JVC CD-1770 User manual

MODEL
CD-1770/A/B/C/E
STEREO CASSETTE DECK
No. 4144
May 1976

Contents
Page
Specifications ........ 0.2... ccc ccc 2
F@atu res cannes cese dere: a eta eae aeeeg aeie we ecwree ea Beas 3
Controls and Connections ............0000000e008 3
Main Parts Removing..............2000eeeeeees 4
Enclosure Assembly ..........000cc ce eeeeues 4
Electrical Parts 2.5.02. ic uiweeeke dew en's 6 5
Mechanical Parts ..............0000 cece eeees 6
Main Adjustments ........... 2.00 c eee eee eens 7
Trouble Shooting Guide .............. 00 eee eeee 12
Maintenance .......... 2... cc cece eee eee ees 13
Block Diagram... 0.2... ... ccc eee eens 14
Specifications
Type Stereo cassette deck
Track system 4-track, 2-channel
Cassettes C-30, C-60, C-90
Frequency response :
Signal-to-Noise ratio :
Effect of Super
ANRS
Improvement of
S/N :
Improvement of fre-
quency response :
Imrpovement of
distortion
Wow and flutter
Crosstalk
Harmonic distortion :
Bias z
Chrome *1 20 — 18,000Hz
(Nominal)
30 — 16,000Hz
(Typical)
Regular *2 20 — 17,000Hz
(Nominal)
30 — 15,000Hz
(Typical)
Supasses DIN 45500
*1 TP-18 or Equivalent
*2 QP-12 or Equivalent
56dB(JIS) The S/N is improved by
5dB at 1kHz and by
10dB above 5kHz with
ANRS on
62dB with ANRS
(DIN45500 weighted)
(normal tape)
the same as with ANRS
OVU recording; 6dB at 10kHz
+5VU recording; 12dB at 10kHz
OVU recording; 3% less at 10kHz
0.05% (WRMS)
0.18% (DIN45500)
65dB
1.2% (normal tape)
AC bias (95kHz)
Page
Wiring S622 Hit eta bt aioe Se aie te 15
Standard Schematic Diagram...............20005 16
Circuit Board Parts ............02 cece eee eeeee 18
Main Amp Circuit Board. ........... 0000 cca ee 18
ANRS Circuit Board ...............00000euee 22
Switch Circuit Board .......... 00000 e ences 24
Mechanical Component ..............00000eeeas 26
Enclosure Ass’y and Electrical Parts
except Circuit Board Parts .............0.0000. 32
ACCOSSOFICS 65 a oie cisie-bhe aWewcs ainate o Pree che ates 34
Pack ing 220i esavaretag ates GA ato iis Ge ahs Ae a 35
Erasure AC erasure
Heads Recording/playback
Motor
Tape speed
Recording time
Fast forward time
Rewind time
Semiconductors
Input jacks
Output jacks
Power requirement
Power consumption :
= Sen-Alloy head
Erasure = Ferrite head
Frequency control DC servomotor
4.8cm/sec
2 x 30 minutes with C-60 cassette
75sec with C-60 cassette
75sec with C-60 cassette
6 ICs
40 transistors
2 SCR and 30 diodes
MIC jack x 2
Max. sensitivity 0.2mV
Matching impedance 6002
Input jack x 2
Min, input level 78mV
Input impedance 1002
Output jack x 2
Output level 0~ 0.5V
Output impedance 10k
Matching load impedance 6.8ka
or more
Headphone jack x 1
Output level 0.3mV
Matching impedance 6.8k9 or more
AC 120V, 60Hz (CD-1770/C)
AC 240V, 50Hz (CD-1770A/B)
AC 220V, 50Hz (CD-1770E)
30W
Dimensions Width 16-1/2"' (420mm)
Height 3-1/2’ ( 88mm)
Depth 10-7/8”" (277mm)
Weight 12.1 Ibs (5.5 kg)
Design and specifications are subject to change without notice.
CD-1770/A/B/C/E a ee m
No. 4144

Features
SEN-ALLOY head. Mixing facility.
Built-in ANRS (U.S. Pat. 375 7254 and 376 9612) and Wow flutter show high class mechanism.
Super
ANRS.
Frequency
controlled
servomotor.
Multi-point
peak
level
indicators.
Full
auto-stop.
Timer recording and playback. Tape amount indicator.
Controls and Connections
COS)
@ ©
®
DM OM DDBDAOM ®
Fig. 1
Fig. 2
Left-[L]
1
Left
channel
tevel
meter
[LEFT]
19
MIC-REC
{evel
controls
[MIC/DIN]
(
2:
ht-[R]
2
PEAK
level
indicators
oats
3.
Right
channel
level
meter
[RIGHT]
20
~LINE-REC
level
controls
[LINE]
(
Right-[R]
:
me
indicator
sires
21
Memory
counter
with
reset
button
[COUNTER]
S
indicator
[ANRS]
22
Playback
level
control
6
Super
ANRS
indicator
23.
REC
button
:
ees
aus
rae
24
REW
button
[REW
<<
]
Sheet
25
Playback
button
[PLAY/REC
>
]
We
rece
iit
26
Fast
forward
button
[FF
PP
]
e
Lie.
a
Rica
27.
STOP
button
[STOP
@
]
bes
a
pene
me
28
Pause
button
[PAUSE
4
|
13
Left
channel
microphone
jack
[MIC-L]
29
Right
channel
LINE
OUT
ferninal
:
3
:
30.
~—_
Left
channel
LINE
OUT
terminal
14 ~~ Right channel microphone jack [MIC-R]
15
Headphone
jack
[PHONES]
31.
DIN
socket
[REC/PB]
16
Bena
oe
Si
32
Right
channel
LINE
IN
terminal
ae
33
Left
channel
LINE
IN
terminal
17
ANRS
switch
34
Memory
switch
18
Super
ANRS
switch
z
CD-1770/A/B/C/E
i Rts No. 4144

