Sony WM-DD User manual

SPECIFICATIONS
Power Requirements: 3 V dc
Internal batteries: IEC designation R6
(size A A) x 2
AC power adaptor: Refer to the following
chart to choose the correct adaptor for
your area.
Country
Ac power line
voltage
Optional ac
power adaptor
US
Canadian
120 Vac, 60 Hz
AC-39 available in the
U.S.A. and Canada
UK
240 Vac, 50 Hz
AC-37 available in the
United Kingdom
AEP
220 V ac, 50 Hz
AC-37 available in
European countries
E
120 Vac, (110,220 or
240 V ac, adjustable
by Sony personnel),
50/60 Hz
110,120, 220 or 240 V
ac, adjustable,
50/60 Hz
AC-38 available
in Japan
AC-38 available in
other countries
12 V car battery: Sony DCC-127A* car
battery cord
*For connection with the DCC-127A, the optional PC-
200 dc plug adaptor is required.
Battery Life
(continuous playback
hours): Approx. 9 hours with supplied Sony
Eveready AM3 alkaline batteries
For maximum performance we recommend the use of alkaline bat¬
teries.
Dimensions: Approx. 79 x 109.2 x 29 mm (w/h/d)
(3i/s x4s/ 16 x 13/ie inches)
not incl. projecting parts and controls
Weight: Approx. 290g (IO 1 /4 oz) incl. batteries, not
inch other accessories
MICROFILM
Tape Track:
Fast Winding Time:
Frequency Response:
Wow and Flutter:
Power output:
Output:
4-track 2-channel stereo
Approx. 2min. with Sony Cassette C-60
40 — 15,000 Hz (with the TAPE selector
+ tn METAL*
set t0 CrOj 1
40 — 12,000 Hz (with the TAPE selector
set to NORM)
±0.13% (DIN)
0.08% WRMS (NAB)
25 mWx 2 (max.)
20 mW x 2 (at 10% harmonic distortion)
at dc operation
Headphone jacks (stereo minijack) ... 2
load impedance 8 — 300 ohms
Tape Transport
Mechanism Type
MT-WMDD-24
SERVICE MANUAL

WM-DD
PARTS IDENTIFICATION
O VOLUME control
0 HEADPHONES jacks (stereo minijacks)
© ► ► REW (rewind) button
0^4 FF (fast forward) button
0<4 PLAY (playback) button
0 Lock button (to secure the cassette panel)
0 DC IN 3 V (external power input) jack
© BATTERY indicator
© ■ STOP button
0 TAPE selector
0 Battery compartment (inside)
© Cassette panel
FEATURE
• Capable of selecting NORM or position
by type of tape in use.
• DD (Disc Drive) system that has superior anti-roll¬
ing effect and low wow and flutter has been em¬
ployed.
• Auto shut- off mechanism in FWD mode and auto
off mechanism in FF, REW modes.
i ■
t
2

Chip components
Chip components include resistors, capacitors, transistors,
diodes, coil and adjustable resistors.
In this section, the types of resistors, ceramic capacitors,
transistors and diodes which are used most frequently will
be described.
Dimension of transistors and capacitors
Type
L
W T
3216 3.2
1.6
0.45 ~ 0.6
2125
2.0
1.25
0.35-0.5
Identification
electrode ceramic base side
(white color)
electrodes
Resistor
Laminated Ceramic Capacitor
Transistor
Diode

Replacing chip components
All chip components should be connected and disconnect¬
ed, using a tapered soldering iron [temperature of the iron
tip: less than 280°C (536°F)], a pair of tweezers and braid¬
ed wire.
Precautions for replacement
1. Do not disconnect the chip component forcefully.
Otherwise, the pattern may peel off.
2. Never re-use a disconnected chip component. Dispose of
all old chip components.
3. To protect the chip component, heating time for attach¬
ing the component should be within 3 seconds.
o Removing chip components
(1) R emoving solder at electrode
Remove the solder at the electrode, using a thin
braided wire. Do not remove the solder of the part
(chip component) attached adjacent to the electrode.
(2) D i sconnecting chip components
Turn the tweezers with the soldering iron alternately
applied to both electrodes, and the chip component
will be disconnected. Take careful precautions while
disconnecting, because if the chip component is force¬
fully removed the land may peel off.
Never re-use a disconnected chip component.
/ Turn
(3) S moothing the soldered surface
After disconnecting the chip component, remove the
solder by using a braided wire to smooth the land
surface.
o Connecting chip components
The value of chip components is not displayed on the
main body. Take due precautions to avoid mixing new
chip components with other ones.
(1) A pplying solder to land on one side
Apply a thin layer of solder to the land on one side
where the chip component is to be connected. Too
much solder may cause bridging.
Small quantity of solder
(2) S peedy soldering
Hold the chip component at the desired position,
using tweezers, and apply the soldering iron in the
arrow-marked direction. To protect the chip compo¬
nent, heating time should be within 3 seconds.
Land prin ted circui t board
(3) S p eedy soldering of electrode on the other side
Solder the electrode on the other side in the same
way as in (2) above.

