Kenwood KRC-754 D User manual

STEREO CASSETTE RECEIVER
KRC-754 D/L
SERVICE MANUAL
é “a
KRC-754D
Knob (REW)
(K24-1131-04)
— si =
KRC-754.
seseermaaie
:
seascape
—

STEREO CASSETTE RECEIVER
KRC-754 DIL seer eeere
SERVICE MANUAL
©1992-7 PRINTED IN JAPAN
B51-6513-00(B) 2065
Knob (EJECT)
KRC-754D (K24-1129-04) Knob (REW) Knob (FF)
(K24-1131-04) (K24-1130-04) Knob (TUNE)
(K25-06 13-03)
Knob (SOURCE)
(K24-1143-04)
Knob (VOL)
(K23-1020-03)
Panel assy Front glass Knob (AM, FM)
(A20-7862-02) (B10-1510-03) (K25-0605-03)
KRC-754L
Panel assy Front glass
(A20-7863-02) (B10-1511-03)
Mounting hardware
{J21-7088-71)
THEFT DETERRENT FACEPLATE (assy)
(not supplied as service parts}
¢ TDF-754D
Stay
(J54-0059-04)
Lever
(D10-2740-04)
Plastic cabinet
(A02-1413-11)
° TDF-754L
Screw set
{N99-1570-05)
DC cord
(E30-4007-05)

KRC-754 D/L
CONTENTS
CONNECTION i csicctiecre 5628 Srestheetten cede: bot aeesvithnr stevens 2
DISASSEMBLY FOR REPAIR .........ccc eee eeeceeesteeeeeeeeeeene 3
BLOCK DIAGRAM uu... ceccccecccecceseecseeeeseeseresneaeseceseeeeseeenees 5
CIRCUIT DESCRIPTION .0....cc ee ce steeneceeesereeeseeeeneees 6
MECHANISM DESCRIPTION ou... ccecccteeeeseeeeeeeeees 16
ADJUSTMENT ascsccccteccossccccesonsesesscccecsscecesstedeseedecsvsoessatones 22
ABGLEIGCH: ficssacscees.ccstecededszecsessesesacessasteteapaoresss igen sebennsbasye 24
Output
KENWOOD:
= we>
oO u
FM/AM
antenna KENWOOD CD-Changer
(Option) Output
CD-Changer control output
<i eo CO)
Rear right output (Red)
KRC754D/L
Power connection
cord (Accessory)
Power control supply lead (Blue/White)
(Full automatic Power antenna control lead)
Power supply lead
(Red) ® (To ignition)
i
d b
Memory backup lead
(Yellow) ® (To battery)
Ground lead (Black) © (To car chassis)
Automatic illumination 7Dimmer control lead
(To light control switch )
ILLUMI
| AWARNING|
4
@To prevent fires from occurring when
the Power supply lead (Red) and Memory
Backup lead (Yellow) are short-circuited
by accidentally coming into contact with
the chassis (ground), connect the power
supply after fuse box connections have
been made.
(White stripe)
SS @
[FRONT
-)
core
left
mere
1G
ee
left
Ste]
speaker
(Gray snipey
ae Front right
speaker
[FRONT -) Eieee st "S
(Green so)
—is 05
[REAR* t ) Rear. ast
Fie |
(Purple stripe)
ci)
pees. as
Rear left
speaker
Rear right
speaker
Changer extension cord
(Provided with the
KENWOOD CD-Changer)
Rear left output (White)
PG BOARD eivcessicsitas edie ctedicsevtns Bactssdeecdeeeeeve cane 25
SCHEMATIC DIAGRAM 0.0... ccccccccceseesesseescessessecesnaseaes 31
EXPLODED VIEW (MECHANISM UNIT) .........cccee cee 39
EXPLODED VIEW (UNIT) oo... cceccceceeeesccusenssaneeensssnees 40
PARTS: EIST | cscai coves tose sos Sec so ccessesvsetsdoudsienestaceticeeutens: 42
SPECIFICATIONS oo... eeeeeeeeesesesenseenes BACK COVER
@Since connections depend
on the CD-Changer used,
refer to the instruction
manual for information on
CD-Changer connections.
Rear
speakers
Power amplifier
(optional)
Power control input
Ignition key
switch
Car fuse
b
Car
fuse
box
m
(Main
;
fuse)
(Orange)
Battery
ACAUTION
@ When two speakers are connected to the system,
connect them as shown below.
Any other kind of connection will cause sound
distortion and damage to the speakers.
(White stripe)
Front left
speaker
Front right
speaker

