Kenwood KR-C765 Service Manual
CASSETTE RECEIVER
KRC-765
KRC-691/691Y
SERVICE MANUAL
● KRC-691
© 2001-12 PRINTED IN JAPAN
B51-7878-00 (S) 2177
MECHANISM EXTENSION CORD
W05-0477-00 (7P)
W05-0609-00 (10P)
Knob(VOL)
(K25-1414-03)
OFF
SRC
LOUD
Knob(ATT)
(K25-1411-03)
∗ Refer to the PARTS LIST
DC cord
(E30-4940-05)
Knob(SRC)
(K25-1410-03)
DAB
Knob(FM,AM)
(K25-1412-03)
KRC-691
PROG/PTY
MENU
DOLBY B NR
AUD
DC cord
(E30-4944-05)
∗ Panel assy
(A64-2614-02)
SCAN B.S/RDM REP MTL/M.RDMB NR NAMEDISP TI
Knob(1-6)
(K25-1409-03)
Plastic cabinet assy
(A02-1486-13)
∗ Front glass
(B10-4192-01)
47Wx4
Mounting hardware assy
(J21-9716-03)
Lever
(D10-4589-04)
Remote controller assy
RC-410 (A70-2025-05)
: KRC-765 only
Screw set
(N99-1719-05)
: KRC-765 only
Screw set
(N99-1656-05)
Escutcheon
(B07-3055-05)
KRC-765/691/691Y
BLOCK DIAGRAM
ANT.
AUDIO
HEAD L
T-END
STBY
F/R
MODE
SUB+
SUB-
MOT+B
REQ H
REQ C
DATA H
SW 5V
Q52
FM+B
Q54
AM+B
DOLBY EQ
MS OUT
NR SW
MUTE SW
TAPE SW
MS MODE
IC9
SW 5V
A 8V
S1
PANEL
DET
Q55
BUFFER
IC7
RDS
DECODER
3
2
5
5
8
SW 5V
IC1
RCLK
QUAL
RDATA
S METER
IFC
PLL DATA
PLL CLK
MUSIC
DOLBY
EQ-MUTE
METAL
MS CONT
T-END
M-STBY
F/R
PACK IN
T-MODE
CH CLK
REQ H
REQ C
DATA C
DATA H
CH CON
CH RST
CH MUTE
EJECT ILL
DSI
EJECT
KEY
PANEL-DET
EJECT-ILL/DSI
AM+B
EJECT
AM : 230mV
AFS
FM+B
B.U. 5V
MATRIX
388mV
1200mV
BUFFER
Q44
NOISE
SUB+
SUB-
KEY
ED1
2
IC8
RESET
RESET
TUNER
S-METER
IFC OUT
PLL DATA
PLL CLK
CASSETTE
MECHA
HEAD R
HEAD COM
PACK IN
MODE+B
CD-CHANGER
MD-CHANGER
CH CLK
DATA C
CH CON
CH RST
CH MUTE
BACK UP
FM :
460mV (K TYPE)
251mV (E TYPE)
IC2
FM
AM
TAPE
CHANGER
S METER
AFS
QUAL
SYSTEM u-COM
RESET
L DATAS
L CLK
DIM CON
L CE
6
SW
IC1
LCD
DRIVER
LCD
E-VOL
N.C.
MPX
SDA
SCK
L DATAL
L-CLK
REMO
IC2
2
S MUTE
SDA
REMO
IC10
SUB MOT
A 8V
SCK
SUB +
2
DRIVER
MOT+B
(X16- )
G/R SW
Q3,4
PRE MUTE
P MUTE
DIMMER
ACC DET
ANT CONT
B.U DET
SUB -
MAIN MOT
AVR
MUTE
BEEP
PHONE
P CON
P-5V
P ON
MOTOR
Q18,19
ILL ON
IC3
MUTE LOGIC
B.U. 5V
TH1
THERMO
PROTECT
Q31
DIMMER
TEL MUTE
Q39
ACC DET
Q32,33
ANT CON
P CON
Q38
B.U DET
PAN 5V
Q61
Q13
SW5V
SW 5V
Q23
ILL AVR
SW 5V
Q34-36
B.U. 5V
B.U. 5V
Q1-4
MUTE
DRIVER
A 8V
Q72
VOLTAGE
LIMITTER
FM
AM
CH
BACK UP
IC4
POWER IC
MUTE
Q11,12
B.U.5VP-5V
Q16,17
A 8V
SW14V
SW 5V
E TYPE K TYPE
1800mVTAPE
1372mV
855mV
3600mV
AUX IN
Q14,15
1800mV
1800mV
600mV
3600mV
1.8V
PRE OUT
SP OUT
DIMMER
TEL MUTE
ACC
ANT CON
P CON
WIRED
REMO
BACK UP
2
KRC-765/691/691Y
COMPONENT DESCRIPTION
● SYNTHESIZER UNIT (X14-68XX-XX)
Component
IC1 SYSTEM µ-COM
IC2 E-VOL, N.C. NPX
IC3 Mute logic circuit 4 input NOR gate x 4
IC4 Power IC
IC7 RDS Decoder
IC8 Reset IC "L" detection voltage: 3.0 V or less
IC9 Equalizer amplifier DOLBY B
IC10 Sub motor driver
IC11 EEPROM
Q1 Audio mute SW Front L-channel is muted when base goes "H".
