Kenwood KRC-851D User manual

STEREO
CASSETTE
RECEIVER
|
KE
NWOOD
KRC-851D
SERVICE MANUAL
©1990-2 PRINTED IN JAPAN
B51-6133-00(B)1602
Knob (TONE)
(K23-1004-04)
Panel assy
(A20-7551-03)
Escutcheon assy
(BO7-2014-12)
Knob (VOL)
(K29-5538-03)
Metallic cabinet
(AQ1-2508-21)
Detachble connector
(WO09-0715-04)

KRCO-851D
CONTENTS
TROUBLESHOOTING GUIDE.................0...... 2 PC. BOARD .iscscee noe tad eek ie ied vee Dae eek 31
CONNECTIONS ...........0.0 0200 e cece eee eee eee 3 SCHEMATIC DIAGRAM................-..000022005 39
DISASSEMBLY FOR REPAIR..................2.-.. 4 EXPLODED VIEW (MECHANISM).................. 49
BLOCK LEVEL DIAGRAM ..................00200 008 5 EXPLODED VIEW (UNIT) .....................00.00, 50
CIRCUIT DESCRIPTION .....................00 2s 6 PARTS HS 1-3. occcd.at ieahesienave sive cee gees 51
MECHANISM DESCRIPTION ..................-.0.. 20 SPECIFICATIONS ...................065 BACK COVER
ADJUSTMENT ......... 000s cece eee e eee ees 26
TROUBLE SHOOTING.................0....2.2 000. 28
TROUBLESHOOTING GUIDE
Other than the previous, this unit displays various error indications to show the
following messages.
E-0OO : CD-changer control output is not connected.
E-—0O1 :No disc magazine in the changer, or the magazine is not set completely.
E - 02 : No.discs in the disc magazine.
E-0O3 : The specified track is not present on the disc.
(Example : This appears when the 15th track is specified for a disc on
which only 10 tracks are contained.)
E— 04 : Disc is too dirty.
Condensation has occurred on the disc, or water drops are on the disc.
Disc is set upside down.
E-—0O5:Memory play switch is pressed with no memory.
E —- 99 : Operation incorrect due to something being defective.
Press the Reset button on the unit.
If the “E-99” indication does not disappear with this operation, consult
your nearest KENWOOD Service Agent.
E-OD: @When the temperature exceeds 60°C, the protection circuit is engaged
to stop any operation. At this time , this indication will appear.
@Open a window or tunn the air — conditioner ON to lower the
temperature. After a while, this indication will go out.
@This indication also appears for several seconds when making
connections, or when the Reset button is pressed.
E-OE: This is displayed when the condition of “E-OD” is released.
load: This indication appears while a disc is being changed inside the changer.
CAUTION : Memory play, Random play, Track repeat or Track scan cannot
be initiated while the load indication is displayed.
* When no indicator appears in this unit and only illumination appears, the cable
connector may nearly be disconnected.

KRC-851D
CONNECTIONS
@ Detachable case
p= [ | To FM/AM antenna
til
IN
et
:
(O>
CT
inout
es
tpt
i
Power
amplifier
Rear
(optional)
speakers
Front
(7)
=>]
dinput
ouput
.
Power
amplifier
se
(optional)
speakers
Ignition
key
switch
Power supply
UD lead (Red) ®
{_} abe (To ignition)
eI Memory backup lead (Yellow)
{_} ® (To battery) = i i
Ground lead (Black) © (To car chassis) =s
Power control supply lead (Blue/White) Battery
(Full automatic Power antenna control lead)
Automatic illumination/Dimmer control
supply lead (Orenge/ White)
(To light control switch)
‘Phone interface lead (Gray)
Connect to the plus © or minus © terminal CAUTION
of the telephone speaker or buzzer, or to the
head phone jack or speaker terminals.)
+ Even with two speaker system,connect the
speakers to each connecting cord, but avoid
the connections as shown below.
ipe)
<=] © Front left
Ss speaker
(White stripe
[REAR
t
)
ee
Rear
left
a5]
O
speaker
(Gray
stripe,
®
[FRONT
-
8)
Fron
ia
crane
the
(Purple stripa
oS] 4
Re 1 © Rear right
iS) speaker
a
5
(Green str
CD — Changer
control
output
Output
Control box unit
(Provided with
the KENWOOD
CD — Changer )
KENWOOD CD — Changer
(Option)
(En) 33

