JVC TDW-271 Service manual
MB061200312
SERVICE MANUAL
DOUBLE CASSETTE DECK
TD-W271
AUTO REVERSE
A
3MOTOR SILENT MECHANISM
PLAYBACK
POWER
STANDBY/ON ON OFF
DOUBLE CASSETTE DECK
REVERSE MODE
DOLBY NR
B OFF C
STANDBY
COUNTER RESET
PLAY
PHONES
INPUT LEVEL
5
46
37
28
19
MIN MAX
COUNTER RESET
AUTO TAPE SELECTOR / CONTINUOUS PLAY
PLAY
REC / REC MUTE PAUSE
AUTO REVERSE
3MOTOR SILENT MECHANISM
DOLBY B-C NR HX PRO
B
REC/PLAYBACK
A B SYNCHRO DUBBING
NORM SPEED
HIGH SPEED
Area Suffix
UF -------------- China
U -------- Other Areas
TABLE OF CONTENTS
1 PRECAUTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
2 SPECIFIC SERVICE INSTRUCTIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
3 DISASSEMBLY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5
4 ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-13
5 TROUBLESHOOTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-19
SPECIFICATION
Type Double cassette deck
Track system 4-track, 2-channel
Tape speed 4.8 cm/sec (1-7/8 inch/sec) (Normal)
9.5 cm/sec (3-3/4 inch/sec) (High)
Frequency response
(-20 dB recording)
S/N ratio 58 dB (S = 315 Hz, k3 = 3%, N = A-weighted, Type IV tape)
Improvement of MOL 4 dB at 10 kHz with Dolby C NR on.
Wow and flutter 0.08% (WRMS), ±0.2% (DIN/IEC)
Channel separation 10 dB (1 kHz)
Crosstalk 60 dB (1 kHz)
Harmonic distortion k3; 0.8% (Type IV tape, 315 Hz, 0 VU)
Heads Deck A METAPARM head for playback × 1
Motors Electric govemed DC motor for capstan × 1
Fast forward/rewind time Approx. 110 sec. with C-60 cassette
Input terminals LINE IN (× 1 circuit) Input sensitivity 80 mV (0 VU)
Output terminals LINE OUT (× 1 circuit) Output level 300 mV (0 VU)
Other terminals COMPU LINK-3/SYNCRO × 2
Power requirement AC 220 V, 50 Hz
Power consumption With power on 17 W
Dimensions 435 × 139 331 mm
Mass 5.0 kg
Type IV tape 20-17000Hz
30-16000 Hz (±3dB)
Type II tape 20-16000 Hz
30-15000 Hz (±3dB)
Type I tape 20-16000 Hz
30-15000 Hz (±3dB)
The S/N is improved by about 15 dB at 500 Hz and by max.
20 dB at 1kHz ~ 10 kHz with Dolby C NR on and improved by 5 dB
at 1 kHz and by 10 dB at above 5 k Hz with DOLBY B BR on.
Deck B METAPARM head for recording/playback,
2-gap ferrite head for erasure; combination head × 1
DC motor for reel × 1
DC motor for mechanism drive × 1 (For both decks A and B)
Input impeadance 50 kΩ
Output impeadance 5 kΩ
PHONES × 1 Output level 0.3 mW/8 Ω(0 VU)
Matching impedance 8 Ω - 1 k Ω
With power standby 4.0 W
Design and specifications are subject to change without notice.
1-2 (No.MB061)
SECTION 1
PRECAUTION
1.1 Safety Precautions
(1) This design of th is product contains special hardware and
many circuits and components specially for safety purposes. For continued protection, no changes should be made
to the original design unless authorized in writing by the
manufacturer. Replacement parts must be identical to
those used in the original circuits. Services should be performed by qualified personnel only.
(2) Alterations of the design or circuitry of the product should
not be made. Any design alterations of the product should
not be made. Any design alterations or additions will void
the manufacturers warranty and will further relieve the
manufacture of responsibility for personal injury or property
damage resulting therefrom.
(3) Many electrical and mechanical parts in the products have
special safety-related characteristics. These characteristics are often not evident from visual inspection nor can the
protection afforded by them necessarily be obtained by using replacement components rated for higher voltage, wattage, etc. Replacement parts which have these special
safety characteristics are identified in the Parts List of Service Manual. Electrical components having such features
are identified by shading on the schematics and by ( ) on
the Parts List in the Service Manual. The use of a substitute
replacement which does not have the same safety characteristics as the recommended replacement parts shown in
the Parts List of Service Manual may create shock, fire, or
other hazards.
(4) The leads in the products are routed and dressed with ties,
clamps, tubings, barriers and the like to be separated from
live parts, high temperature parts, moving parts and/or
sharp edges for the prevention of electric shock and fire
hazard. When service is required, the original lead routing
and dress should be observed, and it should be confirmed
that they have been returned to normal, after reassembling.