WM-DD
2-1. FWD mode
SECTION 2
MECHANICAL OPERATION
head chassis

WM-DD

WM-DD WM-DD
1. Motor section installation
0 Tighten loosely
@ Tighten firmly
Wow & flutter and motor position
1. Adjust with the thrust screw so that rotor
thrust play is within 0.1 mm. (When confirming
play, press motor down so that the motor
pulley and rotor rubber section do not touch.)
2. Adjust with the adjustment screw so that con¬
sumed current satisfies the value below in FWD
mode.
Consumed current:
Approx. 5 mA higher current than mini¬
mum point, in tightening direction.
Note: If the adjustment screw is loosened too
much, adjustment will be impossible.
Perform adjustment within 5 turns from
the tightened state.
3. Confirm that the wow meter value is 0.08%W*
RMS.
Conditions: — FWD state
— power supply voltage: 2.5 V
-tape: WS-48 (3 kHz, 0 dB)
Use portion near the end.
4. At 2 V power supply voltage, confirm normal
FWD operation.
5. When @ and @ are not satisfied, repeat ad¬
justment again starting with “Motor Section
Installation”.
O Tighten screw loosely.
© Tighten screw while pressing
the motor section lightly in
in the direction of the arrow.
© Tighten the screw.
Press down
adjustment screw
adjustment screw
4-2. ELECTRICAL ADJUSTMENTS
Head Height Adjustment
1. Prepare an adjustment cassette as shown below.
C-120
tape cassette
portions.
2. In playback mode and viewing from the front,
adjust the head heights to eliminate tape curl
and tape twist at portions shown by the arrow.
~8
rCZT
m. —
7
1
tape guide
U
playback head
—n
3r
3-578-138-01 (t= 0.1)
3-578-138-11 ft =0.2)
Shim, head height adjustment
3. If necessary, adjust the height of the tape-guide
by turning the adjustment screw.
adjustment screw
4. Apply locking compound on adjustment screw.
Playback Head Azimuth Adjustment
Procedure:
1. Mode: playback
test tape
P-4-A81
(6.3kHz,-10dB)
HEADPHONES
2. Turn the adjustment screw for the maximum
output levels. If these levels do not match, turn
the adjustment screw until both of output
levels match together within 0.5 dB.
output
levels
within J
0.5 dB^
Screw ^ ■ —
position
3. Phase Check
Mode: playback
test
P-4-A81
(6.3 kHz, -10dB)
L-CH R-CH
peak peak
33 £2 oscilloscope
HEADPHONES
Screen pattern
0@© ®Q
( i n phase 45° 90° f 13 5° 180°,
good wrong
Adjustment Location:
12

SECTION 3
DISASSEMBLY
Note: Follow the disassembly procedure in the numerical order given.
CONTROL PANEL
CASSETTE PANEL
(Compression coil Installation)
Control panel can be removed together with
cassette panel.
screw
O precision screw
P 1.4x3.5, TYPE 1
© precision screw
P 1.4 x 2.5, TYPE 1
screw
© Depress the FF and REWbuttons.
control panel
AUDIO BOARD
HOLDER
© precision screw
P 1.4x3 5 (TYPE 3)
Turn the holder a half turn in the direction
shown by the arrow, and remove the holder
taking care to protruding parts.
(With main board removed)
Be careful not to lose.
© precision screw
P 1.4x2, TYPE 1
Mechanism
section
Main Board
Be careful
not to lose.
protruding part
protruding part
© wire holder
0 wire holder
© Raise up the circuit board
taking care not to break
the lead wires.
A precision screw
P 1.4x2, TYPE 1
holder
Pinch roller and head
can be replaced.
Mechanism section can
be checked.
SECTION 4
ADJUSTMENTS
PRECAUTION
1. Clean the following parts with a denatured-
alcohol-moistened swab:
playback head pinch roller
capstan rubber belts
2. Demagnetize the playback head with a head
demagnetizer.
3. Do not use a magnetized screwdriver for the
adjustments.
4. After the adjustments, apply suitable locking
compound to the parts adjusted.
5. The adjustments should be performed with the
rated power supply voltage unless otherwise
noted.