KRC-851D
DISASSEMBLY
FOR
REPAIR
Replacing
the
motor
(1)
Replacing
the
pinch
roller
1.
Disconnect
the
flexible
cord...
1)
6.
Detach
the
spring...
6}
2.
Remove
the
two
screws
@
and
disconnect
the
7.
Remove
the
two
screws
@
and
detach
the
sub
chas-
board.
sis.
3.
Take
out
the
washer
@
and
detach
the
loading
arm.
8.
Detach
the
pinch
rollers
individually
...
3]
Replacing
the
sub
motor
(2)
Replacing
the
Playback
head
4.
Take
out
the
washer
€}
and
detach
the
door
arm
9.
Remove
the
two
screws
@
and
detach
the
head.
plate.
5. Remove the two screws @ and detach the motor
assy.

KRC-851D
BLOCK LEVEL DIAGRAM
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KRC-851D
CIRCUIT DESCRIPTION
SYNTHESIZER UNIT (X14-285)
Use and Function Operation and Condition
TAPE EQ amplifier
| DOLBY B/C type
1/2Vec buffer
| Power amplifier BTL Output
PLL ~ For Synthesizer Tuning
| CO-CH interface Data Buffer
8,9 | Voltage detection SV for I1C12
10 T.ADV a ' Between-tunes Detection
11 Mecha. sub moter driver
12 4 Microprocessor | Key input,PLL,LCD control
14 i AVR _ | Veo for audio,tuner
15 ACC detection ‘ For muting
Q1,2 | E€Q mute
Q3-6 | Audio mute _
Q7,8 ' LOUDNESS SW
Q9,10 | VOL.boost SW
Q11,12 Buffer ets Power amplifier input
Lo/Dx SW For AM
Q14 LPF ee For PLL
Q15,16 TUNER +B SW 7 | Q1S:FM Q16:AM
Q17 / AM BS driver
Q18 | AM AGC cut SW For AM
Q19 | SK tamp inhibit SW
Q20 | ST IND. driver
Q2) FM MUTE inverter i SEEK STOP signal
Q22,23 ; SD signal inverter | SEEK STOP signal
VCC SW for PLL LPF
Q25-28 | P-CONT.
Q31 [ DIMMER inverter
DK/RST out inverter
RST in inverter
Q34 | CD-CH DATA inhibit
| Q34,36 driver
CLK inhibit
Q37 CD-CH CONT buffer
Q38 | CD-CH REQ buffer
Q39 RESET
Q40 ; POWER ON SV SW
Q41 POWER ON SW | Active LOW
Q42,43 j; 9.6V AVR
Q44-46 | T-ADV SENS. SW ie.
Q47,48 j_AVR for SUB MOTOR _ | 10V(Kick:14v)
Q49 i KICK SW i
Q50,51 | MANUAL RESET 4
Q52,53 SK/VALET,DK SW ‘ Key matrix control
Q54,55 | DINMER SW Se
T
|
+—
|
:
+
|
|
|

KRC-851D
CIRCUIT DESCRIPTION
SYNTHESIZER UNIT (X14-285)
Use
and
Function
Operation
and
Condition
Q56-59
|
ILLUM
SW
Amber/Green
Q60,61
AVR
control
Q62
,63
AVR
for
lamp
Q64,65
|
MAIN
MOTOR
SW
ago
|
Acc
SW
|
POWER
ON
Q81
7.5V
AVR
SW
Q82
7.5V¥
AVR
=<
Q83 _|_ LOUD SW driver
Q84 _i Ripple filter
Q85 j VOL. boost SW driver
Q86 ,87 Audio mute driver
Q88 ,89 | DOLBY NR control
Q90-92 | ACC detection
iC] ‘ FRONT PREAMP
{C2 i REAR PREAMP
{c3 : Analog SW *
1C4 __tsolation amp _
{c5-7 ‘a Buffer amp
Signal selection
EXT.MUTE SW
|
FM IF amp/ DET.
FM MPX / NC
SOK ;
| Buffer amp
RESET
FM IF amp —
$0 buffer
| MPX buffer
cRSC SW
AFC SW