KRC-754 D/L
DISASSEMBLY FOR REPAIR
1. To remove the control unit and the sub panel
1. Press unit removing button @ and remove the con-
trol unit.
2. Remove screw @ and remove the top cover.
3. Remove 4 screws @, pull out flexible harness @
and remove the sub panel.
2. To remove the cassette machanism
1. Remove the connectors and flexible harnesses @,
remove 3 screws @ and remove the cassette
machanism.
3. To remove the PC board
1. Remove 4 screws @.
2. Straighten claws @ with nosed pliers and remove
the cassette machanism.

KRC-754 D/L
DISASSEMBLY
FOR
REPAIR
4. To remove the control unit and the case
1. Remove 6 screws @.
2 While pressing front case @ up and rear case @
down, open the bottom of case @.
Pay attention to claws @.
3. When assembling, insert 4 springs @ into the rear
case holes.

KRC-754 D/L
BLOCK DIAGRAM
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KRC-754 D/L
CIRCUIT DESCRIPTION
(X14-3662-XX)
Component
Device Name
Purpose, Function
Operation, Condition, Compatibility
HA12134AF
Dolby B type
BA3121F Isolation Amp
Tape and tuner mode switching, Dolby B type
decoding.
CD-CH isolation amplifier.
TC4066BF Analog SW
Dolby out and CD-CH mode switching.
IC5
NJM4565MD
TC9233FK
1/2 Vec Buff
E-VOL
IC6
IC7~10
NJM4565MD
NJM4565MD
VOL2 out Buff
Tone control
IC11, 12
NJM4565MD
AN7174K
FAD Buff and Pre Amp.
PWR Amp.
AN7465S
FM MPX, NC
FM stereo detection and noise canceling.
TDA1579T
NJM4565MD
SDK IC
(KRC-754D only)
IF composite sig Buff
Composite signal buffer. BK BPF.
SN74HC367ANS
CD-CH 1/0
1 7006GF-531-3B9
Master p-COM
BA3906-V 1
AVR
Supplies Vop (5.6 V), COM 8 V, FM 8 V and AM 8 V.
DTC144EK
DTC144EK
Sig SW
Sig SW
OFF: CD-CH.
ON: CD-CH.
2SD1757K Audio Mute
2SC2412K CRSC Driver
DTC144EK Compulsory monaural SW
2$C2412K
DTC144EK
ANRC Buff
SK INH SW
(KRC-754D only)
2SA1428 Motor driver
DTC114EK
Motor driver SW
|
2SB1370
28C2412K
ILL AVR
DTC144EK
DTC144EK
2SA1428
ILL AVR cont SW
ILL+B (Gr) SW
2SA1428 ILL+B (Am) SW
DTC144EK
ILL+B (Gr) SW
DTC144EK
ILL+B (Am) SW
DTA144EK ILL DIMMER SW
DTD123YK
2SA1037K
ILL DIMMER SW
Mute driver
DTA144EK
High-speed mute driver

