Sony HCD-H551 User manual

— 1 —
COMPACT DISC DECK RECEIVER
HCD-H551
AEP Model
UK Model
E Model
Tourist Model
SERVICE MANUAL
HCD-H551 is the tuner, deck, CD and
amplifier section in MHC-G55/551.
Model Name Using Similar Mechanism NEW
CD Mechanism Type CDM28-5BD19
Base Unit Type BU-5BD19
Optical Pick-up Type KSS-213BA/F-NP
Model Name Using Similar Mechanism HCD-H501
Tape Transport Mechanism Type TCM-220WR2E
Dolby noise reduction manufactured under license from
Dolby Laboratories Licensing Corporation.
“DOLBY” and the double-D symbol aare trademarks of
Dolby Laboratories Licensing Corporation.
SPECIFICATIONS
Photo: E model
MICROFILM
CD
SECTION
TAPE
DECK
SECTION
CD player section
System Compact disc and digital
audio system
Laser Semiconductor (λ= 780nm)
Emission duration:
continuous
Laser output Max 44.6 µW*
*This output is the value
measured at a distance of
200mm from the objective
lens surface on the Optical
Pick-up Block with 7mm
aperture.
Wavelength 780 – 790 nm
Frequency response
2 Hz – 20 kHz (±0.5 dB)
Signal-to-noise ratio
More than 90 dB
Dynamic range More than 90 dB
Tuner section
FM stereo, FM/AM superheterodyne tuner
FM tuner section
East European model:
65.0 – 78.0 MHz,
87.5 – 108.0 MHz — Continue on next page —
Tourist model: 76.0 – 108.0 MHz
Other models: 87.5 – 108.0 MHz
Aerial FM lead aerial
Aerial terminals 75 ohm unbalanced
Intermediate frequency
10.7 MHz
AM tuner section
Tuning range
German, Italian models:
AM: 531 – 1,602 kHz (with
the interval set at 9 kHz)
AEP, UK, East European models:
MW: 531 – 1,602 kHz (with
the interval set at 9 kHz)
LW: 153 – 279 kHz (with
the interval set at 3 kHz)
Other models:
MW: 531 – 1,602 kHz (with
the interval set at 9 kHz)
530 – 1,710 kHz (with the
interval set at 10 kHz)
SW: 5.95 – 17.90 MHz

— 2 —
Aerial AM loop aerial,
External aerial terminals
Intermediate frequency
450 kHz
Amplifier section
AEP, UK, German, Italian, East European
models:
DIN power output
20 W + 20 W (6 ohms, at
1 kHz, DIN)
Continuous RMS power output
30W+30W (6 ohms, at
1kHz, 10% THD)
Music power output
40 W + 40 W (6 ohms, at
1 kHz, 10% THD)
E, Saudi Arabia, Hong Kong, Singapore,
Malaysia,Taiwan, Tourist,Thailand, Indonesian
models:
Peak music power output
400 W
Continuous RMS power output
30 W + 30 W (6 ohms at
1 kHz, 10% THD)
Inputs
VIDEO IN (phono jacks):
Voltage 250 mV,
impedance 47 kilohms
MIX MIC (phone jacks):
ensitivity 1 mV,
impedance 10 kilohms
Outputs
PHONES (stereo phone jack):
acceptsheadphones of 8ohms
or more.
SPEAKER: accepts impedance of 6 to
16 ohms.
E, Saudi Arabia, Hong Kong,
Singapore, Malaysia, Taiwan, Tourist,
Thailand, Indonesian models:
SUPPER WOOFER:
Voltage 1 V, impedance
1 kilohms
Tape player section
Recording system4-track 2-channel stereo
Frequency response
(DOLBY NR OFF)
40 – 13,000 Hz (±3 dB),
using Sony TYPE I cassette
40 – 14,000 Hz (±3 dB),
using Sony TYPE II cassette
Wow and flutter ±0.15% W.Peak (IEC)
0.1% W.RMS (NAB)
±0.2% W.Peak (DIN)
General
Power requirements
AEP, UK, German, Italian, East European
models: 220 – 230 V AC, 50/60 Hz
Malaysia model:
220 – 240 V AC, 50/60 Hz
Thailand model:
220 V AC, 50/60 Hz
Other models:
110 – 120 V or 220 – 240 V
AC, 50/60 Hz
Adjustable with the voltage
selector
Power consumption
67 W
Dimensions Approx. 280 x 325 x 360 mm
(11 1/8 x 12 7/8 x 14 1/4 in)
(w/h/d)
incl. projecting parts and
controls
Mass Approx. 7.5 kg (16 lb 9 oz)
Design and specifications are subject to
change without notice.