KRC-851D
CIRCUIT DESCRIPTION
7.5 V AVR
1C14: M5237L is the AVR IC exclusive for driver and
used in combination with the PNP transistor.
When the power is turned ON, 041 turns ON to pull
the base of Q81 to turn 081 ON.
When O81 turns ON, IC14 pulls the base of Q82
through R292.
The collector output voltage of Q82 is divided by
R292 and R293, then fed back to IC14.
IC14 compares the above voltage with the internal
reference voltage and controls the base voltage of
Q82 so that the returned voltage coincides with the
reference voltage.
C142 makes the rising edge of VCC when the power
is turned ON become gentle.
ACC Detection Circuit
IC15: PST529D-MT is used for power voltage surveilance.
ACC voltage is divided by R306 and R308, and
voltage-limited by D42, then applied to terminal |
(input) of IC15.
When the input voltage (terminal |) is dropped below
threshold voltage (approx, 8 V, when converting to
ACC voltage) of C15, terminal O (NPN, open collector)
turns ON (= low).
When terminal O if IC5 is inverted to low, the emitter
of Q90 goes low and Q91 turns OFF, then Q92 turns
OFF.
Therefore, 1C12 pin (33): ACC | which is pulled down
by R310 goes low. That is, it is judged as ACC voitage
is at low level.
At the same time, IC4, 5 pin (4) STBY (standby) pin is
inverted to low via D44, and turns PWR (power) IC
OFF, while the base of Q86 is pulled so that Audio
Muting (MUTE) is activated.
When the ACC voltage raises and the terminal | of
IC15 exceeds the threshold voltage, the operation will
be reversed and it is judged as the ACC voltage is at
high level, while the PWR (power) IC is turned ON
and Audio Mute is released.
(However, since Audio Mute is ORed with IC12 pin
(23) MUTE, audio muting will not be released immedi-
ately because of the latter MUTE, even if the above
operation releases the MUTE)
vce BACK UP +8
POWER ON
(LOW?)
GND
Vref: Internal reference voltage = 1.26 V
R309
1c 12@) Pwr
1c4,5
MUTE
Bu SV
ACC
+8
1ci2
ACCIN

CIRCUIT DESCRIPTION
VREF Buffer
IC2: CXA1332M works using the voltage which is the
half of VCC (1/2 VCC) applied to pin (17): VCTO as a
reference. That is, the 1/2 VCC is used as the signal
ground.
In this unit, since all the power supply works with a
single power, the above 1/2 VCC (VCTO) is buffered by
the voltage follower op-amp IC3 so as to supply the
power to each block.
Pin (1) output supplies 1/2 VCC to the following:
CD-CH isolated amp
AUX isolated amp
Analog switch buffer amp
Tone amp
Pin (2) output supplies 1/2 VCC to the following:
Pre-amp
Power amp input buffer
AC GND of power amp negative feedback
Main in isolated amp
Manual RST (Reset) Circuit
When the voltage at pin (7) is inverted to high, IC12 is
initialized if pin (28) is at high level.
When the voltage at pin (7) is inverted to low, IC12
stops its function, and interrupts each power circuit and
this causes shock noise.
Therefore, Audio Mute is activated by the collector
output of Q51, while 1C12 pin (7) is controlled with a
slight delay determined by the time constant of R189
and C129.
The Voltage charged in C128 is applied to 1C12 pin (28)
via D28 and R188, but the reverse current is inhibited by
D28 even when the collector of 051 goes low (Q51
turns OFF), while since discharging is done with a gentle
time constant consisting of R187 and C128, the high
level is kept for a while.
BU 5V
1¢12(7)
1cl2
sw
asi
COLLECTOR
aso
BASE
— 250
1e@= COLLECTOR
1c 12 @8)
MUTE
KRC-851D
1c 2 (7) veto
c3
TO +8(7.5V)
RST( RESET) SIGNAL
FOR CO-OH. AND
AUDIO MUTE.
028
TCl2 PIN(23) MUTE