Main Parts Removing
This
cassette
deck
which
features
a
compact
design
and
high
performance
uses
minuature-sized
parts
which
are
closely
arranged.
Use
special
care
when servicing
it.
Enclosure Assembly
Arrow is shown procedure to
Insert and push remove the cassette lid.
in 4 holes by
small stick. ar
& wer TAC, Cassette *@)
Power switch
knob
Cassette door 1, Press the eject button, then the
cassette door loading upward.
2. Remove the cassette door by pressing
it under side.
Slide volume knobs Pull off it upward.
4Power switch knob
the bracket.
4Eject knob
. Remove the rope on eject knob.
4Select knobs . Remove 2 screws fastening the switch @)
C. board. (EQ & BIAS)
. Remove SW. C. board with it’s
bracket.
. Pull out the select knobs to outer or
inner of the top cabinet.
Remove 6 screws fastening the top cabi-
net, after removing the head cover,
cassette door, botton cover and wood
CD-1770/A/B/C/E
No. 4144 ar oe
e It canbe removed for it’s cleaning
or replacing with other parts un-
removing.
e When replace the cassette door,
insert by pressing it under side,
then one or other side of cassette
door by full locked.
When remove the bottom cover, can
be removed the wood cabinet at as
same.
After removing the bottom cover
only, can be adjusted semi-fixed
resistors (VU meter gain, peak level
and playback gain) on main amp
C. board.
Remove 6 screws fastening the bottom
cover.
When replace the knob, insert knobs
guide plate in score hole of top cabi-
Insert and push in 4 holes near the
power switch by small stick, then can
be removed off the power switch knob.
1. Remove 1 tapping screw fastening
2 earth lugs can be removed as same
the front panel.
cabinet.

Note:
When you remove or replace the cassette lid, be careful not to scratch A position on the front panel.
1. To remove
You have to pull out the cassette lid at direction (2)
pushing down it at direction
scratch on the front panel (A) by your fingers.
2. To replace
@)and controling for not
Fig. 4
At the first, have the cassette lid as same way to
remove. Next, insert holder of it as equal right and left
sides.
At the same time, control for not scratch as same way to
remove, and push in to locking the cassette lid.
(The first push in left side, next, right side.)
not full opening
gv
2 Bae
half opening
2)
When you remove the cassette lid,
open at half mode.
CD-1770/A/B/C/E
No. 4144

Electrical Parts
ANRS C. board
Power switch
Slide volume
Fig. 5
Remove electrical parts after removing the bottom cover.
Main amp Remove 3 tapping screws fastening the
circuit board ass’y main amp circuit board.
ANRS circuit board Remove 2 screws fastening the ANRS Q)
ass’y C. board
Switch circuit board 1. Remove 2 tapping screws fastening Remove switch circuit board ass’y
ass'y the bracket for switch C. board ass’y. after removing the bracket for it.
2. Remove 4 screws fastening the Bias
SW C. board (2 p.c.s) and the EQ SW
C. board (2p.c.s)
©
. Remove 2 screws fastening the trans.
bracket.
2. Remove 2 screws fastening the trans-
former
3. Disconnect it’s wires.
Power transformer
Remove the Mic jacks ass’y after remov-
ing the front panel.
Remove 1 screw fastening the Mic jacks
ass'y.
Mic jacks ass’y
Remove the front panel and the main
amp C. board ass’y.
MIC/DIN level controls..... 4screws
LINE level controls........... 4screws
Playback level control ..... 2screws
Slide level controls
CD-1770/A/B/C/E
No. 4144 GS

Mechanical Parts
Motor circuit board Motor @) @ Motor Capstan belt
tA t
rs it =
= lp
te}
°
fe}
Take up disc
= 0
ce}
ra
©
CSM
i
vi
©
=A
arm ass'y ol
Be careful not to stain the belt.
When replace the motor, replace it’s
circuit board as same time.
Be careful no to stain the belt.
When replace the flywheel, don’t
forget to insert a nylon washer to
it’s shaft.
Fig. 6
Mecha-ass’y Remove the cassette cover, head cover
and bottom cover. @
chassis.
Motor . Remove the take up belt.
. Remove the capstan belt.
. Disconnect 2 wires of motor circuit
board ass’y.
. Remove 3 screws and 3 washers fasten- Q)
ing the motor.
Pinch roller arm assy 1. Remove “E” ring holding the pinch @)
roller arm ass’y.
Take up disc . Remove the counter belt.
. Remove “E” ring holding the take up
disc.
. Pull off the disc from the shaft.
Supply disc 1. Remove “E” ring holding the supply 6)
2. Pull off the disc from the shaft.
Remove 4 screws fastening the macha-
Flywheel . Remove the take up belt.
. Remove the capstan belt.
. Remove 2 screws fastening the fly-
wheel holder.
. Pull off the flywheel.
. Remove spring on the arm ass’y.
disc.
NOTE; Don't dirty, slippery and undue run-out the capstan belt and counter belt.
CD-1770/A/H/C/E
ay a No. 4144

