Kenwood KR-A4010 User manual

AM/FM STEREO RECEIVER
KR-A4010
SERVICE MANUAL
Panel* Metallic cabinet
(A20-) (A01-1746-01)
KENWOOD ier sipcness rnin Rasxaord
KENWOOD
© 1989-5 PRINTED IN JAPAN
B51-3894-00 (O) 3012
Front glass
(B10-1006-03)
Phone jack Knob
(E11-0162-05) = (K27-1987-04) x 2
Lock terminal board * Bindinng post
{E20-) (NO8-0128-35)
FSot* Phono jack
(J02-) x 4 (E13-0446-05)
Slide switch *
($31-2136-05)
Phono jack
(E13-0621-05)
Knob
(K29-3598-04) X4
Terminal board
(E20-0823-05)
AC outlet*
({E03-)
Slide switch
(S31-2132-05) (E30-)
Knob
(K29-3597-04)
Knob Knob
(K27-1725-04) (K29-3632-04)
Slide switch *
($31-3010-05)
Power cord bushing
(J42-0083-05)
AC power cord*
* Refer to parts list on page 38.

KR-A4010
CONTENTS
DISASSEMBLY FOR REPAIR ..............::c::seseeeseeeees 3 ADJUSTMENT ....0......ccccescccssesseceeseeeeneeseneenseensees 16
BLOCK DIAGRAM ............:.:::cccseceeeeeeseeeteeeeeseseneeeenee 5 REGEAGE: occ. civcancsccarieceaseseced caccessce cdelassssnrostactqeazes 17
CIRCUIT DESCRIPTION PABGLEICH oii ics sccesscciecieaceccaacve ctusecttseeteccdesoeseeseet 18
1. Description of components ............::::cseeeeeseeees 6 ADJUSTMENT/REGLAGE/ABGLEICH ................. 19
2. Microprocessor uPD7538AC-041 VOLTAGE: TABLE oes. cs. hcsccscccescbccccneendetediesncestcctes 20
(X11-2650-10 2 1C1) oo... ceeeeceeeeeeseeeereeeeeeeseeeenenesenes 7 PC BORD (COMPONENT SIDE VIEW) .............06 21
3. PLL CX7925B (X14-2540-10 : IC2) ..... ec eeeeseees 13 PC BORD (FOIL SIDE VIEW).............ccsscsssrscsersees 25
4. FM MPX AN7470 .(X14-2540-10 : 1C3) .............. 14 SCHEMATIC DIAGRAM ..............:ccsccsessereesersenecsenes 29
5. STK4171/5 : Main amplifier EXPLODED VIEW.............::.::ccescccssseeseseeensensneenseennee 37
(X14-2542-71: 1C7) : T, E type ........::sseseeeeeeees 15 PARTS: LIST: ii silceceses ees atieseiiln asec rece aateesa haste: 38
6. STK4172/2 : Main amplifier SPECIFICATIONS ............:cssseeeeeeeenenens BACK COVER
(X14-2540-XX : 1C7): K, P, M, X type..............006+ 15

KR-A4010
DISASSEMBLY FOR REPAIR
Befor repair work, take out the case.
1. Remove the five screws, then detach the front panel
(@).
2. Remove the two screws then undo the catch of the
sub panel (@ ).
3. Remove the one screw (@ ).
4. Undo the catch of the PHONES, then detach the
PONES boad (X14-) (B/3) (@ ).
5. Detach the knob using a screwdriver (@).
6. Undo the catch, then the knob (@).
7. Remove the one screw (@) and the one hook (@),
then detach the PCB.
8. Remove the one screw (@), then detach the power
switch.
9. Remove the six screws (@) and the twelve
screws (@ ), then detach the display board (X11-)
(A/2).

KR-A4010
DISASSEMBLY FOR REPAIR
When repairing or checking the main PC board and
power supply refer to the following steps.
1. Remove the five screws (@).
2. Remove the six screws (Q ).
3. In this way, the FM terminal mold will hit against
the chassis. To avoid this, lift up the main body
putting aside the rear panel in the direction of an
arrow (@)(@).