KRC-851D
CIRCUIT DESCRIPTION
Description of EXT-MUTE
With the power ON, when the EXT-MUTE signal is ap-
plied (the signal is inverted from high to low), the
“CALL” indication appears on the 7-segment display
then, the unit enters the all-off status.
When any of the TUNER, CD or TAPE key or the MODE
key on the remote control is pressed, or when the power
of the unit connected to the PACK IN or PREOUT termi-
nals is turned ON, the corresponding function starts play-
back regardiess of whether or not the signal is turned
ON.
When the ACC is turned ON while the “CALL” indication
appears, the unit enters the Last Tuner mode.
*While 2 seconds after the EXT-MUTE signal is
sensed, any key will not be accepted.
@ EXT-MUTE during DK interruption:
The EXT-MUTE function will have priority even during
DK interruption.
@ EXT-MUTE during playing of the unit connected to
PREOUT:
If the unit connected to the PREOUT terminals is
being played, the P-CON is turned ON while 2
seconds, or until the RESET-IN is turned OFF, to reset
the subsequent unit.
If the RESET-IN is turned ON within 2 seconds after
the EXT-MUTE is sensed, the P-CON is turned ON 200
msec later so as not to turn ON the subsequent unit.
If the RESET-IN is still ON even when 2 seconds after
the EXT-MUTE is sensed, the display is changed from
“CALL” to “DA” then the previous mode of the subse-
quent unit will resume.
@ EXT-MUTE during audio adjustment:
When the EXT-MUTE is turned ON during adjusting
the BASS, TREBLE, BALANCE or FADER, the adjust-
ment mode is changed to volume adjustment mode
automatically, then the rotary encoder signals will not
be accepted for 2 seconds.
@ EXT-MUTE during inputting the VALET CODE:
During registration of the code:
The entered code will be cleared and the VALET
CODE registration mode will be released.
During inputting the VALET code to release the
VALET mode:
The EXT-MUTE signa! will be ignored.
10

KRC-851D
CIRCUIT DESCRIPTION
Operation Description: EXT. MUTE
(1)
(2)
Connections:
The “MUTE IN1” and “MUTE IN2” are connected to
the core wires (red and white) of the 2-conductor
shielded cable.
Connect these core wires to the speaker terminals of
the telephone set. (Shielding jacket should not be
connected to anywhere,)
Circuit Operation:
When there is a ringing on the speaker of the tele-
phone set, the ringing signal is applied to the buffer
of IC6 via the filter consisting of R93, R94, C91 —
C94, R38 and R39 and the protection diode consist-
ing of D1 and D2.
After passing through the buffer, due to the balanced
input signal path, the only difference components
between IN1 and IN2 will be amplified (in IC7). The
DC components are eliminated, and the AC level
signal is rectified by the rectifier circuit consisting of
D3, C25, R46 and R47 to convert into the DC level.
Then, the signal is inverted by Q3 and R234 to be
supplied to the port of the microcomputer. R49 and
C26 are used to set the time constant so as to delay
the response.
(xX08-2412-70)
03
IN PORT
| EXT. MUTE IN
{X14-2852-70)
Ic7 (2/2)
(3) Operation on the Unit:
When the microcomputer detects the EXT-MUTE
signal, the unit enters the all-off status while “CALL”
appears in the display.
To restore from the “CALL” status, press the PLAY
key of the source connected.
Tuner ............ TUNER/PWR key
Tapes evades. setene PLAY/PROG key
CD; CH s ieeies PLAY/PAUSE key
1C6(2/2)
7.5V | |
O
GND MUTE MUTE
IN2 INI
(X89-1142-70) |
{F/6)
11

