Sony CX-LFA660 / CX-LFA770 / XR-FA660 / XR-FA770 Service Manual ▷ View online
17
CX-LFA660/LFA770
SECTION 6
ELECTRICAL ADJUSTMENTS
[Record/Playback Head Azimuth Adjustment]
Procedure:
1. Mode : Playback
2. Turn the adjustment screw and check output peaks. If the peaks
do not match for L-CH and R-CH, turn the adjustment screw
so that outputs match within 1 dB of peak.
so that outputs match within 1 dB of peak.
test tape
P-4-A100
(10kHz, –10dB)
P-4-A100
(10kHz, –10dB)
MAIN board
J201
speaker terminal
J201
speaker terminal
level meter
set
+
–
L-CH
peak
peak
R-CH
peak
peak
screw
position
position
output
level
level
within
1 dB
1 dB
L-CH
peak
peak
R-CH
peak
peak
screw
position
position
within 1dB
DECK SECTION 0 dB=0.775V
1. Demagnetize the record/playback head with a head
demagnetizer.
2. Do not use a magnetized screwdriver for the adjustments.
3. After the adjustments, apply suitable locking compound to
3. After the adjustments, apply suitable locking compound to
the parts adjusted.
4. The adjustments should be performed with the rated power
supply voltage unless otherwise noted.
5. The adjustments should be performed in the order given in
this service manual. (As a general rule, playback circuit
adjustment should be completed before performing recording
circuit adjustment.)
adjustment should be completed before performing recording
circuit adjustment.)
6. The adjustments should be performed for both L-CH and R-
CH.
7. Switches and controls should be set as follows unless otherwise
specified.
4. After the adjustments, apply suitable locking compound to
the parts adjusted.
Adjustment Location: Record/Playback/Erase Head
[Tape Speed Check]
Procedure:
1. Turn the power on.
2. Insert the WS-48B into deck.
3. Press the TAPE nN button of deck.
4. Check the reading of frequency counter becomes 3000
2. Insert the WS-48B into deck.
3. Press the TAPE nN button of deck.
4. Check the reading of frequency counter becomes 3000
±
90
Hz.
Sample Value of Wow and flutter
W.RMS (JIS) less than 0.3%
(test tape: WS-48B)
(test tape: WS-48B)
3. Mode: Playback
test tape
P-4-A100
(10kHz, –10dB)
P-4-A100
(10kHz, –10dB)
oscilloscope
set
Waveform of oscilloscope
in phase
45
°
90
°
135
°
180
°
good
wrong
MAIN board
J201
speaker terminal
J201
speaker terminal
L
R
Signal
Used for
Tape
P-4-A100
WS-48B
10 kHz, –10 dB
3 kHz, 0 dB
Azimuth Adjustment
Tape Speed Adjustment
adjustment screw
18
CX-LFA660/LFA770
RFDC signal waveform
Checking Location: BD81A board (Side B)
CD SECTION
Note:
1. Use YEDS-18 disc (3-702-101-01) unless otherwise indicated.
2. Use an oscilloscope with more than 10M
2. Use an oscilloscope with more than 10M
Ω
impedance.
3. Clean the object lens by an applicator with neutral detergent when the
signal level is low than specified value with the following checks.
RFDC Le
Note:
Note:
Note:
vel Check
Connection:
Procedure:
1.
1.
Connect an oscilloscope to test point (RFDCO) and TP (VC)
on the BD81A board.
on the BD81A board.
2.
Turn the power on.
3.
Put the disc (YEDS-18) in to playback the number five track.
4.
Confirm that oscilloscope waveform is clear and check RFDC
signal level is correct or not.
signal level is correct or not.
A clear RFDC signal waveform means that the shape “
◊
” can be
clearly distinguished at the center of the waveform.
+
–
–
BD81A board
TP (RFDCO)
TP (VC)
oscilloscope
VOLT/DIV: 200 mV
TIME/DIV: 500 ns
TIME/DIV: 500 ns
level: 0.6
±
0.15 Vp-p
RFAC Level Check
Connection:
Procedure:
1.
1.
Connect an oscilloscope to test point TP (RFACO) and TP
(VC) on the BD81A board.
(VC) on the BD81A board.
2.
Turn the power on.
3.
Put the disc (YEDS-18) in to playback the number five track.
4.
Confirm that oscilloscope waveform is clear and check RFAC
signal level is correct or not.
signal level is correct or not.
A clear RFAC signal waveform means that the shape “
◊
” can be
clearly distinguished at the center of the waveform.
RFAC signal waveform
Checking Location: BD81A board (Side B)
+
–
–
BD81A board
TP (RFACO)
TP (VC)
oscilloscope
VOLT/DIV: 200 mV
TIME/DIV: 500 ns
TIME/DIV: 500 ns
level: 1.0
±
0.4 Vp-p
S-curve Check
Connection:
Procedure:
1.