(5) Leakage shock hazard testing
After reassembling the product, always perform an isolation check on the exposed metal parts of the product (antenna terminals, knobs, metal cabinet, screw heads,
headphone jack, control shafts, etc.) to be sure the product
is safe to operate without danger of electrical shock.Do not
use a line isolation transformer during this check.
• P lug the AC line cord directly into the AC outlet. Using a
"Leakage Current Tester", measure the leakage current
from each exposed metal parts of the cabinet, particularly any exposed metal part having a return path to the
chassis, to a known good earth ground. Any leakage current must not exceed 0.5mA AC (r.m.s.).
• Alternate check method
Plug the AC line cord directly into the AC outlet. Use an
AC voltmeter having, 1,000Ω per volt or more sensitivity
in the following manner. Connect a 1,500Ω 10W resistor
paralleled by a 0.15µF AC-type capacitor between an exposed metal part and a known good earth ground.
Measure the AC voltage across the resistor with the AC
voltmeter.
Move the resistor connection to each exposed metal
part, particularly any exposed metal part having a return
path to the chassis, and measure the AC voltage across
the resistor. Now, reverse the plug in the AC outlet and
repeat each measurement. Voltage measured any must
not exceed 0.75 V AC (r.m.s.). This corresponds to 0.5
mA AC (r.m.s.).
AC VOLTMETER
(Having 1000
ohms/volts,
or more sensitivity)
0.15 F AC TYPE
Place this
probe on
1500 10W
Good earth ground
1.2 Warning
(1) This equipment has been designed and manufactured to
meet international safety standards.
(2) It is the legal resp onsibility of the repairer to ensure that
these safety standards are maintained.
(3) Repairs must be made in accordance with the relevant
safety standards.
(4) It is essential that safety critical compone nts are replaced
by approved parts.
(5) If mains voltage selector is provided, check setting for local
voltage.
1.3 Caution Burrs formed during molding may be left over on some parts
of the chassis.
Therefore, pay attention to such burrs in the case of preforming repair of this system.
1.4 Critical parts for safety
In regard with component parts appearing on the silk-screen
printed side (parts side) of the PWB diagrams, the parts that are
printed over with black such as the resistor ( ), diode ( )
and ICP ( ) or identified by the " " mark nearby are critical
for safety. When replacing them, be sure to use the parts of the
same type and rating as specified by the manufacturer.
(This regulation dose not Except the J and C version)
each exposed
metal part.
(No.MB061)1-3
SECTION 2
SPECIFIC SERVICE INSTRUCTIONS
This service manual does not describe SPECIFIC SERVICE INSTRUCTIONS.
1-4 (No.MB061)
SECTION 3
DISASSEMBLY
3.1 Enclosure section
3.1.1 Removing the top cover
(See Fig.1)
(1) Remove four screws A retaining the top cover from both
side.
(2) Remove two screws B retaining the top cover from the
back side.
(3) To remove the top cover, slide in direction of arrow and lift
away (refer to Fig.1).
Top cover
A
B
3.1.2 Removing the front panel assembly
(See Fig.2, 3)
(1) Remove the top cover as described in above.
(2) Remove the three screws C retaining the front panel as-
sembly from bottom side.
(3) Release the front panel assembly from two pawls in the
front and bottom sides and draw it to the front side.
(4) Disconnect all connectors between the mechanism assem-
bly, front panel assembly and main board.
A
C
Fig.1
Front panel assembly
Pawl
C C
Fig.2
M
B
Pawl
Pull 2
Push 1
Push up with a screwdriver, etc. 1
Pull 2
Fig.3
(No.MB061)1-5
3.1.3 Removing the mechanism assembly
• Although the mechanism assembly can be removed without
detaching the front panel assembly, it is recommended to detach the front panel assembly to do the work with ease.
(1) Remove the two screws D or two screws E from the cor-
ners of the mechanism. (Fig.6)
(2) Open the door and remove the mechanism assembly.
(At this time, door lock arm spring and door lock arm are removed together with.)
(3) For moving the mechanism assembly only, disconnect the
following wirings.
a) Mechanism assembly side (Fig.5)
Top side connector of the cam switch board (CN2
).
Connector of the motor board (CN1). (Board to board
connector)
b) Main board side (Fig.4)
Disconnects CN802
from switch/volume board and CN861 from
CN801
from mecha control board,
headphone jack board.
Disconnect wire coming from the head mount assembly CN811
at deck A and CN815 at deck B.
Remove one screw F and remove one GND wire
from mechanism control board.
3.1.4 Removing the eject arm assembly
(Fig.6)
(1) Remove the screws G retaining the eject arm assembly
and pull it out.