KRC-851D
1012: 75116GF-616-3BE
KICK
POWER
DOLBY
B/C
P-CON OUT
RST OUT
RESET
x2
x1
RST IN
EXT MUTE IN
PAUSE
DATA IN
CLK
DATA OUT
CE
MOT
AUX1
AUX2
12
CIRCUIT DESCRIPTION
Microprocessor IC
MODD IN
EQ MUTE
F/R OUT
(2)<— PACK IN
‘oS
G)
@) @) ®)
@)
()
@)
©)
) ©) ©)
©)
KR1
KR2
KR3
KR4
KR5
KR6
KR7
STBY
CHEHEHODEKEKOE)
DATA OUT
(41)-<—— DATA IN
(40) CE DISP
G3) BVZ
(8) PCL
G7) INH OUT
(36) STELEO IN
(35)<-——— METAL IN
(34) MUSIC IN
G3) ACC IN
OOOOMOOOOOOOO OO MH IV OMADO)
(8)
©) ©) @) ©) @)
@)
)
©)
VSS
ILL IN
EXT - RST —+>@)
ILLG
ILLA
MUTE
CH-CON
REQ OUT
CD - CH REQ IN ——*()
REELT —*(2)
REELS —+(8)
STB/LOUD
REMOCON IN —— (8)

KRC-851D
CIRCUIT DESCRIPTION
Assignment
Function
KICK
“L” output when sub-motor of mechanism needs to be rotated strongly.
“H” output for normal rotation of sub-motor.
POWER
“H" output during power ON.
“H” output when reading the initial setting.
DOLBY
DOLBY IC NR control output.
“H” output for DOLBY B or C.
B/C
DOLBY IC NR control output.
“H” output for DOLBY C.
P-CON OUT
Output for P-CON.
“H” output when making the P-CON output “H”.
DK OUT/
RST OUT
For destination E: VOL boost or output DIN cable DK output.
Active “H”—-boost
—DK line—“L”
For destination J: AUX IN RST OUT output.
Active “H”-RST—“L”
Reset input port, Active “L”.
Initialize or standby mode cancel input.
X-tal OSC.
EXT MUTE MUTE __IN/
AUX P-CON IN
rf
DO Oo
(I)
CE ie}
(I)
MOT
Mutual operation input.
“H” input when RST is “L” in output DIN cable.
For destination E or K: EXT. MUTE input, Active “L”.
For destination J: AUX IN P-CON input, Active “L”.
Mechanism pause mode (standby mode) input pin.
At “H", the mode is judged to be the pause mode.
a pin of data from PLL.
PLL/E-VOL serial data control CLK output.
iM Input pin for initial setting.
1) PLL/E-VOL serial data control DATA output.
2) Input pin for initial setting.
1) PLL serial data control CE output.
2) Input pin for initial setting.
“H" when rotating main motor of mechanism.
AUX 1 “H” when listening to signal from AUX IN.
AUX 2
“H” when listening to signal from CD-CH.
ILLUM G
Illumination green output.
“H” output when turning on illumination in green.
ILLUM A
ilumination amber output.
“H” output when turning on illumination in amber (Initially in amber).
STB/LOUD 1) When electronic VOL initial setting is made...
Electronic VOL serial data control strobe signal output.
2) When analog VOL initial setting is made...
Loudness ON/OFF output “H”=ON.
MUTE
“L" output during mute.
CH-CON
“H” output when operating CD-CH.
REQ OUT
Output to request communication from master to CD-CH Active “H”.
ILLUMI IN
[llumination input port.
Even in the power OFF state, when “L” is input, the illumination output port
corresponding to the memorized color is made “H”. (ILLUM G — pin 20)
{ILLUM A — pin 21).
EXT - RST
External reset input, Active “H”.
Initialization when “H” with RST input.
CD- CH REQ IN
Input to request communication from CD-CH to master.
REMOCON IN
Remote control data input port.
13