KRC-754 D/L
CIRCUIT DESCRIPTION
(X14-3662-XX)
Component
Purpose, Function
Pack in Mute SW
Tape Mute INH
Power SW DET
Mecha Mute SW
SD INV
AM SD SW
FM Lo/DX SW
Device Name Operation, Condition, Compatibility
DTC144EK
DTC144EK
28C2412K
28C2412K
DTC144EK
28C2412K
Q39 DTC144EK
Q40 DTA144EK
Q32
SW for muting during FF, REW and PROG.
AM Band SW
MW/LW switching. (KRC-754L only)
Q41 DTC144EK
Q42 DTA144EK
AM AGC CUT SW
043 DTC144EK
044 DTA124EK P-cont OUT driver
DTC144EK P-cont driver SW
Q46 2SA1037K ;
P-cont OUT driver
Q47 2SB1277
Q48 DTC144EK ILL DIMMER SW
laag «| 2SK669 PLL LPF 7
PWR Amp Mute SW
lass | DTC 144EK
Q56, 57 DTC144EK ACC. B.U DET Detects ACC and BU voltages and controls the
los8 28C2412K aa power amp ST-BY and »-COM CE.
DTC144EK -
lasg_s(pTCi44eK AVR STBY cont Controls ST-BY of the system AVR (IC25) and
Q60 DTA144EK switches P-on 5 V.
Q61 DTA144EK P-on 5 V driver
Q62 DTA144EK CE 5 V driver
Q63 DTC144EK ACC, B.U DET Mute SW
(X86-1272-71)
Component Device Name Purpose, Function Operation, Condition, Compatibility
IC1 BA3430F Tape EQ Amp
LA1140 FM IF Amp FM IF sig Amp
PST529E-MT Reset IC
28C2413K FM IF Amp
| DTC124EK FM Mute cont OFF during seek.
28C2412K FM S-Meter Buff
DTC144EK AFC SW Switches the time constant of AFC terminal.
DTC114EK T-ADV SW
28A1428 Planger driver ,
DTC144EK
2SA1428
u-COM RESET SW

KRC-754 D/L
CIRCUIT DESCRIPTION
1. Summary
The
following
specifications
refer
to
the
microcomputer
software
used
with
the
cassette
destined
to the U.S.A. and Europe.
The
uPD177006GF
is
used
because
the
circuits
are
designed
in
common
with
other
models.
Product outline
* Theft prevention by detachable panel
Key input by means of A/D converter input.
Display using external LCD driver.
Volume
control
using
electronic
volume
control
(input
from
rotary
encoder).
2. List of short descriptions of functions
eae,
is
K-TYPE
|
D-TYPE
|
L-TYPE
be
Description
|
GENE-
|
CLOCK
O
Oo
Oo
Clock
function.
may
Electronic
volume
©)
O
Oo
Controls
1C9233
from
Toshiba.
|
Lounxess
=
©
O
O
Same
as
above.
ATTENUTOR
O
O O
Same
as
above
(-20
dB).
2-color
illumination
O
oO
|
oO
|
Color
switching
of
panel
illumination.
BUZZER
O
O
O
Key
Sensor
Tone
ccaie
met
[|
|__|
Ri
lvl
section
HEY
Auto
illumination
O
O
O
Illumination
is
turned
ON
when
the
car
RADIO
|
Destination
switching
|
KN
Type
x
FM
3
3 3
FN
Preset
6
ch
x
3
Band
BAND
[AN
(NW)
I
1
ee
|
[
CL¥)
(a
x
NW,
L¥mix
PRESET
6
6
6
|
TUNING
UP/DOWN
|
UP/DOWN
|
UP/DOWN
LOCAL
SENS.
i
oO
Oo Oo
Seek
stopping
sensitivity
switching.
AUTO
MEMORY
Oo
O
oO
NONO
x
O
O
cme
monaural
mode.
|
SDK
|
x
Oo
x
ARI
function.
PRP
Oo
x
O
Priority
Radio
Preset
|
TAPE
|
WETAL
©
O O
Tape
Equarizer
TAPE
ADVANCE
O
O ©
|
Locate
the
beginning
of
a
tune.
a
TUNER
CALL
O O O
Pies
radio
sound
while
fast
ed
DOLBY
B
O O
Of
Kore
REPEAT
a
Oo
O O
Plays
one
track
repeatedly.
—
TRACK
SCAN
oO
O O
Plays
the
first
10
sec.
of
every
track
DISC
SCAN
=|
Oo
@)
oO
Plays
the
first
10
sec.
of
every
disc.
Ie
RANDON
oO
Oo
O
|
Plays
the
tracks
in
a
random
order.
|