KR-A4010
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KR-A4010
CIRCUIT DESCRIPTION
1. Description of Components
CONTROL UNIT (X11-265X-XX) 0-10: K,P 0-21:M 2-71:X,T,E
Part No. Use/Function Operation/Condition/Compatibility
IC1 pPD7538AC-041 Micro computer
IC2 PST529C Reset
Q2 2SA733 (A) (Q,P) Cannel space selection ON : 9kHz, 50kHz OFF : 10kHz, 100kHz
2SA933S (Q,R)
Q3 2SA733 (A) (Q,P) Indication driver TUNED display
I 2SA933 (Q,R)
Q4 2SA733 (A) (Q,P) Indication driver STEREO display
2SA933 (Q,R)
Q5 2SC945 (A) (Q,P) LED driver For PHONO
2SC1740S (Q,R)
RECEIVER UNIT (X14-254X-XX) 0-10: K,P 0-21:M 0-71:X 2-71:T,E
Part No. Use/Function Operation/Condition/Compatibility
| 1C1 LA1265 FM/AM system IC FM IF amplifier detection and control : AM mixing, IF amplifier and derection.
IC2 CX-79258 PLL IC for frequency synthesizer PLL for electronic tuning.
IC3 AN7470 MPX IC MPX demodulator.
IC4 NJM4558D-A Equalizer amplifier Equalizer amplifier for PHONO (MM).
M5218P-A
IC5 LC7820 Input selector SW Analog switch for input selector switches.
C7 STK4172/2 Main amplifier Main amplifier (2ch). (K,P,M,X type)
1C7 STK4171/5 Main amplifier Main amplifier (2ch). (T,E type)
IC8 PC7812HF Constant voltage power supply 3-pin regulator for the +12V constant voltage supply.
Qi 2SK241 RF amplifier High-frequency amplifier. (K,P,M,X type)
Qi 2SK73 RF amplifier High-frequency amplifier. (T,E type)
Q2 2SC1923 (O) Mixing Frequency converter.
Q3 2SC1923 (R,O) OSC Local oscillator.
Q4 2SC1923 (R,O} OSC buffer OSC OUT (oscillator output) for synthesizer.
Q5 2SK161 (Y,GR) OSC buffer For local oscillator input to mixer. (T,E type)
Q6 2SC1923 (R,O) FM IF amplifier 10.7MHz amplifier.
Q7 2SC1845 (F,E) LPF Low pass filter for PLL.
Q8 2SC1740S (Q,R) LPF Low pass filter for PLL.
2SC945 (A} (Q,P}
ag 25C1740S (Q,R) Buffer Buffer for L6 (T,E type)
2SC945 (A) (Q,P}
Q10,11 25C1740S (Q,R) Emphasis switch ON for 75s, OFF for 501s. ( M type)
2SC945 (A) (O,P)
Q12 DTC124ES FM + B control
Q13 DTA114ES FM + B control
Q14 | DTC124ES AM + B control
Q15 DTA114ES AM + B control
Q17,18 25C2878 (B) Muting TAPE REC OUT pop noise prevention during switching selector switch.
Q19 2SA933S (Q,R) Muting control Main amplifier pop noise prevention during switching selector switch.
2SA733 (A} (Q,R)
Q20,21 2S$C2878 (B) Muting Main amplifier pop noise prevention during switching selector switch.
Q22 2SA933S (Q,R) Muting control
2SA733 {A} (Q,P)
Q25 2SA933S (Q,R) Muting Main amplifier pop noise prevention during switching power switch.
2SA733 {A} (Q,P)
Q26,27 2SC1845 (F,E) Protection
Q28 2SA945 (L,K) Regulator power supply Output transistor for 24V control voltage supply.
Q29 2SA933S (Q,R} Error amplifier -12V error amplifier.
2SA733 (A) (Q,P)
Q30 2SA945 (L,K) Constant voltage circuit -12V
Q32 2SC2003(L,K) Regulator power supply Output transistor tor 5V constant voltage supply.