1.
Connect an oscilloscope to test point TP (FEO) and TP (VC)
on the BD81A board.
on the BD81A board.
2.
Turn the power on.
3.
Put the disc (YEDS-18) in and press the button
and actuate the focus search. (actuate the focus search when
disc table is moving in and out)
and actuate the focus search. (actuate the focus search when
disc table is moving in and out)
4.
Check the oscilloscope waveform (S-curve) is symmetrical
between A and B. And confirm peak to peak level within 2
between A and B. And confirm peak to peak level within 2
±
1
Vp-p.
S-curve waveform
• Try to measure several times to make sure than the ratio of A : B
or B : A is more than 10 : 7.
• Take sweep time as long as possible and light up the
brightness to obtain best waveform.
Checking Location: BD81A board (Side B)
+
–
–
BD81A board
TP (FEO)
TP (VC)
oscilloscope
A
B
symmetry
within 2
±
1 Vp-p
CD
NX
19
CX-LFA660/LFA770
Checking Location: BD81A board (Side B)
+
–
–
BD81A board
TP (TEO)
TP (VC)
oscilloscope
Traverse Waveform
0V
B
level: 1.0
±
0.5 Vp-p
Center of
the waveform
the waveform
A (DC
voltage)
Traverse Waveform
0V
Tracking servo
Sled servo
ON
C (DC
voltage)
voltage)
Tracking servo
Sled servo
OFF
6.
Press the button. (The tracking servo and
sledding servo are turned ON)
sledding servo are turned ON)
7. To exit from this mode, turn the power off.
Notes:
• Always move the optical pick-up to most inside track when
exiting from this mode. Otherwise, a disc will not be unloaded.
• Do not run the sled motor excessively, otherwise the gear can
be chipped.
E-F Balance Adjustment
Connection:
Procedure:
1.
1.
Connect an oscilloscpe to test point TP (TEO) and TP (VC) on
the BD81A board.
the BD81A board.
2.
Press three buttons
x
3.
Put the disc (YEDS-18) in to playback the number five track.
4.
Press the button. If it plays, press the
CD
NX
5.
Check the level B of the oscilliscope's waveform and the A
(DC voltage) of the center of the Traverse waveform.
Confirm the following :
A/B x 100 = less than
(DC voltage) of the center of the Traverse waveform.
Confirm the following :
A/B x 100 = less than
±
10%
CD
NX
CD
NX
PLAY MODE/TUNING MODE
and
simulfaneously enter the CD test mode.
Z
CD
Checking Location:
– BD81A BOARD (Side B) –
button again. (The tracking servo and the sledding servo are
turned OFF)
turned OFF)
,
,
(SideB)
BD81A BOARD
IC251
IC301
IC101
IC303
TP
(RFACO)
TP
(VC)
TP
(FEO)
TP
(RFDCO)
TP
(TEO)
21
21
CX-LFA660/LFA770
CX-LFA660/LFA770
SECTION 7
DIAGRAMS
• Circuit Boards Location
PT BOARD
MAIN BOARD
HP BOARD
BD81A BOARD
AMP BOARD
MS-128 BOARD
FRONT BOARD
For Schematic Diagrams.
Note:
• All capacitors are in
Note:
• All capacitors are in
µ
F unless otherwise noted. (p: pF)
50 WV or less are not indicated except for electrolytics and
tantalums.
tantalums.
• All resistors are in
Ω
and
1
/
4
W or less unless otherwise
specified.
•
f
: internal component.
•
C
: panel designation.
•
A
: B+ Line.
•
B
: B– Line.
• Voltages and waveforms are dc with respect to ground
under no-signal (detuned) conditions.
No mark: FM
( )
No mark: FM
( )
: CD STOP
• Voltages are taken with a VOM (Input impedance 10 M
Ω
).
Voltage variations may be noted due to normal production
tolerances.
tolerances.
• Waveforms are taken with a oscilloscope.
Voltage variations may be noted due to normal production
tolerances.
tolerances.
• Circled numbers refer to waveforms.
• Signal path.
F
: TUNER
J
: CD
d
: AUX
E
: PB (TAPE)
a
: REC (TAPE)
For Printed Wiring Boards.
Note:
•
Note:
•
X
: parts extracted from the component side.
•
Y
: parts extracted from the conductor side.
•
f
: internal component.
•
: Pattern from the side which enables seeing.
• Indication of transistor.
• Abbreviation
AUS
: Australian model
THIS NOTE IS COMMON FOR PRINTED WIRING BOARDS AND SCHEMATIC DIAGRAMS.
(In addition to this, the necessary note is printed in each block.)
(In addition to this, the necessary note is printed in each block.)
C
B
These are omitted.
E
Q
B
These are omitted.
C
E
Note: The components identified by mark
0
or dotted
line with mark
0
are critical for safety.
Replace only with part number specified.
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