DECK A
Motor
board
Main board
F
From Mechanism
control board
CN802
From DECK A
CN861
CN811
Mechanism control board
Mechanism
control
board
Cam
switch
board
CN801
Fig.4
L
From Headphone jack
board
From Switch/
Volume board
CN815
From DECK B
Mechanism
control
board
DECK B
Motor
board
Cam
switch
board
Motor
board
Mechanism control board
Motor
board
DECK B DECK A
Cam switch board
Cam switch board
Fig.5
DDGGE E
DECK B DECK A
Fig.6
1-6 (No.MB061)
3.1.5 Removing the mechanism holder and door assembly
(Fig.7, 8)
(1) Remove four screws H retaining the mechanism holder.
(2) Remove the damper assembly (for easy reassembling
work).
Insert an originary (-) screwdriver or the like in to the gap
between the damper and the front panel to disengage the
pawl, and draw the damper assembly outwards. (See
Fig.7)
(3) Remove the arm shaft of the cassette holder (door assem-
bly) from the mechanism holder. (The door spring is engaged with the door side by the longer side.) (See Fig.8)
(4) Remove the eject spring from lock lever and mechanism
assembly. (See Fig.8)
How to remove damper
Pawl
Fig.7
How to engage the door and eject spring
Lock lever
Cassette door
Longer side
door spring
Shorter side
eject spring
Mechanism assembly
Fig.8
(No.MB061)1-7
3.1.6 Removing the switch & volume board
(Fig.9)
(1) After removing the mechanism hold er, proceed to the fol-
lowing steps.
(2) Pull out the INPUT volume knob.
(3) Remove four screws J, one screw N and cap retaining the
switch/volume board.
(4) Lift the board right upwards to remove it since it is connect-
ed to the key switch board with connector pins (CN603
).
CN604
(5) Disconnect CN602 coming from Mechanism control board
(CN702
).
3.1.7 Removing the headphone jack board
(Fig.9)
(1) After removing the switch/volume board, pull the head-
phone jack board outwards while pushing it down toward
the bottom side to remove it.
3.1.8 Removing the key switch board
(Fig.9)
(1) Remove one screw K (Deck A or B) retaining the board.
(2) Do the same for the other side.
3.1.9 Removing the main board
(see Fig.4 and 1)
(1) Remove three screws L retaining the board.
(2) Remove four screws M retaining the board to the rear pan-
el.
3.1.10 Reassembling procedure of the front panel assembly
(1) Attach the key switch board to the panel with two screws.
(2) Attach the mechanism holder to the front panel assembly
with four screws.
(3) Put the door assembly on the front panel.
(4) Engage the door spring properly.
(5) Install the damper. (Push the pawl side last to engage it.)
(6) Install the mechanism assembly.
(7) Attach the mechanism control bo ard to the panel with two
screws.
(8) Install the eject arm assembly.
(9) Attach the switch/volume board to the panel with five
screws.
(10) Hook the eject spring between lock lever and mechanism
assembly.
Mechanism control board
N
CN702
/
CN604
Key switch board
CN602
CN603
J
JH HKHKH J
Key witch board
Cap
Headphone jack board
Switch/Volume board
Key switch board
Fig.9
1-8 (No.MB061)
3.2 Cassette mechanism section
r
r
3.2.1 Removing the head mount assembly
(Fig.10 and 11)
(1) Remove the FPC holder from the me chani sm frame in the
direction indicated by the arrow (A).
(2) Remove three screws A retaining the he ad mo unt assem-
bly.
3.2.2 Removing the pinch roller assembly
(Fig.10 and 12)
(1) Remove the pinch roller an d pinch roller spring, refer to
Fig.12.
Mechanism A
Pinch roller (left) Pinch roller (right)
Head mount assembly
Fig.10
A
Head mount assembly
Head base
(A)
FPC Holder
Fig.11
Pinch roller
(left)
Pinch roller
spring
Pawl
Pinch rolle
(right)
Pinch rolle
spring
Pawl
Fig.12
(No.MB061)1-9
3.2.3 Removing the FM bracket/Capstan motor assembly
(Mechanism A and B)
(1) Remove soldering of connector FM on reel motor board.
(Fig.13)
(2) Remove three screws B and disengage two pawls, and
then the FM bracket and the capstan belt can be removed.
(Fig.13 and 14)
(3) Remove two screws C retaining the capstan motor from the
FM bracket. (Fig.13)
(4) For reengaging the capsta n belt, refer to Fig.14.
Reel motor board
Pawl
Connector FM
FM bracket
B
Fig.13
Capstan motor
B
C
Pawl
B
Capstan belt
3.2.4 Removing the flywheel assembly
(Fig.15)
(1) Remove two screws D and remove the shield plate.
(2) Pull up the flywheel (L) and (R), and remove them.
3.2.5 Removing the reel motor board
(Fig.15)
(1) Remove four solde ring of the reel motor and actuator mo-
tor, and remove the reel motor board.