— 3 —
SAFETY-RELATED COMPONENT WARNING !!
COMPONENTS IDENTIFIED BY MARK !OR DOTTED
LINEWITH MARK !ONTHESCHEMATIC DIAGRAMS AND
INTHE PARTS LIST ARE CRITICALTO SAFE OPERATION.
REPLACE THESE COMPONENTS WITH SONY PARTS
WHOSE PART NUMBERS APPEAR AS SHOWN IN THIS
MANUAL OR IN SUPPLEMENTS PUBLISHED BY SONY.
MODEL IDENTIFICATION
— BACK PANEL —
Parts No.
CAUTION
Use of controls or adjustments or performance of procedures
other than those specified herein may result in hazardous
radiation exposure.
Notes on chip component replacement
• Never reuse a disconnected chip component.
• Notice that the minus side of a tantalum capacitor may be
damaged by heat.
Flexible Circuit Board Repairing
• Keep the temperature of soldering iron around 270˚C
during repairing.
• Do not touch the soldering iron on the same conductor of the
circuit board (within 3 times).
• Be careful not to apply force on the conductor when soldering
or unsoldering.
Laser component in this product is capable of emitting radiation
exceeding the limit for Class 1.
This appliance is classified as a
CLASS 1 LASER product.
The CLASS 1 LASER
PRODUCT MARKING is
located on the rear exterior.
AEP model
UK model
German model
Italian model
East European model
E model
Saudi Arabia, Taiwan model
Malaysia model
Singapore model
Hong Kong model
Tourist model
Indonesian model
Thailand model
4-979-273-0π
4-979-273-1π
4-979-273-2π
4-979-273-3π
4-979-273-4π
4-979-274-0π
4-979-274-1π
4-979-274-2π
4-979-274-3π
4-979-274-4π
4-979-274-5π
4-979-274-6π
4-979-274-7π
PARTS No.MODEL
This caution
label is located
inside the unit.

— 4 —
Section Title Page
SECTION 7. EXPLODED VIEWS
7-1. Case Section ...................................................................... 71
7-2. Back Panel Section ............................................................ 72
7-3. Front Panel Section 1......................................................... 73
7-4. Front Panel Section 2......................................................... 74
7-5. CD Mechanism Section (CDM28-5BD19) ....................... 75
7-6. Base Unit Section (BU-5BD19) ........................................ 76
7-7. TC Mechanism Section 1 (TCM-220WR2E).................... 77
7-8. TC Mechanism Section 2 (TCM-220WR2E).................... 78
SECTION 8. ELECTRICAL PARTS LIST .................... 79
Section Title Page
SECTION 1. SERVICING NOTE................................5
SECTION 2. GENERAL ....................................................... 6
SECTION 3. DISASSEMBLY
3-1. Front Panel .......................................................................... 8
3-2. TC Mechanism Deck ........................................................... 8
3-3. HP Board, Jog Board and Panel Board ............................... 9
3-4. CD Block ........................................................................... 10
3-5. CD Mechanism Deck ........................................................ 10
SECTION 4. MECHANICAL ADJUSTMENTS .......... 11
SECTION 5. ELECTRICAL ADJUSTMENTS
DECK Section ............................................................................. 11
TUNER Section........................................................................... 14
CD Section................................................................................... 16
SECTION 6. DIAGRAMS
6-1. Circuit Boards Location .................................................... 18
6-2. Block Diagrams
• Tuner Section (AEP, UK, G, IT, EE Model) .................. 19
• Tuner Section
(E, EA, SP, MY, TW, HK, IA, JE Model) ...................... 21
• Tuner Section (TH Model) ............................................. 23
• Deck Section .................................................................. 25
• CD Section ..................................................................... 27
• Main Section .................................................................. 29
6-3. Printed Wiring Board — Tuner Section —
(AEP, UK, G, IT, EE Model)............................................. 31
6-4. Schematic Diagram — Tuner Section —
(AEP, UK, G, IT, EE Model)............................................. 32
6-5. Printed Wiring Board — Tuner Section —
(E, EA, SP, MY, TW, HK, IA, JE Model).......................... 34
6-6. Schematic Diagram — Tuner Section —
(E, EA, SP, MY, TW, HK, IA, JE Model).......................... 37
6-7. Printed Wiring Board — Tuner Section —
(TH Model)........................................................................ 37
6-8. Schematic Diagram — Tuner Section —
(TH Model)........................................................................ 38
6-9. Printed Wiring Board — Main Section — ........................ 42
6-10. Schematic Diagram — Main Section — ........................... 45
6-11. Schematic Diagram — Deck Section — ........................... 49
6-12. Printed Wiring Board — Deck Section — ........................ 53
6-13. Printed Wiring Board — Panel Section — ........................ 55
6-14. Schematic Diagram — Panel Section —........................... 57
6-15. Schematic Diagram — CD Section — .............................. 61
6-16. Printed Wiring Board — CD Section — ........................... 63
6-17. IC Block Diagrams — CD Section — .............................. 65
6-18. IC Pin Functions
• IC501 Graphic Control (ASD042) .................................. 67
• IC701 Master Control (TMP87CP64YF) ....................... 68
TABLE OF CONTENTS
• Abbreviation
G: German model.
IT: Italian model.
EE: East European model.
EA: Saudi Arabia model.
SP: Singapore model.
MY: Malaysia model.
TW: Taiwan model.
HK: Hong Kong model.
IA: Indonesian model.
TH: Thailand model.
JE: Tourist model.