Main Adjustments
Electrical Adjustment
Equipment and measuring instruments used for adjustment. AUDIO Freq. OSC
1.
V.T.V.M.
(measuring
AC
in
millivolt)
N
cas
ATTENUATOR
2. Audio-frequency oscillator | Jeep)
(range: 50—20kHz and output OdB with impedance 60022) ae By aS, i 60002
DVO"
3. Attenuator BOIS:
4. Reference tapes for REC/PB pease
TS-1 (OP-12, C521V) — normal tape by @
TS-2 (TP-18, C401R) — chrome tape ouTPUT LINE IN
5. Reference tapes for playback
VTT-664 (1kHz 16mM)
VTT-666 (400Hz 22mM)
6. Resistors
1002 (for measurement of the bias current)
6002 (for attenuator matching)
INPUT
LINE OUT
Fig. 7
When you adjust following item, we recommend to you to keep doing step No.
CA
1 Level meter . Set the deck in the record mode. (Main amp The angle of meter deflection
Input 1KHz signals (about 10dBs) from C. board has been factory adjusted, but
LINE IN jacks and adjust LINE IN TAA313201) should be adjusted when parts
volume control so that LINE OUT are are replaced.
-8dBs.
3. Adjust semi-fixed resistors R146 and VR103,203 When adjust the level meter,
246 in this condition it obtain zero don’t use a headphone.
VU meter reading.
2 Peak level
. Set as same mode at step(1) and adjust (Main amp
semi-fixed resistor R506 so that the C. board
“0” indicator is lighting and no light- TAA313201)
ing at -1dB from step(1) with atten- R506
uator.
2. Adjust semi-fixed resistor R508 so that
the ‘’-5” indicator is lighting at -5dB
from step(1) with attenuator.
3. Adjust semi-fixed resistor R510 so that
the ““-10” indicator is lighting at -10dB
from step(1) with attenuator and no
lighting at -11dB from step(1) with
attenuator.
4. Adjust semi-fixed resistor R504 so that
the “+3” indicator is lighting at +3dB
from step(1) and no lighting at +2dB
from step(1) with attenuator.
5. Adjust semi-fixed resistor R502 so that
the “+6” indicator is lighting at +5dB
from step(1) with attenuator.
3 Playback . Set equalizer switch at normal and (Main amp . Adjust playback sensitivity
sensitivity playback reference tape VT T-664. C. board) when heads are replaced.
Adjust semi-fixed resistors R115(L) R115,215 2. Make this adjustment after
making sure level meter
deflection angle is correct.
and R215(R) so that level meters indi-
cate zero VU (about 0.3V at LINE
OUT).
2. Playback reference tape VTT-666 and
check that the VU meter indicate CAL.
CD-1770/A/B/C/E
No. 4144 2ghe

4 Bias
current
1. Adjust bias current when
heads or other parts are
replaced.
2. Use the highclass V.T.V.M.
for high frequency re-
sponse.
3. After the bias current
adjustment, check the fre-
quency response at 10kHz
signals.
(Main amp
C. board)
1.
Insert
a
1002
resistor
into
the
ground
side
wiring
of
the
head
and
connect
the
V.T.V.M.
across
the
resistor,
and
set
the
BIAS
SW
at
chrome
or
normal.
First
adjust
for
chrome
tape,
then
for
normal
tape.
2.
After
the
deck
correct
the
head
wires,
input
the
standard
level
of
1kHz
sig-
nals
to
use
reference
tape,
and
measure
REC/PB
frequency
response
at
10kHz.
3. Adjust semi-fixed resistors R604,704
(chrome) 605,705(normal) so that the
10kHz frequency response does be-
chrome
come
+10dBs.
R604
,704
Repeat
the
recording
and
playback
so
normal
that
10kHz
signals
become
correct
fre-
R605,705
quency response.
Level over at 10kHz compared with
1kHz — bias current less
Level less at 10kHz compared with
1kHz — bias current over
5
Recording
1.
Set
the
deck
in
the
record
mode.
(Main
amp
.
This
adjustment
is
necessa-
signal
2.
Input
the
1kHz
(-—10dBs)signals
to
C.
board)
ry
when
heads
are
replaced.
current
LINE
IN
jacks
and
adjust
the
recording
2.
Make
this
adjustment
after
level control so that the VU meters
adjusting steps(1) through
indicate
zero
VU.
(4)
3.
Playback
the
tape,
adjust
the
semi-fixed
chrome
3.
Check
the
frequency
re-
resistors
R606,706(chrome)
R607,707
R606,706
sponse
at
10kHz
after
this
(normal)
so
that
the
VU
meters
indi-
normal
adjustment.
cate
zero
VU.
R607,707
4.
Set
EO
and
BIAS
switches
according to type of tape
used.
R324 ,424
(REC
GAIN)
R338,438
(DC
BIAS)
R325,425
(CONT
GAIN)
R312,412
(PB GAIN)
6
ANRS
.
Disconnect
'‘D”’
connector
of
bias
oscil-
circuit
lator
so
that
oscillator
does
not
operate.
2. Set the deck in the record mode.
3. Input 1kHz —10dBs signals from LINE
IN jacks adjust the recording volume
controls so that the voltage across
LINE OUT is —5dBs.
4. Turn R325 and R425 (CONT GAIN)
and R338 and R438 (DC BIAS) in the
direction opposite to the marking.
5. Adjust R324 and R424 so that level
does not change when ANRS is turned
on and off, and turn on ANRS.
6. Input 1kHz, —50dBs signals from
LINE IN.
Adjust R338 and R438 so that voltage
across LINE OUT is —-39.5dBs.
7. Input 5kHz —30dBs signals from
LINE IN.
Adjust R325 and R425 so that voltage
across LINE OUT is —21.5dBs.
8. Repeat steps(5) through (7).
9. Turn ANRS switch is “Super” position
when input 10kHz -10dBs signals from
LINE IN.
Check output levels are -11dBs +2dB.
10. Connect receptable of bias oscillator
disconnected in step (1).
11. Play reference tape VTT-664 and adjust
R312 and R412 so that level does not
change when ANRS is turned on and off.
CD-1770/A/B/C/E
No. 4144