Q2 Audio mute SW Front R-channel is muted when base goes "H".
Q3 Audio mute SW Rear L-channel is muted when base goes "H".
Q4 Audio mute SW Rear R-channel is muted when base goes "H".
Q11,Q12
Q13 SW 5V ON when base goes "L".
Q14,Q15
Q16,Q17
Q18,Q19
Q20,Q21
Q23 ILL AVR Inverted darlington connection
Q31 Dimmer control SW Small light detection when base goes "H".
Q32,Q33
Q34,Q37
Q35,Q36
Q38 B.U detection
Q39 ACC detection "L" when ACC is present.
Q42 Mute driver
Q43 MUTE SW for E-VOL. Turns on when base goes "L" and E-VOL is muted.
Q44 Noise buffer
Q51,Q52
Q53,Q54
Q55 Composite signal buffer
Q61 PANEL 5V SW ON when the base goes "L".
Q71 MSTC SW ON when the base goes "H".
Q72 Sub motor AVR 7.3V output when AUDIO 8V is turned on.
Q82 EJECT ILL/DSI SW ON when the base goes "L".
Purpose • Function Operation • Conditions • Compatibility
B.U. 5V AVR Darlington connection
SW 14V
AUDIO 8V AVR Darlington connection
Main motor SW Q19 is turnd ON when Q18's base goes "H".
ILL power ON/OFF SW Q21 is turnd ON when Q20's base goes "H".
Power antenna SW Q33 is turnd ON when Q32's base goes "H".
Power control SW Q34 is turnd ON when Q37's base goes "H".
Power control circuit
output protection
FM+B SW Q52 is turnd ON when Q51s base goes "H".
AM+B SW Q54 is turnd ON when Q53s base goes "H".
Audio 8V ON/OFF SW
Q15 is turnd ON when Q14's base goes "H".
When the output voltage decrease is detected, Q37 is turned off to protect the output.
When the power control switch is turned on, Q35 protects the system from
misoperation.
"L" when B.U is present.
"H" when B.U is absent or when momentary power down detction.
For driving the audio mute switch.
ON when the base goes "L".
● SWITCH UNIT (X16-16XX-XX)
REF.No. FUNCTION OPERATION
IC1 LCD driver
IC2 Remocon IC
Q1 Key scan start SW ON when the base goes "L".
Q3 Key illumination SW (RED) ON (Key Illmination Red) when the base goes "H".
Q4 Key illumination SW (GREEN) ON (Key Illmination Green) when the base goes "H".
Q5,D26 VLCD AVR AVR, ON when the base goes "9.1V".
Q6 Remocon IC VDD suply SW Supply of Remocon IC VDD when the base goes "H".
Q7 Dimmer control LCD Back Light Control (PWM Control)
3
KRC-765/691/691Y
MICROCOMPUTER'S TERMINAL DESCRIPTION
● IC1(SYNTHESIZE UNIT : X14-68XX-XX)
Pin No.