KRC-851D
14
CIRCUIT DESCRIPTION
Assignment
Function
31
| PTHo3
Reel pulse input
(takeup)
Reel pulse input (takeup reel side in FWD).
Reel pulse input
(supply)
Reel pulse input (supply reel side in FWD).
ACC IN
When “H" is input, ACC “existence” is judged.
MUSIC IN
When “H” is input, tape tune “existence” is judged.
METAL IN
When “H” is input, LCD’s MTL display is lit.
STEREO IN
When “H” is input, LCD’s ST display is lit.
INH OUT
“H” output when turning on LCD display or “L” output when turning off.
Division
output
For destination Japan, only during ALL OFF mode, a 1/4 or 1/8 division of
4.19 MHz is output.
BUZ
Buzzer sound output port.
For buzzer sound, description is made separately.
40 [ P20
CE DISP
LCD Dr control STB output port.
DATA IN
Input port of data from CD-CH.
DATA OUT
LCD driver CD-CH control data output port.
CLK
Clock pulse I/O port.
LCD driver/CD-CH communication data clock.
Clock input port for CD-CH to master reception.
Standby mode detect input (momentary voltage decrease detect input), Active “L”.
After interrupt takes place, when the port is “L”, the standby mode is engaged,
while when “H”, the standby mode is canceled.
Key return signal input.
Active “L”.
Key source signal output.
Active “L”.
Connected to VDD.
F/R OUT
Tape equalizer amplifier FWD/REV select output.
“L": FWD, “H”: REV.
EQ MUTE
Tape equalizer mute output.
When sound from tape should not be emitted ...
(during FF/REW, direction, loading, eject, etc.)
“H”" output during TAPE.
PACK IN
Tape pack-in signal input.
Active “H” (pack-in at “H”).
62
4 P30
MODE IN
Pin to input mechanism mode, to which mode detect photointerruptor output is
connected.
SUB-MOTOR ®
“H” output for normal rotating of mechanism sub-motor (“H” during brake).
SUB-MOTOR ©
“H” output for reverse rotating of mechanism sub-motor (“H” during brake).

CIRCUIT DESCRIPTION
Key Matrix
KRCO-851D
KS 0 KS 2 KS 3
KR O VOL DOWN {E-VOL) R SK (D}
(for encoder)
KR 1 VOL: UP (E-VOL) R_ DK (D)
(for encoder)
1
KR 2 AUDIO SELECT (E-VOL) LOUD (pressed slight) R AUTO R LOCAL (pressed slight)
VOL, BAS, TRE ILLUM (pressed deep) {with rear SDK ON) R AUTO MEMORY
BAL, FAD SK SEEK UP {pressed deep}
(with rear SDK ON)
DISPLAY CHANGE
KR 3 R 3 R 4
T T-CALL T REPEAT
C REPEAT
KR 4 R R 7 R 8
T INDEX SCAN
C TRACK SCAN C DISC SCAN RANDOM C M. PLAY
R 9 0 DIRECT R TUNER ON/OFF
Cc
R
C (pressed slight)
C {pressed deep)
(pressed slight)
PWR OFF
(pressed deep)
AM FM
DISC SEARCH DOWN DISC SEARCH UP
DOWN TUNE UP TUNE
T NORM. REW T NORM. FF
{pressed deep) {pressed deep)
OPSS. REW DPSS. FF
(pressed slight)
C TRACK SEARCH DOWN
(pressed slight)
TRACK SEARCH UP
Notes:
1. As regards a key having a function only for a specific source (exclu-
sive keys) or a key of which the name and function vary with the
source (double and triple function keys), is before its name written
(R) (RADIO), (T) (TAPE) or (C) (CD-CH) as a source name.
Otherwise, of a key even without a number written, its name does
not vary with the source (single function keys).
2. As regards a key of which the name and function vary according to
the destination, is after its name written (D). (L). {(K) or (J) as a destina-
tion symbol.
3. Besides, supplementary explanation is made within (___).
SDK — (D)
P-SCAN — {L)
VALET — (K)
CLOCK — (J)
T STOP/EJECT
C PLAY/PAUSE
P-SCAN (K (C) unprovided)
SA (D, L, J (C) unprovided)
T PLAY/PROG
Alternate keys
Momentary keys
15