Mechanical Adjustment and Repairs
a
REC/PB head 1. Turn the adjustment screws ((A)and screws If either of the record/play-
(Azimuth ) so that measure ‘’a” is 3.5mm. back head and the erase head
inclination) 2. Insert screws in the spring and shown low performance be-
unfasten it on the head panel. cause of wear, broken wire of
3. Fasten the screw(D) on the head excessive magnetization, it
panel. should be replaced.
4. Fasten the screw (C). If necessary, adjust playback
5. Turn the adjustment screw(D)so that sensitivity, REC bias current,
the head is horizontal. and bias trap.
6. Playback the test tape C-120 (front (Screw (A) and(B) are head
cutted cassette) and turn the adjust- inclination adjustment.
ment screws ().6) and(D) so that Screw is head azimuth
the test tape move running to no adjustment.
touch the tape guide tip (upper or Screw(C)is fixed.)
under side). If checking is difficult, cut
1)When the test tape uncorrect touch- front upper side (near E head,
ing at upper side of tape guide, REC/PB head and capstan) of
loose the adjustment screws and the cassette C-120 by a cutter
to move the head position at knife, etc, then easy check it.
under side.
2)When the test tape uncorrect touch-
ing at under side of tape guide
fasten the adjustment screws (A)and
(B)to move the head position at
upper side.
7. Insert the cord plug into the LINE
OUT jack (or REC/PB), and connect
the other end of the cord to a
V.T.V.M. (vacuum tube voltmeter}.
8. Play the azimuth adjustment test tape
(e.g. JVC’s VTT-653, 10kHz).
9. Turn the azimuth screw so that
the output will become maximum.
10. If output of left and right channels
unbalance level, turn the adjustment
screws (A) and for correct the head
Position.
1) If output of right_channel less level
loose the screw and fasten the
screw(B).
2) If output of left channel less level,
fasten the screw and loose the
screw(B).
11. After this adjustment, the screw(B)
should be locked with a bond.
head panel
tape guide
—=— (upper side)
tape
tape
tape guide
(under side)
<_
After replacement, adjust the
head height position.
Playback the test tape C-120 (front
cutted cassette), and turn the adjust-
ment screw so that the test tape
move running to no touch the tape
guide tip (up or under side).
1)When the test tape uncorrect touch-
ing, at under side of tape guide, loose
the screw ;
2)When the test tape uncorrect touch-
ing, at under side of tape guide, fasten
screw (F).
Erasing head
(height)
tape guide
~=—(upper side)
tape
tape
el tape guide
(under side)
CD-1770/A/B/C/E
No. 4144 — 10 —

Motor speed
Take-up
torque
Fast forward
torque
Rewinding
torque
Auto-stop
mechanism
Timer record-
ing mechanism
Door brake
Playback reference tape (3000Hz), and
adjust the semi-fixed resistor on the
circuit board of the motor so that it’s
speed in 3000Hz2+2% (2940~ 3060Hz)
- Remove the front panel and adjust
semi-fixed resistor in the hole of top
cabinet (mould) by the screwdriver.
- If don’t remove the front panel, adjust
semi-fixed resistor in the hole of mecha-
chassis (near the bracket of solenoid for
automatic stop.)
Measure by the torque measure cassette
at the playback mode, or by the torque
gaze tool.
Measure as same way at FF mode.
Measure as same way at REW mode.
Loosen 2 screws fastening the solenoid
and move it position for adjustment.
Loosen 2 screws fastening the solenoid
for pause locking plate and adjust the
solenoid position.
Loosen the screw which retains the spring
bracket and vary the angle at which the
bracket is fixed.
Ste
(If not)
1. Clean the idler belt, rubber
rim of idler, and rubber rim
of the right reed disc.
. Replace the idler arm of
tape-up, and spring.
(If not)
1. Clean the capstan belt,
rubber rim of the idler,
motor pulley, rubber rim
of the right reel disc and
rim of the flywheel.
. Replace the belt, idler and
reel disc ass’y etc.
(If not)
1. Clean the capstan belt,
idler, motor pulley rim of
the flywheel, rubber rim of
the rewinding idler, and
rubber rim of the left reel
disc.
. Replace the reel disc.
Check if the locking and slid-
ing parts of the operation
button cam are well coated
with molybdenum.
. Apply a small quantity of
silicon grease to the inside
surface of the brake pipe.
(SHIN ETSU KAGAKU
KS-64 or equivalent)
. Replace brake pipe or
rubber O-ring.
CD-1770/A/B/C/E
No. 4144