KRC-754 D/L
CIRCUIT DESCRIPTION
3. System configuration
Tuner module
ARE heme
i
i<>]
ea a POWER
ae ees a ANTENNA
= == OOO ~
1 A bet et © CO, oe et Be
ANNAN A Qt <t f <t oe
ILL. CE
ILL-A PCON(S¥5V) ———>
LCD_INH
LCD_CE TA/RA>
LCD_CLK SELECTER
LCD_DT
KEYS >
KEY3 ->| CuPD 17006GF - 4#* - 3B9) MUTE ————>
KEY2 > < SEL!
KEY] -> < SEL?
ENCA > R DT ——>
ENC_B
>
VR
CLK
——>|
E-VOL
Power
—>
VR_STB
———»
|
1TC9233F
OAR N Ow he 2o<c—- | |
Ha EOM~O Oo lee oeo
CO: orort<« |
oO SHA OOARmas
HHT TL ele
Manual Cassette CD Changer
Mecha (1/0 Box)
SPEAKER OUT

KRC-754 D/L
CIRCUIT DESCRIPTION
4. Terminal description
17006 GF-532-3B9 (IC24: X14-3662-XX)
Microprocessor iC
4-1 Pin layout
= mm |e RN — <
= me | ope ew w Ee met
On ~ = bx | Oe ( PO oO < eS
Io aO [= ot = / | a OO
Qe
=<
O
a)
oO
t=)
AQ
I
1]
Oo (aA fu © < wo oO io CH oe
n= OO ce fy i) [<> — > > >
Qn N oD oON =O on Nop on N oD
OO Oo aa aa OO Oo mr 4 [-o ==)
oT owe oe oe NA NN NN NN
a. AL A. A, OAL. A. Ay aA oA, a. A, A. AY
80 79 78 77 76 75 74 73 72 71 70 69 68 67 66 65
ADCS
Vdd2
64
|
———
Vdd
ADC4
P4A3
63
|
——>
KEY4.
——»>
ADC3
P4A2
62
|
——>
KEY3
——>
ADC2
GND2
———
GND
KEY2
——>
ADC1
POA3/SDA
<+—
REQC
KEY
==>
ADCO
PQA2/SCL
59
|
——®
REQ_H
P1D3
POAI/SCKO
+—
CH_SCK
1
2
3
4
H)
6
7
8
9
ENC-B
——-»
P1D2
P0A0/SO00
<+—»>
DATA_H/SEL1
PANEL
———>
P1D1
P0B3/S10
+—
DATA
SMALL
——>
P1DO
POB2/SCK
1
<—»
KEY4/LCDCLK
POWER
—-—>
INT]
POB1//SO01
<—-»
KEY3/LCD_DT
ILL-A
<«—~—
P1C3
uPD
17006GF
POBO
———>
ILL-B
<«<——
PIC2
—-*x**xx*x—-—3B9
P2A0
==
Vdd
———
Vdd0
P2Al
<—
—>
Vcol
P2A2
<_—-
—->
Vcoh
P2A3
oe
gs
GND
———
GNDO
PIA0
——>
AFC
<——
E0bst
PIAl
——>
AGC
<—
E00
PIA2
——>
LW/M¥
+—
E01
P1A3
<+—
SEL2
DOLBY
<——
P3C3
P3A0
+—
SD
MONO/ST
<«——
P3Al
<+—
DKIN
METAL
<«——
P3Cl
P3A2
+—
SKIN
TAPE/RADIO
«——
P3C0
P3A3
+—
STIN
25 26 29 30
31
32
33
34
35
36
37
38
39 40
<4+—.
qo
‘q2 4 =
~<——,
4+ | x +
+
+——
——>» —
——>
oe
oONI a) on oD Sn med => ON OS
[aa - 2) [-o-2) eo a As ee) Aaa aa
—e
Sania!
zs
moo
zo
cet
et
NS
NN
a, A, A. A — On Om <O A, A, A. AL
ma, no} Qz aD NE Za oo
e =] oOo Za mo oo aa
> w > QO oOo . =O Oo ~N
= “4 = = A, = Y | 3
4 O <= O}]m
ht a
(Note)
Pins
25
to
27,
59
and
60
are
N
CH
open-drain
terminals.
10