Pin Name I/O Description Processing Operation
1 TYPE 1 I Destination type selection port
2 TYPE 2 I Destination type selection port
3 IFC I F/E IFC OUT input terminal H: Station exists Vth: 2.5V
4 AVSS - A/D,D/A converter ground connection terminal Connected to GND lines.
5 IC2-TYPE 1 I Maket/genuine select (Noise cancel) L: Maket H: genuine
6 PANEL-DET I Panel detection L: Panel exists H: Panel does not exists
7 AVREF1 I D/A converter reference voltage input terminal Connecting to BU5V
8 CH-DATAC I Data input from changers
9 CH-DATAH O Data output to changers Last maintenace
10 CH-CLK I/O Clock input/output with changers input
11 L-DATAL I Data input from the LCD driver IC Communication speed 600kHz (max)
12 L-DATAS O Data output to the LCD driver IC
13 L-CLK O Clock output to the LCD driver IC L: Panel detachd
14 L-CE O LCD driver chip enable H: Driver select L: Not select
15 BEEP O BEEP sound output
16 PLL-DATA I/O Tuner (01ST) data input/output Last maintenace
17 FLIP-DET I Panel detach detection L: Panel attached H: Panel detached
18 PLL CLK O Tuner (01ST) clock input/output
19 N.C. O Not used
20
EJECT ILL/DSI
21 L-RST O Reset output to the LCD driver IC L: Reset ON H: Reset OFF
22 PAN 5V I/O Panel 5V control terminal
23 R-DATA I Data input from the RDS decoder IC
24 R-QUAL I Quality input from the RDS decoder IC
25 SUB (-) O Sub motor output (-)
26 SUB (+) O Sub motor output (+)
27 FWD/rev I Cassette tape running direction detection H: FWD L: REV
28 MS-CONT O ADV sensitivity control H: PLAY L: FF/REV
29 metal O NORMAL/METAL change H: NORMAL L: METAL
30 EQ-MUTE O EQ-MUTE change H: ON L: OFF
31 DOLBY O Dolby ON/OFF H: ON L: OFF
32 music I Casstet music space detection H: Music does not exists L: Music exist
33 VSS1 - GND
34 IC2 TYPE 0 I Maket/genuine select 0 (ROLL-OFF) L: Market L: Genuine 0
35 AM+B O AM power supply terminal H: During AM reception
36 FM+B O FM power supply terminal H: During FM reception if with RDS
37 AFS O Noise detection time constant switching terminal
38 IC2-CLK O IC2 clock output
39 IC2-DATA I/O IC2 data input/output
40
EEPROM DET
41
P-MUTE O Power IC mute control output
42 P-STBY O Power IC standby control output
43 MUTE O IC2 mute control output H: Mute ON L: Mute OFF
44 PRE MUTE O Pre-out mute control L: Momentary power down, Reset
DIMMER-CON
45
46 BU-DET I Momentary power down detection input
47 ACC-DET I ACC detection input L: ACC ON H: ACC OFF
48 dimmer I Small lights detection input L: ON H: OFF
49 REMO I Data input from the remote control light sensor
50 ANT-CON O Antenna control output H: TUNER, TI
O EJECT ILL KEY & DSI output L: Light ON H: Light OFF
I EEPROM detection terminal H: EEPROM exist L: EEPROM does not exists
O Dimmer Control
Communication speed 1.2MHz (max)
L: Panel detached
L: ON (Panel exists & ACC ON)
H: OFF (Panel does not exists or ACC OFF)
Hi: During FM reception, Lo: During FM seek or
AF search
H: Mute OFF
L: Mute ON, PowerOFF, All OFF, TEL Mute
L: Power IC OFF, All OFF mode
H: Power IC ON
Control with pulse output H: Power ON
L: Power OFF
H :BU OFF
L : BU ON
4
KRC-765/691/691Y
MICROCOMPUTER'S TERMINAL DESCRIPTION
Pin No.