Trouble Shooting Guide
[ELECTRICAL CIRCUIT]
1. Playback tone quality is poor.
1, Check the record/playback head for dust.
2. Check the record/playback head for wear.
If worn excessively, the loss of treble response will
result.
3. Check wiring for a short-circuit.
Check each transistor for condition.
2. Recording tone quality is poor.
The playback tone quality of a recorded tape such as the
audition tape is good, but the recording by this unit
produces poor tone quality. !n this case, the unit should
be checked in the following manner.
1. By monitoring a music while recording, check the
tone quality.
Capstan and
flywheel
Pinch roller
Flywheel turns heavily.
Rough rotation (Deformation
scratches, or dust).
The angular position of the pinch
roller is not correct.
Back tension is irregular, or back
tension is too strong.
CD-1770/A/B/C/E
No. 4144
a
Capstan shaft has excessive run-out.
(shaft seisure, thrust play, etc.)
The pinch roller pressure is not correct.
Belt Belt has undue run-out. Clean the belt or remove the distortion.
Belt is dirty or slippery. Replace the belt.
Motor Motor shaft has undue run-out. Replace motor.
Motor pulley is oily and dusty. Clean motor pulley.
Take-up idler arm Pulley has deflection.
Pulley is stuck.
2. If found poor, check the wiring of the recording
system for a broken wire and short-circuit.
3. If no irregularity is found, check the recording bias
current. Also check the oscillation circuit.
3. For other failures, check the unit in the same manner as
other amplifiers.
[MECHANISM SECTION] (wow and flutter)
If wow and flutter increase, check the following points.
If there is defect in revolving parts, the wow and flutter
generated will increase in proportion to the number of
revolutions.
Play a 3000Hz test tape, and defective part can be detected
from the sound.
Replace flywheel.
Clean the capstan shaft and the groove in the
flywheel.
Apply oil to the metal position.
Replace the capstan assembly.
Replace pinch roller, or pinch roller spring.
Clean the pinch roller or apply oi! to the rotary
shaft.
Adjust the pinch roller so that it is parallel with
the capstan shaft.
Adjust the pinch roller spring.
Replace supply disc, or felt.
Replace back tension spring (under supply disc),
or apply silicon grease.
Replace take-up idler arm.

Maintenance
To get long, trouble-free service, maintenance is important.
Do not forget cleaning and demagnetizing.
Cleaning
After long use, the heads and tape part — capstan, pinch
roller, etc. — will become dirty with dust or magnetic
particles. Dirty heads cause imperfect erasing or high
frequency drop-off. A dirty capstan and pinch roller will
cause unstable tape speed, leading to increased wow and
flutter.
Always keep them clean by following the procedure below.
1. Heads
1) Press the EJECT button with the POWER switch
OFF to open the cassette door.
2) Remove the headcover upward.
3) Press the PLAY button to move the heads out.
4) Use the head cleaning stick provided to wipe the
surface where the tape comes into contact with the
head.
(It is effective to moisten the cotton with alcohol.)
ee |
Pinch roller
Erase head
Recording/playback head ©
Fig. 9
~13—
2. Pinch roller and capstan
1) Press the EJECT button with the POWER switch ON
to open the cassette door.
2) Press the PLAY button, and the pinch roller will
move out and rotate.
3) Apply a soft cloth (soaked in alcohol, it will be more
effective) to the rotating pinch roller and capstan.
Be careful not to let the cloth get caught!
* Do not use any cleaner besides alcohol or a
specifically prepared tape head cleaning solution.
/
Mee ea Sy
Soft cloth eo
Direction of rotation
Vv }
Pinch roller a of pinch roller
3. Cabinet
When the cabinet becomes dirty, wipe it with a soft
cloth soaked with a neutral cleaning solution of a
polishing cloth.
* Do not use thinner or benzine.
Demagnetizing
The heads are made from a material resistant to
magnetization, but after long use they may become
magnetized. A magnet brought into their vicinity can
magnetize the heads, causing excess noise. If noise seems to
have increased, demagnetize the heads with a head
demagnetizer through the following procedure.
1. Turn the POWER switch OFF.
2. Wrap the tip of the demagnetizer with vinyl! tape or soft
cloth so as not to damage the head surface. Switch on
the demagnetizer and bring it close to the head.
3. Move the tip of the demagnetizer slowly first to the left
and right, then up and down in front of the head.
Gradually move it away from the head and switch it off
at a distance of more than 30cm. (12’)
4. The erase head need not be demagnetized. The capstan
shaft and tape guide should be demagnetized in the same
way as the record/playback head.
* Do not bring a magnetized metallic object (a
screwdriver, for example) near the head as this will
increase noise.
CD-1770/A/B/C/E
No. 4144