KRC-754 D/L
CIRCUIT DESCRIPTION
4-2. Terminal descriptions
I
S-MET
2 | ADC4 I | MUSIC
Function
Detection of stopping level of radio FW band seek.
Blank-between-tune detection input for T-ADV.
I | KEY4
Key input for use by ADC. (Resistance type potential division
to 4 CH)
Key input for use by ADC. (Resistance type potential division
to 4 CH)
Rotary encoder input for electronic volume control.
Detachable panel detection SW. (”Hi” when detached)
Car small light S¥ detection input.
ae ie Power SW (switch incorporating rotary encoder).
[rea [© a [ieitin Ge tt er tt he et
is rice [© [ise [iieition Grae) it. Pe ott toe Fon pe.
EC
2 D
22 | P3C2 MONO Compulsory monaural output.
23 | P3Cl
10
1
Tape equalizer control output.
—
24 | P8C0
T/R | Tape/Radio audio switching. "Hi” with radio or CD changer.
Hee
25 | P1B3
(N. C)
(N. C)
MUTE Audio muting output.
BEEP Sensor tone output.
N.C
CE Power down detection input.
ILLCON Illumination main power output. (Cassette _ lighting)
0 | CKOUT System clock adjustment terminal.
0 | PCON System power control output.
11

KRC-754 D/L
CIRCUIT DESCRIPTION
i [i [0 [ Pr
Function
P2D2 ANCON
Radio
AM
band
switching
output.
(”"Lo”
during
FM
band
or
with
other
sources)
Local sensitivity control output.
39 | P2D1 L0.S
40 | P2D0 FM/AM
FM/AM
switching
power
output.
("Hi”
with
other
sources
except
SDK)
AFC control output.
STIN Stereo signal input.
SKIN SK signal input. a
DKIN DK signal input |
SD SD signal input for both FW and AM.
SEL2 Specification selection 2 (Europe D/L).
LW/NW Specification selection 2 (Europe D/L).
AGC AGC cut output.
AFC
CC
wie
[ja
ja
fren[e[
ao
52 | P2A0 0 (N.C)
53 | POBO 1/0 (N. C)
54
|
SOL
LCDDATA
LCD
driver
serial
data
output
(Sanyo
LC-7582).
55
|
SCKI
LCD_CLK
LCD
driver
serial
clock
output
(Sanyo
LC-7582).
:
56
|
SI0
DATA-C
CD-CH
serial
data
input.
o7 | S00 DATA-H CD-CH serial data output.
57
|
POAO
SEL]
Buia
renga
yea
S.
/Europe)
(Input
only
at
the
58
|
SCKO
CH_SCK
CD-CH
serial
clock
input.
59 | POA2 REQ-H CD-CH request output.
60 | POA3 REQ-C CD-CH request input.
62 | P4A2 (N.C)
63 | P4A3 0 (N.C)
12

KRC-754 D/L
CIRCUIT DESCRIPTION
Function
| No | Pin Name | 1/0 | Port Name
fe [rm [o [max
fer from [0 [oo
[row fo
[res |
70 [pace | 0 | LCD_CE1
Lo LCD_CE2
*
Electrical Volume Serial Clock (TC-9233)
Electrical Volume Serial Data (TC-9233)
(N. C)
(N.C)
LCD driver Ce 1 (Sanyo LC-7582).
LCD driver CE 2 (Sanyo LC-7382). KRC-754D/L is not used.
P2C1
rs [nsf
74 | POD2 PACKIN
75 | Pop. | 1 | FND/REV
76 | PODO Ee FF/REW Fast forward input.
rea fo [cmon [@ttene ome
ron | © [mr [te hs net owt
roo | @ [rr [Toe trot wt
POCO O | LCD-INH LCD inhibit output (Sanyo LC-7582).
EQ MUTE Tape equalizer IC muting output signal.
Tape pack detection input. (”Lo” with pack in)
Tape transport direction (forward/reverse) detection input.
al
13