KRC-851D
16
Key Name
CIRCUIT DESCRIPTION
Function
e VOL DWN
@VOL UP
@ Electronic VOL volume, bass, treble, balance or fade control keys, which are subject to turning ON/OFF by rotary encoder (phase
output).
@ AUDIO SELECT
@ Electronic VOL control mode select key, which performs a mode selection in the order of volume, bass, treble, balance, then fade.
Note: For electronic VOL operation speed and timing, refer to a separate section.
SK
@ SK (=BK) signal existence/nonexistence input key {alternate key), which is effective only when destination D is selected (with SOK ON).
When the SK (=BK) signa! exists, this key is subject to turning ON.
DK
[ DK signa! existence/nonexistence input key (alternate key), which is effective only when destination D is selected.
When the DK signal exists, this key is subject to turning ON.
@ LOUD ILLUM
@ When pressed slight, this key serves as the loudness ON/OFF key (initially loudness ON).
@ When pressed deep, this key serves as the illumination color selector (initially in amber).
@ AUTO
@ Tuner AUTO ON/OFF key (initially ON)
@ With rear SDK ON, this key serves as the SK SEEK (UP) key.
@LO AME
@in the TUNER mode, when pressed slight, this key serves as the LO/DX selector.
When pressed deep, auto memory is started. For auto memory operation, refer to a separate section.
@ With rear SDK ON, this key serves as the display content selector.
In TUNER made (common to 1 to 0):
@ When pressed slight, this key acts to call preset channel 1.
@ When pressed deep, this key acts to write to channel 1 the station frequency being now received.
@ For direct access, this key serves as a numeric value input key. For direct access, refer to a separate section.
in TAPE mode:
This key performs a DOLBY NR mode selection in a order as follows:
KEY IN KEY IN
Initially OFF
KEYIN- ms
(The NR setting is memorized unless initialized.)
n CD-CH mode: Not effective
n TAPE made:
This key serves as the blank skip SKIP ON/OFF key (initially OFF).
In CD-CH mode: Not effective
n TAPE mode: T-CALL ON/OFF key
n CD-CH: Not effective
n TAPE or CD-CH mode:
One-tune repeat ON/OFF key (initially OFF)
* The ON/OFF state should be memorized independently between these two modes.
n TAPE mode: Index scan ON/OFF key (initially OFF)
n CD-CH mode: Track scan ON/OFF key {initially OFF,
* The ON/OFF state should be memorized in either mode.
n TAPE mode: Not effective
n CD-CH mode: Disc scan ON/OFF key (initially OFF;
n TAPE mode: Not effective
n CD-CH mode: Random play ON/OFF key (intially OFF)
n TAPE mode: Not effective
n CD-CH mode: Memory play ON/OFF key
For memory play, refer to a separate section.
Tuner memory key
Tuner memory key