CIRCUIT DESCRIPTION
2. Microprocessor 1. PD7538AC-041 (X11-2650-10 : IC1)
Terminal connection diagram & key matrix connection
KR-A4010
Lil
| | Reset ves 2
2 4!
| |-=e cli POO/INTO
33
Ca
|
vest
PO3/S!
(vem)
AUTO STEREO P53 P30 or
PHONO/MAIN 2 P52 P31 >
SUB
<7
PSI
P32
Pe
(1)
(>)
MUTE
P50
P33
od
ap
-
ee?
bae
~
©
|
SEG
P40
CX7925S
!
j
A
CLK
3
P2I7POUT
P42
=
9
coveann «<2 Pi03 P43 = a >h pai
Tuner
«<4
pioz
P80
i!
i
5
i5 28
VIDEO/TEST <= PIO! Pal fo |
TAPE/Bilingual
=
P100
P82
=
2
ae
|
To
$0 8 PUB (ee P83 25 3 | Grip la >t Video (co)
CE Pil2 P30 4
DATA = PI P9l 24 5.
BUSY PIO P92 6
Voo P93 POWER
LiL
Block diagram
POO/INTO
ZERO-
CROSS
DETECTOR
CLOCK
CONTROL
TIMER/EVENT
COUNTER
INTERRUPT
CONTROL
P80
PO1/SCK
PO2/SO
SERIAL
INTERFACE
PROGRAM MEMORY
INSTRUCTION
4096x8 BITS
DECODER
SYSTEM
CLOCK
GENERATOR
STANDBY
CONTROL
CLI CcL2 Vop Vss_ «RESET
GENERAL REGISTERS
STACK POINTER(8)
DATA MEMORY
160x4 BITS
Bond Bond
fo) |
PO3/S1
-_
Band Band
2
"8
Vere VioAD
| lee POO-PO3
PORT2
LATCH
BUFFER
P2I-P23
PTOUT/P2!
LATCH
BUFFER
PORT4
K_ LATCH K 4 pao-pa3
BUFFER
PORTS
LATCH
BUFFER
PORTS
LATCH
BUFFER
PORTS
LATCH
BUFFER
| 4) P90-P93
PORTIO
LATCH
BUFFER
K"4_) P100-P103
PORTI1
LATCH
BUFFER
K 4) PO-PH3

KR-A4010
CIRCUIT DESCRIPTION
Function of the diode switch
1. Models for each designated area and function setting switches
Model for desig- Set switch Receiving Channel Reference Middle
nated area Band 3|/Band 2/Band 1 frequency range spacing frequency frequency
87.5 ~ 108 MHz 100 kHz 50 kHz 10.7 MHz
530 ~ 1610 MHz 10 kHz 10 kHz 450 kHz
4
87.5 ~ 108 MHz 50 kHz 50 kHz 10.7 MHz
531 ~ 1602 kHz 9 kHz 9 kHz 450 kHz
163 ~ 281 kHz 1 kHz 1 kHz 450 kHz
0 0
K type or E type (without LW)
Band 3 H Overseas
L Domestic (Japan)
Band 2 H FMch space 50 kHz & AMch space 9 kHz
L FMch space 100 kHz & AMch space 10 kHz
Band 1 H Without auto tuning function only for LW broadcast
Band 0 H With LW: Indication (FM, MW, LW)
L Without LW: Indication (FM, AM)
LW key is not accepted.
2.
Stop
frequency
select
switch
for
auto
tuning
in
LW
@
Setting
of
this
switch
can
be
changed
without
reception
resetting
(unplugging/plugging
the
AC
cord.)
This switch is used to set the frequency which intakes
the SD signal in LW band reception. For both manual
and auto tuning, the tuning frequency is changed up or
9N-+ 2 |Frequency/Channel|Reference| Middle Stop
/9N range spacing | frequency | frequency frequency
down in 1 kHz step, however, in auto tuning mode, the 153 ~ 155, 164 .....
ae
1
281
kHz
|
1
KHz
1
kHz
450
kHz
|
525587
KH
receiving frequency stops at the following frequency = : :
163 ~ 153, 162...
selected by this switch. | o | 281 kHz 450 kHz | 950979 KHe
3. Auto tuning 4. Others
Auto tuning
Auto tuning function
Auto/Mono KEY Function
Preset 16
Preset 20
1 | Not available Mono/Stereo function only
0 Available This key is also used as the Auto/Man-
ual tuning mode key
Set switch
6)
1