KRC-754 D/L
CIRCUIT DESCRIPTION
4-3. Panel/main body connection terminals
Pin Name | 1/0 |} Port Name Function
0 | LCD _CEl LCD Driver CE 1 (SANYO LC-7582)
0 | LCD_CE2 LCD driver CD 2 (sanyo LC-7582). KRC-754DL is not used.
I GND GND
0 ILL-A Illumination (amber) output. Power output to the front panel.
0 ILL-G Illumination (green) output. Power output to the front panel.
I SMALL Car small light SW detection input.
I D_GND Digital grounding.
O | LCDDATA LCD driver serial data output (Sanyo LC-7582).
8 Key input for use by ADC. (Resistance type potential division
Key4
to 4 CH)
LCD_CLK LCD driver serial clock output (Sanyo LC-7582).
9 Key input for use by ADC. (Resistance type potential division
KEY3
to 4 CH)
r Key input for use by ADC. (Resistance type potential division
10 KEY2 to 5 cH)
[fo fang aT
to 5 CH)
i “1 [Porer [Power St Gwviteh incorporating rotary encoder).
E [0 [tco-nir [op inhibit output Gono Lowe).
i FT [xe-A [Rotary enewler input A for electronic volume cmtrol.
15 PT] ENG-A Rotary encoder input B for electronic volume control.
* The pin Nos. are assigned so that, with the front panel facing toward the front, the pin at the
top is pin 1.
5. Key description
5-1. Key matrix
Utilizing the ADC inputs, five kinds of inputs are available for each key according to the
input voltages supplied as shown in the circuit diagram below.
KEY] KEY2 KEY3 KEY4
S¥1 SOURCE (N.C) CLK @/SCN
SW2 ATT LOUD/TLLUM @/DOLBY @/T-C/DS
S¥3 LO. S/ANE PRP/SDK @/MTL/REP @©/RDM
SW4 AUTO/SK. S @®/T-ADV AN - FM +/NONO
SW5 = + CN. C) (N.C)
Keys ” -”, ” +”, "FM +” and "AM -” are assigned to the positions with the highest voltage so
that their ON or OFF can always be detected even when several keys are pressed simultaneously.
14

KRC-754 D/L
CIRCUIT DESCRIPTION
15
a
ees
Sl
ree
-
WCON
A/D
Port
LR
GND
(Note) S¥5 is not connected with KEY3 and KEY4.
6. Test mode
After the occurrence of Reset when Vdd is supplied, press and hold the ” 4” and "SDK(PRP)”
keys while press the Power key to ON to enter the test mode. (The test mode includes the cha-
nge of CE term inal from ”Lo” to “High” immediately after the power is switched ON. )
The test mode consists of the following processes.
Loud is turned OFF, Bass, Tre., Bal, and Fad. are set to “flat”, and the Volume level is set
to ”00dB”.
When the power is switched ON, the Tuner source, FMWi band and the last frequency are selected,
and the LCD is set to the all-ON state. However, if the test mode is initiated with a tape
inside the set, the set is turned ON with the tape source and the LCD is not set in the all-
ON state.
when the power is switched ON, the CKOUT output terminal outputs division (4. 19MHz) of system
clock for use in the adjustment of reference oscillation frequency of the clock.
When the Source key is pressed to ON or a tape is inserted, the LCD all-ON state is canceled
and the set enters the mode for S-meter adjustment.
In the S-meter test mode, the S-meter level for the F¥ band of the tuner source is adjusted to
20dB (0. 3V), and "> lights when the level is exceeded.
With the AM band, the SD level is adjusted, and “<Q” lights when SD is detected.
The S-meter test mode is not released even when the source is changed.
However, as it uses the ” <q p> ” display, which is usually used with the tape system, when a
source change is detected, the tape should not be in the set in this mode.
The test mode is released when the power is switched OFF then to ON, when panel is detached
then attached, or when CE changes from ”L” to "fl”. However, the states sect in the test mode
are not released and the current state is mainteined (except for Reset after Vdd is suplied).
15