Key Name
KRC-851D
CIRCUIT DESCRIPTION
Function
DIRECT
In TUNER mode:
Direct access ON/OFF key
Direct access function bases on the standard specification.
In CD-CH mode:
@ When pressed slight, the direct track/disc access numeral keys input standby mode is engaged.
@ When pressed deep, the memory mode is engaged.
{In the memory mode, when this key is pressed slight, the memory is firmly set and the next tune setting is waited for. For memory set
function, refer to a separate section.)
In TAPE mode:
Not effective
@ When pressed slight, this key serves as the tuner ON/OFF key or, in operation on another mode, the tuner call key.
When the TUNER key is pressed in operation on another mode when the tuner is ON, the TUNER made should be to by TUNER ON,
not performing TUNER OFF.
@ When pressed deep, this key serves to turn the power OFF.
in TUNER mode:
AM band select key
@ For J, K or Middle and Near East spec., this key works to call the MW band only.
@ For E spec., this key serves as the MW/LW band select key. When the FM band is engaged by use of the FM key from the LW band
and then the AM key is pressed again, the LW band should be returned to. (Same to MW)
In CD-CH mode:
Disc search (DOWN) key
@ For clock adjustment mode
Hour’s digit adjustment key
Clock adjustment bases on the standard specification.
In TUNER mode:
FM band select key, which acts to call FM1 or FM2.
When the AM band is engaged by use of the AM key from the FM2 band and the FM key is pressed again, the FM2 band should be
returned to. (Same to FM1)
In CD-CH mode:
Disc search (UP) key
For clock adjustment mode
Minute’s digit adjustment key
Clock adjustment bases on the standard specification,
© For destination J, this key serves as the clock key, which selects between clock display priority mode and clock display invalid mode.
Clock function bases on the standard specification.
®@ For destination K, this key serves as the valet key.
For its specification, refer to the plan specification.
* The key relative to the function in which a 4-bit code prevents the turning ON of the power by another hand.
@ For destination E
SDK ON/OFF key
SOK function bases on the standard specification.
@ For destination L
P-SCAN key
CD PLAY/PAUSE
@CD charger PLAY/PAUSE key
For CD charger function, refer to a separate section.
@ When no use of CD-CH control is specified, this key serves as the SA key for destination D, L or J or as the P-SCAN key for destination
K.
n TUNER mode:
DOWN-direction tuning key
n TAPE mode:
REW key (DPSS when pressed slight two touches and simpie REW when pressed deep)
n CD-CH mode:
Track search OOWN key
n TUNER mode:
UP-direction tuning key
n TAPE mode:
FF key (DPSS when pressed slight two touches and simple FF when pressed deep}
n CD-CH mode:
Track search UP
For cassette tape: STOP (=PAUSE) or EJECT key
Key input during play: PAUSE
Key input during pause: EJECT
PLAY/PROG
in TAPE mode: PLAY/PROG key
Tape play select key
17

KRC-851D
CIRCUIT DESCRIPTION
INITIALIZE
PON 5V
43 42 40
MODEL
CLK | DATA | CE
0 0 r 0 KRC-919 (J)
0 0 1 KRC-818 (J)
0 1 0 KRC-810 {K)
0 1 1 | KRC-910 {k)
1 0 1 KRC-851D (D)
GND

KRC-851D
CIRCUIT DESCRIPTION
IC6: LC7218 External PLL IC
XIN X OUT
CE VSS
DATA IN
CLK PD
DATA OUT VDD
SY FM OSC IN
SD AM OSC IN
MT FM
T/R
LOCAL
AFC AM
BS
AGC
External PLL Port Assignment
LC7218 Port Functions
Function
Stop level detect port, active “L”.
Effective for FM, MW and LW.
Band mute detect port, active “H”.
Effective for FM.
Note: For MW or LW, SD1 only is detected. For FM, SD1 and SD2 are detected.
For timing, refer to the timing chart.
“L" output during TAPE mode and “H” output during TUNER mode. (With power
OFF or ACC “L”, keep as it stands.)
Local control output.
“H” with local ON (“H” only during tuning operation because of local seek
operation).
FM AFC time-constant select output.
Active “L” during tuning operation.
AM AGC-CUT output.
Active “L” during tuning operation.
AM band selector.
Effective for Europe band.
“L" for MW, “H” for LW and “H” for FM.
AM+8B, Active “L”.
FM+B, Active “L”.
19

KRC-851D
MECHANISM
DESCRIPTION
Mechanism operation modes
Each mode undergoes the following sequence:
(A)
(B)
(C)
(D)
(E)
.
F)
i
LOADING/EJECT
STANDBY
REW
FF
FWD
REV
|
FR
plate
|
PRO
plate
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