Sony CFD-S28 Service Manual ▷ View online
– 13 –
SECTION 4
MECHANICAL ADJUSTMENTS
Mode
Tension Meter
Meter Reading
FWD
CQ-403A
more than 100 g
(more than 3.53 oz)
• Tape Tension Measurement
PRECAUTION
1. Clean the following parts with a denatured-alcohol-moistened
swab :
record/playback head
pinch roller
erase head
rubber belts
capstan
idlers
2. Demagnetize the record/playback head with a head demagne-
tizer. (Do not bring the head magnetizer close to the erase head.)
3. Do not use a magnetized screwdriver for the adjustments.
4. After the adjustments, apply suitable locking compound to the
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.
• Torque Measurement
Mode
Torque Meter
Meter Reading
FWD
CQ-102C
30 – 70 g•cm
(0.42 – 0.97 oz•inch)
FWD
CQ-102C
1.5 – 5.5 g•cm
Back Tension
(0.021 – 0.076 oz•inch)
FF
CQ-201B
more than 60 g•cm
(more than 0.83 oz•inch)
REW
CQ-201B
more than 60 g•cm
(more than 0.83 oz•inch)
SECTION 5
ELECTRICAL ADJUSTMENTS
Tape Speed Adjustment
Setting:
Function: TAPE
Function: TAPE
Procedure:
1. Playback WS-48A (tape center) in the FWD state.
2. Adjsut the volume in CAPSTAN/REEL motor (M301) so that
1. Playback WS-48A (tape center) in the FWD state.
2. Adjsut the volume in CAPSTAN/REEL motor (M301) so that
the frequency counter reading becomes 3,000 Hz.
Specification Values: 2,985 to 3,015 Hz
3. Adjust the volume in CAPSTAN/REEL motor (M301) so that
the frequency at the beginning and that at the end of tape wind-
ing are between 2,955 to 3,045 Hz.
ing are between 2,955 to 3,045 Hz.
Adjustment Location:
PRECAUTION
1. Setting
SOUND control : OFF
TAPE DECK SECTION
0 dB=0.775 V
Test tape
Type
Signal
Used for
WS-48A
3 kHz, 0 dB
Tape Speed Adjustment
+
–
–
set
Test tape
WS-48A
(3 kHz, 0 dB)
WS-48A
(3 kHz, 0 dB)
frequency counter
32
Ω
2
jack (J301)
– TAPE deck block –
CAPSTAN /REEL motor
(M301)
(M301)
Tape Speed
Adjustment
Adjustment
– 14 –
TUNER SECTION
0 dB=1
µ
V
[AM]
Setting:
Function : RADIO
BAND button : AM
Function : RADIO
BAND button : AM
[FM]
Setting:
Function : RADIO
BAND button: FM
Function : RADIO
BAND button: FM
• Repeat the procedures in each adjustment several times, and the
tracking adjustments should be finally done by the trimmer ca-
pacitors.
pacitors.
• Remove FM antenna in FM adjustment.
AM IF ADJUSTMENT
Adjust for a maximum reading on level meter
T1
450 kHz
AM VCO VOLTAGE ADJUSTMENT
Adjustment Part
Frequency Display
Reading on Digital Voltmeter
L4
1,710 kHz
4.8
Confirmation
530 kHz
1.0
AM TRACKING ADJUSTMENT
Adjust for a maximum reading on level meter
L3
620 kHz
CT3
1,400 kHz
FM VCO VOLTAGE ADJUSTMENT
Adjustment Part
Frequency Display
Reading on Digital Voltmeter
L2
108 MHz
4.0 ± 0.1 V
Confirmation
87.5 MHz
1.6 ± 0.4 V
FM TRACKING ADJUSTMENT
Adjust for a maximum reading on level meter
L1
87.5 MHz
CT1
108 MHz
Adjustment Location: TUNER board (See page 15)
AM RF signal
generator
30% amplitude
modulation by
400 Hz signal
Output level: as low as possible
modulation by
400 Hz signal
Output level: as low as possible
Put the lead-wire
antenna close to
the set.
antenna close to
the set.
+
–
–
level meter
set
32
Ω
2
jack (J301)
FM RF signal
generator
22.5 kHz frequency
deviation by 400 Hz
signal
Output level: as low as possible
deviation by 400 Hz
signal
Output level: as low as possible
+
–
–
level meter
2
jack (J301)
set
32
Ω
0.01
µ
F
antenna terminal
digital voltmeter
TUNER board
JW17
100 k
Ω
+ 0.7 V
– 0.5 V
– 0.5 V
+ 1.2 V
– 0.6 V
– 0.6 V
– 15 –
Adjustment Location:
AM Tracking
Adjustment
Adjustment
CT3
L3
L3
– TUNER BOARD –
(Component Side)
FM Tracking
Adjustment
Adjustment
L2
FM VCO Voltage
Adjustment
L4
AM VCO Voltage
Adjustment
CT1
L1
L1
Antenna
Terminal
Terminal
JW17
T1
AM IF Adjustment
– 16 –
CD SECTION
CD section adjustments are done automatically in this set.
In case of operation check, confirm that focus bias.
In case of operation check, confirm that focus bias.
Focus Bias Check
1. Connect the oscilloscope to TP (RF) and GND on the MAIN
board.
2. Insert the disc (YEDS-18). (Part No. : 3-702-101-01)
3. Press the
3. Press the
[CD ]
button.
4. Confirm that the oscilloscope waveform is as shown in the
figure below. (eye pattern)
A good eye pattern means that the diamond shape (≈) in the
center of the waveform can be clearly distinguished.
A good eye pattern means that the diamond shape (≈) in the
center of the waveform can be clearly distinguished.
• RF signal reference waveform (eye pattern)
VOLT/DIV: 0.2 V (with the 10: 1 probe in use.)
TIME/DIV: 500 ns
TIME/DIV: 500 ns
1.2
±
0.1 Vp-p
When observing the eye pattern, set the oscilloscope
for AC range and raise vertical sensitivity.
for AC range and raise vertical sensitivity.
Adjustment Location:
– MAIN BOARD (Conductor Side) –
TP (RF)
IC701
fl
Click on the first or last page to see other CFD-S28 service manuals if exist.