Block Diagram
Recording system
LINE iN
X104
28C1327
LINE Volume TU
28C828
MIC Jack X101
2SA721
Tu
x102
2SC1327
TU
REC/PB Socket
{DIN}
MIC Volume
R-CH
MIC IN
REC Gain Adj
RCH
OUT
LCH
OuT
ANRS Control
Amp. Gain Adj
301
2SC828
RS
ANRS
Filter
2SA721
TU
2SC1327
TU
ANRS Circuit
Playback system
Playback
Gain Adj
Playback Head
x101
2SA721
TU
X102
25€1327
TU
X104
2SC1327
Tu
x105
2SC828
RS
Equalizer Circust
Chrome
X103
2SC828
proto tron -
ANRS Playtrack Gain Adj
Equahzer Switch dy
'C301
TA7140
ANRS Switch
X301
2SC828
ANRS
Filter
X303
2SA721
TU
X304
28C1327
TU
X302
2SD545VS
To peak level circuit
X108
2SC828
RS
VU meter
Meter Gain Adj
Headphone
Bias OSC Circuit
x801
2SC828
LINE OUT
Bias Adj
Bias Switch
REC Head
x601
2SC828
ARS |
Chrome
Normat
PB
To peak level circuit
VU meter
X108
2SC828
RS
1€101
TA?140
PB
Gain Adj
X106
28C828
ARS
PB Votume
Headphone
LINE OUT
REC'PB Socket
ANRS Control
Amp. Gain Adj
|
i
I
DC Bias Adj |
1C301 '
TA7140
PB |
|
J
i
J
ANRS Circuit
CD-1770/A/B/C/E
No. 4144
rrr
nn
ee
ee
Fig. 12
4a

CD-1770/C
Pounter Memory Switch Switch
Kacy i f Earth is
@&
PIN | ©
DIN jJacks ©
-— VU Meter
R ie
? Peak Level Indicator Circuit Board =e
een
O (|
Peame FY o 2
REIIIE
ANRS Circuit Board
Equalizer... Switch...Circuit..Board
Lt)
oe Head Headphone Jack ®
7
oN rs |
@
&
4
Lamp ©
1 O-
7
|
Bias Switch Circuit Board : “|
if i rr v
Solenoid
Solenoid
Pause Switch
Y
Muting Switch
To MECH Ass’y Earth A Lug
Fig. 13
-—- 15 -—
CD-1770A/B/E
Power Cord 2
Power
Transformer
aa
: \ Ka,
Color code are shown below
Vlas Brown
D-_ Sesesetive Red
Bi sit cevs Orange
ee Yellow
Be sstheatats Green
Osh eit Blue
yee Violet
8 stadiiee. Grey
Q) es covetss White
Om Seseeese Black
CD-1770/A/B/C/E
No. 4144

Standard Schematic Diagram epasole
Xi01
x02
x/03
x104
X105
1c
101
X/07
X106
506
X50!
~
X505
C501
—
—2oATeITY
__
25C13271U_
_2SC828RS_
_25CI327TU_2SC82ORS_TATIG0P-B_Z5CI3BIR3
_ZSCBCBARS____2
—rosa04ap
_
L-CH
LINE
IN
©)
[sors
101-2
5101-3
7
od
s001-4
5101-5
901-6
3101-7
IDS404F
“irs
alii
5B
c
BT
a
ee
~~
a
L-CH LINE
OUT
=
=
~
I-E-#
!
|
|
|
|
|
|
|
I
|
!
!
i
Riza
82K
I
Riz)
68k
]
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fo
mm
ae
me
me
ee
a
of]
c
C-2
|
|
7 | |
| St a : dt | |
E
PBVOL
r-Chp@eter
Adj.
_
+|
Muting
Sw
|
M.P.LC
l
C906 ; . 0 (4) | (4) PI, Board
a7e
PB
Gain
Adj.
HEAD
O
Indicator
|
©
PHONE
a
VU
METER
C.
Boara
|
D50!
D50zZ
0503
D504
505
|
|
LINE MIC 5x van lT | Xsol era ch Se a : T Séaes +3489 ods 5dbs odes w }
Vol
>
Mak.
:
25C82BARS
X3
X4
an
IR
Car
2
Oe
a
esnsesans
zscezers
1
te!
|
||
$608-1
s60a-2
[|
so00-z
3607-1
5606-1
5605-1
s6os-z
I
S601-3
$60/-z
5601-1
S60z-1]
S604-1
Bias
C.
Board
7
Auto
Stop___>
(o>
Pose
|
tw
l
a
|
°
9|
Bo
Taazi33I2
XI
x2
mu
|
ore
I
|
t
"cone
I
2SCB2BRS
25C828RS
>»
ai
|
rs
OP 3
AG
oy
g
SR
ie
ter
wees
eee
l
| = y
ise
‘+d
|
1
|
|
1S
|
EQ. C. Board | Li 1© ae coos a7op + I |
TAABIS3I2
R06
6074
J/
C603
500
3
gor
ESE,
| |
|
Sov
3.3mH
i
|
SA ee ee eee i
RA
|
f
Bias
Adj.
!
Lane
se
OO
Ree
Gain
At
—
ae
a
ar
PN
cial
7]
Sl01-1~
9,
201-1~9
REC/PB
Sw.AT
“PB
robe
kee
I
babe
i
|
|
5301-1
~
4,
gol-1~4
i
(in
ANRS)
Indicator
|
I
f
|
S60/-1
~
3,
701-1
ANRS
SW
AT“ANRS
OFF”
vs
|
|
i
et
Ee
|
seoz-1,
702-1
BIAS
NORMAL
SW
AT”
OFF”
2SCII6ZWT(
BO)
|
|
f
a
100
|
seoa-1,
709-1
BIAS
CHROME
SW
AT
“OFF”
enaraas
|
150P
”
-
|
TANR$
Control
Amp.
Gain
Adf:
wR
|
9605-1 ~Z,
705-1
SUPER
ANRS
SW
AT
“OFF
|
_
|
CD-1770A/B/E
|
=
>
t
5606-1
~
2,
706-1~Z
EQ
NORMAL
SW
AT“
OFF”
|
J
Cc. A
|
3.5m
ev
BRE
oe
Rese
zae|
[AE
Te
S$607-1,
707-1
E@
SA
SW
AT
“OFF”
ee
ee
ee
H
|
a0
fan°
fone)
>
338
|
—_
DG)
cee
See!
||)
iy
Pe
eg
a
ee
Al
TOK
78S
C310
ov
$608-/~2,
708-1
E@
CHROME
SW
AT
“OFF
A
Joe
|
Rit
ik
cae
oy.
«L301
:
|
;
l
on
|
pend
e312)
4.7
Te)
|
Ct
oezeur
‘
ees
|
6
pz02
|
5!
POWER
SW
AT
“POWER
org”
4
‘ext!
|
em
y
.|
|
32
PAUSE
SW
AT
“PAUSE
OFF”
|
:
a
oe
“nee,
vane
ee
ere
|
|
$3
MOTOR
Sw
AT
MOTOR
OFF”
I
:
z
aad
aS
aed
|
|
$4
MUTING
SW
AT
“MUTING
OFF”
|
od
deco
a
ee
lrso’
|
35
MEMORY
SW
AT“OFF”
=
|
|
Hii,
a
Oh
|
Se
ee
\'*
heed
|
56
REWIND
sw
‘
|
=
oxo
done
9
power
l
|
S7
COUNTER
SW
,
+o
ruse
>
a
=
POWER
SW
|
=
Power Cord — fae re
ane
EE
sR
RS
a
NOL
eRe
OS
a
PE
LE,
AT
eee
ves
1
A
x30!
X302'
X303
X
304.
X305
IC
301
Ne
wa
es
ee
2SC828RS = SSD545NR-VS 2SAT2ITU 2SC1327TU 25CBCBRS TATI40P-B
ANRS
PB
Gain
Adj.
ANRS
Rec.
Gain
Adj.
ANRS
DC
Bias
Adj.
Fig. 14
CD-1770/A/B/C/E