Pin Name I/O Description Processing Operation
51 P-CON O Power control output H: Power ON L: Power OFF
52 CH-RECH O Request output to changers L: Request
53 CH-RST O Reset output to changers L: Normally
54 CH-MUTE I Mute request from changers H: ON L: OFF
55 CH-CON O Changer control H: ON L: OFF
56 P-ON I/O SW 5V control output H: OFF L: ON
57 MOTOR O Main motor output H: ON L: OFF
58 M-STBY I Cassette standby detection H: STBY
59
T-END
60 reset I Reset input terminal L: System reset H: Normally
61 eject I Eject key detection H: OFF L: ON
62 CH-REQC I Request input from changers H: OFF L: ON
63 ILL ON O Illumination output terminal H: ON L: OFF
89 KEY-REQ I Panel key interrupt input L: Key input exist
65 R-CLK I Clock input from the RDS decoder IC
66 PACK-IN I Cassette pack-in detection H: Pack-in
67 VSS0 - GND (port)
68 VDD1 - Positive power supply
69 X2 - Main clock output (12MHz)
70 X1 I Main clock input
71 TEST I Program power supply (Mask: Test terminal)
72 XT2 - Sub clock output (32.768MHz)
73 XT1 I Sub clock input
74 VDD0 - Positive power supply (port)
75 AVDD I A/D port reference voltage input
76 PHONE I Phone detection terminal
77 T-MODE I Tape mode detection Vth=2.5V
78 S-METTER I S-meter input from F/E
79 NOISE I FM noise detection input
80 TYPE 0 I Destination type selection terminal
I Tape end detection H: Tape play L: Tape end
Less than 1V: TEL mute
More than 2.5V: NAVI mute
5
KRC-765/691/691Y
TEST MODE
1. How to enter the test mode
• Reset the unit while holding preset 1 key and preset 3
key.
2. How to exit from the test mode
• RESET
• POWER OFF
• ACC OFF
• Bu OFF
• Panel detach
3. Initial status in test mode
• Sources : ALL OFF
• Display : All segments are lit.
• Volume : -10 dB (displayed as 30)
• LOUD : OFF
• CRSC : OFF regardless of the presence of
switching function.
• SYSTEM Q : Flat
• BEEP : ON
• DEMO : OFF
4. Special display during Tuner mode
If the following display appears during the TUNER mode,
the front end is defective.
• "TNE2P NG": EEPROM remains in the initial value (don't
care) because the product is shipped without passing the
F/E adjustment process.
• "TNCON NG": Communication with the F/E is not
possible.
5. Forced switching of K3I
Every pressing of the Preset 6 key during the TUNER mode,
changes the status from Forced middle → Forced narrow
→ AUTO → Forced wide → Forced middle.
When the product is set to the Forced middle: FMM in the
initial state, the following message appears.
• Forced middle : FMM
• Forced narrow : FMN
• AUTO : FMA
• Forced wide : FMM
• Track jump takes place to the following track when the
Track up key is pressed.
No. 9 → No. 15 → No. 10 → No. 11 → No. 12 → No. 13
→ No. 14 → No. 9 (The cycle restarts from here.)
• When the Track down key is pressed, track returns back
by one track during playback.
7. Audio system
• The product enters the audio adjustment mode when the
Q key is pressed momentarily.
• Continuous advance operation from remote control is
prohibited.
• The Bass/Middle/Treble is adjusted to either one of the 3
steps of MIN/Center/MAX with Track up/down key.
• Balance is adjusted to either one of the 3 steps of Left
MAX/Center/Right MAX with Track up/down key.
• Fader is adjusted to either one of the 3 steps of Rear
MAX/Center/Front MAX with Track up/down key.
• HPF (high-pass filer) is adjusted to either Through or 220
Hz with Track up/down key.
• LPF (low-pass filer) is adjusted to either Through or 120
Hz with Track up/down key.
• Bass f/Bass Q/Bass EXT/Middle f/Middle Q/Trable f do
not appear on the audio adjustment.
8. MENU system
• The product enters the MENU mode when the CLK key
is pressed momentarily.
• The product enters the MENU mode when the DNPP/
SBF key of the remote control is pressed.
• Continuous advance operation from remote control is
prohibited.
• The calendar adjustment, calendar display switching and
calendar memo are deleted from the advance operation.
(FL model)
• Red is set by the preset 1, blue by 2, green by 3 and
white by 4 in the color adjustment mode. (VCLD model)
• Contrast can be adjusted in 3 steps of 0/5/10. Initial value
is 5. (VCLD/VCLD model)
• Brightness can be adjusted in 3 steps of 0/5/10. Initial
value is 10. (Normal FL model)
6. Test mode specifications of the CD receiver
• Forced eject operation is prohibited during the reset start
mode. CD cannot be recognized when the product is reset
with CD remains inserted.
6
9. Backup current measurement
If RESET is activated in the ACC OFF state (when BACKUP
button is turned ON), the MUTE terminal turns OFF in 2
seconds, not in 15 seconds. (At this time, the panel/CD/
TAPE mechanism does not operate.)
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