KR-A4010
CIRCUIT DESCRIPTION
Port allocation
Function
Key return signal input
Key return signal input
Key return signal input
Key return signal input
PLL IC (CX7925B)
Function SW (LC7820)
Data output
PLL IC (CX7925B)
LAT output
PLL IC (CX7925B)
CLK output
oO} w
FL display segment output:
nN
Tyr} rT {Tz} TT TTT
a
T
Function SW (LC7820)
Key strobe signal output.
Key strobe signal output,
FL display segment output:
Key strobe signal output.
FL display segment output:
Key strobe signal output.
FL display segment output:
-1O}W!/N
xrjxrjrl/t
Key strobe signal output,
Key strobe signal output.
FL display segment output:
FL display segment output:
(0)
| oOo | H
i)
pa ef Key strobe signal output,
FL display segment output:
Key strobe signal output,
FL display segment output:
TFIO;T/MDIQl o;T]o
Key strobe signal output
oO
FL display segment output
FL display digit control pin: GRID 1
FL display digit control pin: GRID 2
FL display digit control pin: GRID 3
<
—-}O!}a
NIN w ames) oO
bf
t
T
lox Ke)
x }Tl/TyryTt
.|
Power supply input pin (5V)
FL display digit control pin: GRID 4
FL display digit control pin: GRID 5
FL display digit control pin: GRID 6
Input port: TV mode “Bilingual” pin (H)
Output port: Receiver selector “TAPE”
Input port: TEST pin (H)
Output port: Receiver selector “VIDEO”
Receiver selector “TUNER”
Receiver design: Receiver selector “CD”
System component design: Band data output (UHF: H)
Serial signal BUSY pin
Serial signal DATA pin
Back up detection pin
Station detection pin for auto tuning mode
OWN} -|O] w
=
Muting signal
TV SUB pin
Receiver design: Receiver selector “PHONO”
System component design: TV MAIN pin
Stereo (L)
MONO/SST key to control Mono (H)
Reset signal
Clock
Clock
Power supply for FL display pre-driver
Power supply for FL display driver (— 30V)

KR-A4010
10
CIRCUIT DESCRIPTION
Key matrix layout
POO (41) PO1 (40) PO2 (39) PO3 (38)
P30 (37) UP DOWN
AUTO
MONO
Preset
P31 (36) Scan
P32 (35)
——_--+
P33 (34) |
P40 (33)
Sound
multiplex
P42 (31) i cD
* Auto
tuning
P41 (32)
*16 Preset
20 Preset
P43
(30)
Receiver
@ Values in brackets (
*
Band 1 *Band 3
*Band 2
) shows the pin number of
P80 (29)
microcomputer.
@ items with an asterisk (") shows the diode switch.
Others are momentary switches.
@ LW (9N+2/9N) is the slide switch on the rear panel.
@ Key-intake is active high.
Tuner function
1.
Manual tuning
Each time the UP/DOWN key is pressed, the tuning
frequency is varied one step higher or lower. When this
key is kept pressed for more than 0.5 seconds, the
frequency is changed up or down at approx. 128
msec/step (approx. 224 msec/step for TV reception)
until the key is released.
. Auto tuning
When the AUTO/MONDO switch is set to AUTO, press-
ing the UP/DOWN key starts auto tuning. The tuning
frequency is changed up or down at approx. 128
msec/step (approx. 224 msec/step for TV reception)
until the high-level signal is input to the SD pin. When
the high-level signal is input, auto tuning operation
stops.
. Preset memory
Up to 16 or 20 frequencies (the maximum number of
preset stations is set by the diode switch) can be preset
randgmly for FM, MW (AM) and LW (TV) stations.
a) How to preset
When the MEMORY key is pressed, the MEMORY”
indicator lights and the unit is set to the write-enable
Status. Writing to memory is possible for approx. 5
seconds after the MEMORY key is pressed. During this
time, pressing any of the numeric key (1 — 10) will write
the currently-received frequency into memory corre-
sponding to the key pressed.
b) How to recail
When the tuner functions, pressing any of the preset
keys will recall the stored contents corresponding to the
key pressed.
. Preset scan
When the PRESET SCAN key is pressed, the SD pin
goes high level. A preset channel is received for 5
Test frequency
530 | 630 |
@ Test mode set-up: :
FM
87.5 89.1
AM
ee
1440/1602] 153
Set the test pin (P15) to high level, and invert it
to low level after turning the power ON. (The entire!
FL display will light except for MEMORY.)
seconds, then the receiving frequency is changed to the
next preset channel. When the SD pin is low level, the
receiving channel is changed to the next preset channel
after one second.
a) Key processing during scanning
@ Preset key: Stops the scanning operation and
receives the frequency of the designated preset
channel.
@ UP/DOWN key: Stops the scanning operation and
processes the UP/DOWN function.