VARIABLE RESISTORS
R115,215
R148 ,248
R146,246
R147 ,247
R149,249
R604,704
R605,705
R606,706
R607 ,707
R312,412
R323,413
R325 ,425
R338,438
R502,504,
506,508,
510
TRANSISTORS
X101,201
X102,202
X103,203
X104,204
X105,205
X106,206
X107,207
X108,208
X501~ 505
X506
X601,701
x801
X301,401
X302,402
X303,403
X304,404
X305,405
ICs
1C101,201
1C501
1C301,401
PLAYBACK GAIN ADJ. 50k2
PLAYBACK VOLUME CONTROL 10k (A)
METER GAIN ADJ. 2ka
LINE REC VOLUME CONTROL 100k2 (A)
MIC/DIN REC VOLUME CONTROL 50k2
BIAS CURRENT ADJ. (CHROME) 100ka2
” (NORMAL) 100k2
REC GAIN ADJ. (NORMAL) 50k2Q
” (CHROME) 50k2
ANRS PLAYBACK GAIN ADJ. 5ka
ANRS REC GAIN ADJ. 5kaQ
ANRS CONTROL AMP GAIN ADJ. 20kaQ
ANRS DC BIAS ADJ. 1ka
PEAK LEVEL ADJ. 500k2
2SA721TU
2SC1327TU
2SC828RS
penta MAIN AMP CIRCUIT
2SC828ARS
2SC828RS
2SC828RS
2SC828S PEAK LEVEL CIRCUIT
2SA564ARS
2SC828ARS EQUALIZER SW CIRCUIT
2SC828ARS BIAS SW CIRCUIT
2SC828RS
2SD545VS
2SA721TU ANRS CIRCUIT
28C1327TU
2SC828RS
2SC828RS
2SC828RS
2SA564ARS POWER SUPPLY CIRCUIT
2SC828RS
2SC1162WT (BC)
TA7140P-B MAIN AMP CIRCUIT
TD3404AP PEAK LEVEL CIRCUIT
TA7140P-B ANRS CIRCUIT
Transistor IC TA140P-BC
B (Base)
a— C (Collector)
E (Emitter)
1234567
Fig. 15
—~17-—
DIODES
D501~505
D506~508
D301,302,
401,402
D303,403
D101~ 104,
201~204
D1,2
D3
D4
D5
D6~ 13,16
D509
SWITCHES
$101-1~9,
201-1~9,
301-1~4,
401-1~4
$601-1~3,
701-1
$602-1,702-1
$604-1,704-1
$605-1~2,
705-1
$606-1~2,
706-1~2
$607-1,707-1
TLR102 LED
(Light Emitted Diode)
... PEAK LEVEL INDICATOR
TLR105 LED
REC, ANRS, Super ANRS
INDICATOR
OA90 GE. DIODE
.... ANRS CIRCUIT
VD1212 SI. DIODE VARISTOR
we ANRS CIRCUIT
OA90 GE. DIODE
ww PEAK LEVEL CIRCUIT
GE. DIODE
POWER SUPPLY CIRCUIT
GE. DIODE
sis POWER SUPPLY CIRCUIT
1N4733T5 ZENER DIODE
aes POWER SUPPLY CIRCUIT
RD24E(1) ZENER DIODE
a POWER SUPPLY CIRCUIT
T30155-001 or VO6-B GE. DIODE
tke POWER SUPPLY CIRCUIT
RD4.3EC ZENER DIODE
es MAIN AMP CIRCUIT
REC/PB SWITCH AT “PB"’ MODE
ANRS SWITCH AT “ANRS OFF”
BIAS NORMAL SWITCH AT “OFF”
BIAS CHROME SWITCH AT “OFF”
SUPER ANRS SWITCH AT “OFF”
EQ CHROME SWITCH AT “OFF”
EQ SF SWITCH AT “OFF”
EQ CHROME SWITCH AT ‘‘OFF”
POWER SW AT “POWER OFF”
PAUSE SW AT “PAUSE OFF”
MOTOR SW AT “MOTOR OFF”
MUTING SW AT “MUTING OFF”
MEMORY SW AT “OFF”
REWIND SW
COUNTER SW
IC TD3404AP
14131211109 8
It
1234567
CD-1770/A/B/C/E
No. 4144