KRC-754 D/L
MECHANISM DESCRIPTION
Azimuth screw

LO.
1.
2.
3.
10.
KRC-754 D/L
MECHANISM DESCRIPTION
ADING/PLAY
Insert
a
cassette
tape
(@).
The
cassette
guide
(65)
pushes
to
lever
(reverse
(121])
(@).
The
lever
(reverse
[121])
turns
in
the
direction
of
the
arrow
and
releases
the
lock
of
the
holder
(ac-
tion
piate
[61])
(@).
Through the lock release of the lever (reverse (121]),
the arm (action [53]) is pulled by the tension spring
(54), which turns the holder (action plate [61]). The
holder (action plate) descends (@).
Through the descent of the holder (action plate
{61}), the holder (cassette case [68]) also descends
(@).
As the holder (cassette case [68]) descends, the
cassette tape pushes the lever (lock plate [21]).
The lever (lock plate [21]) then releases the lock of
the lever assembly (head plate [2]) (@).
As the arm (action [53]) turns, the lock of the lever
assembly (eject [51]) is released (@).
The lever assembly (eject [51]) is pulled by the
tension spring (52) and moves forward (@).
Through the movement of the lever assembly (eject
{51)), the lever (102) also moves forward and turns
on the slide switch S1. As the slide switch $1 is
turned on, electricity is supplied to the motor as-
sembly (M1) (@).
As the holder (cassette case [68]) descends, the
cassette tape pushes the lever (lock plate [21))
then releases the lock of the lever assembly (head
plate [2]) (@).
. The lever assembly (head plate [2]) is pulled by the
tension spring (45) and moves forward (@).
17

KRC-754 D/L
18
MECHANISM DESCRIPTION
12. Through the forward movement of the lever as-
13. The rotation is transmitted from each gear (17-12)
PROGRAM
1.
2.
3.
sembly (head plate [2]), pinch roller assembly (6)
make close contact with the shaft of the flywheel
(17) through the formed wire spring (44) (@).
to the reel base (40) of the take-up side (@).
Push the FF and REW levers simultaneously (@).
The arm assembly (15) moves toward the right
(@).
The lever (31) is pulled (@ ), and the changeover
gear (32) is unlocked.
The changeover gear is pushed by the torsion
spring (33), and engaged with the cam gear (25)
(@).
The changeover gear (32) is rotated by a half turn
and locked with the lever (31) again.
The movement of the boss of the changeover gear
(32) moves the changeover arm (9) (@).

KRC-754 D/L
MECHANISM DESCRIPTION
7. When the changeover arm (9) moves, the drive
direction of the reel base (40), head switch (S2)
and pinch roller is switched between FWD and
RVS (@).
AUTO REVERSE
1. When the reel base (40) stops rotation at the end
of tape, the arm (38) stops pushing the sensor
lever (@).
2. The sensor lever is engaged with the cam projec-
tion of the cam gear (25) and carried until the inter-
mediate point of the cam gear (@).
REW
r) RVS
SENSOR LEVER
3. Then, the sensor lever is carried by the triangular
boss of the cam gear (25) and pushes the lock
lever (@).
4. When the lock lever is pushed, the changeover
gear rotates and the program operation starts (@).
FF 72
1. Push the lever FF (79) (@).
2. Pushing the lever FF (79) closes the leaf switch S4
(S3) and muting is applied (@).
on
3. The lever FF (79) is locked by the arm (72) (@). S3 eo (Al P, re
4.
By
pushing
the
lever
FF
(79),
the
lever
(8)
is
pushed
.
ames
\
in
the
direction
of
arrow
(
@).
@ALAS
a.
5.
Through
being
pushed,
the
lever
(8)
moves
the
“a0
he
ai
lever
assembly
(head
plate
[2])
backward
a
little
CH
~~
“
7
(@).
The
playback
head
(HD1)
and
pinch
roller
Ss
-
OP
also
moves
backward
a
little.
2
6.
The
rotation
of
the
reel
base
(40)
is
high-speeded
m5
by
the
speed
selector
switch
(S4)
(@).
S
7.
Inthe
operation
of
T.ADV,
electricity
is
supplied
\&
ny
to
the
solenoid
(131),
which
attracts
the
arm
°
f
(FR
release
[72]).
The
lock
on
the
arm
(FR
release
[72])
is
released,
FF
is
released
and
FWD
PLAY
is
engaged.
is
@