11 SERGE DETECTION Detects serge voltage.
Q20 ACC DETECTION Detects ACC voltage.
Q40 PREOUT MUTE DRIVER Mutes when the base terminal voltage level becomes "L".
Q50 5V SW Works when the base terminal voltage level becomes "L".
Q101 DSI SW LED for DSI works when the base terminal voltage level becomes "H".
Q151 PANEL 5V SW Works when the base terminal voltage level becomes "L". Supplies VDD to panel.
Q221-224 PREOUT MUTE Mutes when the base terminal voltage level becomes "H".
Q251 POWER IC SVR SW Discharges the capacitor's voltage of SVR terminal after the base terminal voltage becomes "H".
Q301 LOCAL SEEK SW Changes to the local seeking after the base terminal voltage becomes "H".
Q501 MOTOR DRIVER AVR Works when the base terminal voltage becomes "H". Supplies the power to the motor driver.
Q551 MAIN MOTOR SW Works when the base terminal voltage becomes "L".
Q552 MAIN MOTOR SW Works when the base terminal voltage becomes "H".
IC1 LCD DRIVER
IC2 REMOTE SENSOR
Q1 KEY SCAN SW Receives key signal when the base terminal voltage becomes "L".
Q2 KEY ILLUMINATION SW Key illumination color becomes green when the base terminal voltage becomes "H".
Q3 KEY ILLUMINATION SW Key illumination color becomes red when the base terminal voltage becomes "H".
● SWITCH UNIT (X16-1532-71)
Ref.No. Function Operation
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KRC-4902Y
4
● µ-COM (IC1 : X14-)
Pin No.
Pin name I/O Description
Processing Operation
1 DSI O DSI control.
2 PANEL I Panel detection. "L": Panel exists.
3- -4 AVSS - GND.
5 L-RST O LCD driver reset.
6 L-CE O LCD driver chip enable.
7 AVREF1 I Reference voltage
8- --
9 PLL-DATA I/O Front-end communication data.
10 PLL-CLK O Front-end communication clock.
11 L-DATA L I LCD driver communication data.
12 L-DATA S O LCD driver communication data.
13 L-CLK O LCD driver communication clock.
14 R-DATA I RDS data.
15 R-QUAL I RDS QUAL.
16 CH-DATA C I Changer communication data.
17 CH-DATA H O Changer communication data.
18 CH-CLK I/O Changer communication clock.
19 M-STBY I Cassette tape stand-by detection. "H": Stand-by.
20 T-END I Tape end detection. "H": Run. "L": Stop.
21 ACC-DET I ACC detection.
22 BU-DET I Back-up detection.
23 IC2 TYPE 0 I For service. "L": Normally.
24 IC2 TYPE 1 I For service. "L": Normally.
25 TYPE 0 I Destination discrimination.
26 TYPE 1 I Destination discrimination.
27 TYPE REF O
Reference voltage for destination and service.
28 MOTOR O Cassette mechanism motor. "H": ON. "L": OFF.
29 PLL-CE O Front-end communication chip enable.
30 SD I Station detection. "H": Station exists. "L": Station does not exist.
31 ASF O Noise detection time constant switch.
32 LO/DX O Local seeking switch. "H": LO. "L": DX.
33 VSS1 - GND.
34 P-MUTE O Power amplifier muting.
35 SVR O SVR control.
36 - - 37 IC2-SCL O E-volume communication clock.
38 IC2-SDA I/O E-volume communication data.
39 MUTE O Muting control.
40 P-STBY O Power amplifier stand-by.
41 P.CON-DET I P.CON short-circuited detection.
42 CH-CONT O Changer control.
43 - - 44 CH-REC H O Changer request.
45-47 - - -
48 EN2-1 O Power supply IC control.
MICROCOMPUTER'S TERMINAL DESCRIPTION
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5
KRC-4902Y
Pin No.
Pin name I/O Description
Processing Operation
49 EN2-0 O Power supply IC control.
50 BEEP O Buzzer.
51 EN3 O Power supply IC control.
52 EN1 O Power supply IC control.
53 SW 5V O P.ON 5V control. "H": OFF. "L": ON.
54 MUSIC I Tape signal detection. "H": Signal does not exist. "L": Signal exist.
55 MS-CONT O Tape advanced sensitivity control. "H": Play. "L": FF/REW.
56 EQ-MUTE O Cassette tape muting. "H": ON. "L": OFF.
57 FWD/REV I Cassette tape running direction detection. "H": FWD "L": REV.
58 SUB+ O Sub motor control.
59 SUB- O Sub motor control.
60 RESET I System reset.
61 REMOTE I Remote control.
62 R-CLK I RDS clock.
63 CH-REQ C I Changer request.
64 PACK-IN I Cassette tape pack-in detection.
65 KEY-REQ I Key signal detection.
66 - - 67 VSS0 - GND.
68 VDD1 - VDD.
69 X2 - Main system clock.
70 X1 I Main system clock.
71 IC - 72 - - 73 XT1 - VDD.
74 VDD0 - VDD.
75 AVREF 0 I Reference voltage.
76 S-METER I SD detection. "H": SD exists. "L": SD does not exist.
77 T-MODE I Cassette tape mode detection.
78 PHONE I
Navi mute: Over 2.5V. Tel mute: less than 2.5V.
79 NOISE I Noise detection during FM mode.
80 AV CONT O Reference voltage.
MICROCOMPUTER'S TERMINAL DESCRIPTION
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FIG.
6
KRC-4902Y
TEST MODE / ADJUSTMENT
1. How to enter the test mode
• Reset the unit while holding the "FM" key and preset "6"
key.
• All indication segments go ON at the beginning of the test
mode.
2. How to release the test mode
• Simply reset the unit.
• (NOTE) The test mode should not released in conditions of
ACC OFF, power OFF, momentary power down or the
panel off.
3. Test mode
• Blanking Skip (B.S) OFF.
• Eject a tape by pressing "ATT" key.
4. Audio adjustment
• Enter the audio mode by pressing the "AUD" key or
"OPEN/CLOSE" key on the remote controller.
• Set the volume level to be -10dB. In that case, "30" should
be shown on the display.
• Loudness OFF.
• The BASS/MIDDLE/TREBLE and BALANCE/FADER can
be adjusted to the full-boost/full-cut and full-front/ full-rear
each by pressing the "UP" and "DOWN" keys.
5. Menu mode
• Enter the menu mode by pressing "CLK" key or "DNPP"
key on the remote controller.
• Only on models with RDS function, Local Seeking should
be first menu.
BALANCE/FADER/BASS/TREBLE : CENTER
T.ADV/METAL/DOLBY NR/AUTO : OFF
TEST MODE
ADJUSTMENT
ITEM
INPUT
SETTINGS
OUTPUT
SETTINGS
RECIEVER
SETTINGS
ALIGNMENT
POINTS
No.
AZIMUTH
TCC-153
10kHz
SP OUT TAPE PLAY
Head azimuth
screw
(FWD/REV)
(ME1)
ALIGN FOR
Adjust so that output level in
playing "FWD"and "REV"
becomes maximum each.
(b)1
CASSETTE DECK SECTION
(b) AZIMUTH
FWD
REV
PANEL FRONT