Circuit Board Parts
Main Amp Circuit Board — Red print is shown the voltage (V) of playback mode.
( ) voltage; at recording mode.
When you measure the voltage by tester, we recommend
you to use 20k2/V or more impedance tester.
— 1 Pays
AAR ose
— ‘lea _ Se) ce ~
wh
GAUDI TL
p-a eu RS ee
Se Neo ke:
4
« Adjust semi-fixed resistors by parts side.
Meter Gain Adj.
CD-1770/A/B/C/E
No. 4144 es

Main Amp Circuit Board Parts List
* TAA313201-01
(Peak & Meter Circuit)
R511,512,513,514,
515
R501
R503
R505
R507
R509
C126,127,226,227,
501
C128,228
R502,504,506,508,
510
R146,246
D103,203,104,204,
101,201,102,202
X501,502,503,504,
QRD142K-331
-334
n 394
» 474
» 564
» 684
QEW41EA-105
QEW41CA-106
OVP8A0B-055
”
OAS90
2SC828S
TD3404AP
QRD143K-221
QRD146K-561
ORD143K-152
QRD143K-272
ORD142K-104
OQRD143K-184
QRD146K-470
QRD121K-391
OQRGO16J-101
» -102
ORGO26J-151
TAZ000331-02
OMF51AZ-R50
0” -R315
QEW40JA-477
QEW41AA-107
" 477
QEW41CA-336
" -476
0” -107
-108
QEW41EA-227
QEW41VA-107
" 477
ORD143K-561
2SA564ARS
2SC828RS
2SC1162WT(BC)
2SF656
RD24E-(1)
1N4733T5
C. Board
C. Resistor
E. Capacitor
V. Resistor
Ge. Diode
Si. Transistor
IC
C. Resistor
O.M.F. Resistor
Fuse Holder
Fuse
E. Capacitor
C. Resistor
Si. Transistor
”
SCR
Zener Diode
”
—~19 —
2202
5602
1.5kQ
2.7k2
5.6k2
8.2ka
10kQ
22k2
39k2
100kQ
180k2
472
3902
1002
1ka2
1502
CD-1770A/E
470uF
100uF
470uF
33uF
47 uF
100 F
1000, F
220uF
100uF
470nF
5602
1
2
3
1
1
1
6
3
1
1
1
1
1
1
1
1
6
2
1
2
1
1
2
2
1
1
2
1
2
1
1
3
1
2
1
1
CD-1770/A/B/C/E
No. 4144

D6,7,8,9,10,11,12
13,16
(Main Amp Circuit)
R133
R518
R143,243
R108,208
R117,217
R127,227,516
R128,228
R129,229
R126,226
R116,216
R130,230
R131,231
R137,237
R124,141,224,241
R112,212
R139,140,239,240
R103,125,203,225
R519,132,135,232,
235,233
R136,236
R138,238,137,237
R109,209,141,241
R107,113,123,207,
213,223,111,211
R517
R114,142,214,242
R106,119,206,219
R121,221,122,222
R105,110,205,210
R134 ,234
R120,220
R104 ,204
R118,218
R144 145,244,245
C106,206
C109 209
C121,221
C111,116,122,123,
125,211,216,222,
223,225
C117,217
C120,220,502
C124 ,224
C115,119,215,219
C110,113,210,213
C108 208
C107,207
C112,212
C118,218
C114,214
C104,105,204,205
CD-1770/A/B/C/E
T30155-001
or V06-B
LPSP3006ZS
TAR272448-01
ORD143K-472
QRD142K-220
” -560
" -181
” -221
QRD143K-333
QRD142K-820
QRD146K-271
QRD142K-331
” -391
OQRD146K-821
QRD142K-221
” -222
-152
”
QRZ0019-124
QRD142K-224
823
QRZO0019-564
QRD142K-105
QRD122K-391
QEW41AA-107
QEW41CA-336
" -107
QEW41EA-475
-105
-106
-336
" -107
QEB41EM-475
" 476
QEE41EM-335
QFM41HK-184
" 472
QCS11HJ-151
QCS11HK-101
Ge. Diode
”
Si. Diode
Screw
Heat Sink
C. Resistor
L.L.E. Capacitor
T.S.E. Capacitor
Mylar Capacitor
”
Fixed C. Capacitor
"
=90" =
or BRD DMDPANANNNNNNNWNHNDND = =
SNNNAENNNNAAAARS _
PBPNHNNNN A AN WD