Actuator motor
Soldering
Reel motor
Flywheel (R)
Fig.14
Shield plate
D
Fig.15
Soldering
Reel motor board
Flywheel (L)
1-10 (No.MB061)
3.2.6 Removing the reel motor assembly
A
(Fig.16)
(1) Remove two screws E from rear of chassis and remove the
reel motor assembly toward upward.
3.2.7 Removing the actuator motor assembly
(Fig.16)
(1) Remove two screws F from rear of chassis and remove the
actuator motor assembly toward upward.
3.2.8 Removing the mechanism board
(Fig.17)
(1) Remove one screw G retaining the board.
(2) Release the mechanism bo ard from five pawls.
(3) For gearing between the mechanism board and control
cam, see the magnified illustration in a circle.
ctuator motor assembly
Reel motor assembly
Mechanism board
EF
Fig.16
Mechanism board
Pawl
Pawl
G
Fig.17
(No.MB061)1-11
3.2.9 Removing the control cam
(Fig.18 and 19)
(1) Release the control cam from two pawls. (Fig.18)
(2) For assembling the control cam, fits a zone (groove) of con-
trol cam to a position of pinch lever and b zone (groove) to
b position of head base shaft. (Fig.18 and 19)
3.2.10 Removing the actuator gear A and B (small)
(Fig.18)
(1) Release the actuator gear A (small) from one pawl and re-
move it toward upward.
(2) Release the actuator gear B (small) from one pawl and re-
move it toward upward.
3.2.11 Removing the actuator gear (large)
(Fig.18)
(1) After removing the control cam, actuator gear A (small) and
actuator gear B (small), remove the actuator gear (large).
Actuator gear A
(small)
Pawl
Pawl
Actuator gear
(large)
Control cam
(chassis side)
b
zone
a
zone
Pinch lever Control cam
Actuator gear B
(small)
Head base shaft
Pawl
Fig.18
a
b
Pinch lever
Fig.19
1-12 (No.MB061)
SECTION 4
ADJUSTMENT
4.1 Measuring instruments required for adjustment
(1) Low - frequency oscillator (oscillation frequency 50 Hz - 20
kHz, 0 dB output with 600 Ω impedance)
(2) Attenuator (600 Ω impedance)
(3) Electronic voltmeter and oscilloscope
(4) Standard tapes
VT712 (tape speed, wow and flutter measurement)
VT727 (400 Hz reference level)
VT742 (63 Hz, 1 kHz, 12.5 kHz) (play back frequency)
VT705 (12.5 kHz) (azimuth)
(5) Recording reference tapes
AC-225 (Normal), AC-514 (TDK SA) (CrO2)
AC-713 (TDK MA) (Metal)
(6) 600 Ω resistors (for attenuator matching)
(7) Distortion meter (band pass filter)
(8) Torque gauge (cassette) for CTG-N, TW2111, TW2121,
TW2231 and TW2241, mechanism adjustments
(9) Wow & flutter meter
(10) Frequency counter meter
(11) M300 gauge
(12) Band pass filter
4.3 Location of adjustment
4.2 Measurement conditions
(1) Power supply voltage (your local voltage)
AC230 V 50 Hz : B/E/EN version
AC120 V 60 Hz : J/C version
AC230/127/110 V 50/60 Hz : UT/U version
(2) Standard position of the switch and volume knob Switches
and volume knobs setting position
INPUT LEVEL : MAXIMUM
DOLBY NR : OFF
REVERSE MODE :
(3) Standard level (0 dBs) is 0.775 V unless otherwise speci-
fied.
(4) The reference value of recording input level is LINE IN level
of a signal whose LINE OUT level is -8 dBs and H.PHONE
OUT level is -24 dBs.
Connection of CN845
CN845
1
5
470k
(L)
(R)
+
F. COUNTER
(BIAS
GND
FREQUENCY
adj.)
+
DC VOLTMETER
V
(HX PRO adj.)
-
+
V
-
DECK B
REC LEVEL
adj.
DECK A
PB FREQ.
RESPONSE adj.
DECK A
PB LEVEL
adj.
VR211 VR111
LR
VR212 VR112
LR
BIAS
FREQUENCY
VR216
L
VR226
R
VR246 VR146
L2401
L8401
B7101
H.SPEED
TP
R L
L1401
L
R
15
CN845
DECK A
DECK A
VR216 VR116
RRL
VR217 VR117
L
NORMAL SPEED adj.
VR703
VR701
VR704
VR702
HIGH SPEED adj.
DECK B
DECK B
DECK B
REC FREQ.
RESPONSE
adj.
HX PRO adj
DECK B
FREQ.
RESPONSE
adj.
DECK B
PB LEVEL
adj.
(No.MB061)1-13
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