— 5 —
NOTES ON LASER DIODE EMISSION CHECK
The laser beam on this model is concentrated so as to be focused on
the disc reflective surface by the objective lens in the optical pick-up
block. Therefore, when checking the laser diode emission, observe
from more than 30 cm away from the objective lens.
[Switching the channel step 9 KHz/10 KHz]
Press ENTER/NEXT button and POWER button simultaneously
to switch the AM channel step 9 KHz and 10 KHz. Be sure not to
change with carelessness.
When the AMS dial is rotated in the clockwise direction, the count
increases in the following order.
J1 nJ2 nJ3.
When rotated in the counterclockwise direction, it decreases in the
following order.
J0 nJ9 nJ8.
To exit form the test mode, press the TUNER/BAND , DISPLAY/
DEMO , MENU 2 buttons simultaneously again.
SECTION 1
SERVICING NOTE
NOTES ON HANDLINGTHE OPTICAL PICK-UP BLOCK
OR BASE UNIT
The laser diode in the optical pick-up block may suffer electrostatic
break-down because of the potential difference generated by the
charged electrostatic load, etc. on clothing and the human body.
During repair, pay attention to electrostatic break-down and also use
the procedure in the printed matter which is included in the repair
parts.
The flexible board is easily damaged and should be handled with
care.
HOW TO OPEN THE DISC TRAY WHEN POWER SWITCH
TURNS OFF
[FL DisplayTube, LED All Lit and Key Check mode]
When the TUNER/BAND , DISPLAY/DEMO , and MENU 2
buttons are pressed simultaneously, the FL display tube and LEDs
will all light up. Press any button to enter the key check mode.
When the key check mode is entered, the FL display tube displays
“K 1 J0 V0”. Each time a button is pressed, the counter increases in
the following order, K 2 nK 3 nK 4.
If buttons already pressed once are pressed again, the counter will
not increase. When the VOLUME knob is rotated in the + direction,
the count increases in the following order.
V1 nV2 nV3.
When rotated in the–direction, it decreases in the following order.
V0 nV9 nV8.
Insert a tapering driver into the aperture of the unit bottom, and
turn in the direction of arrow.
* To close the disc tray, turn the driver in the reverse direction.

— 6 —
SECTION 2
GENERAL This section is extracted from
instruction manual.
(AEP, UK, German, Italian, East European
models)
(E, Saudi Arabia, Hong Kong, Malaysia,
Singapore, Taiwan, Tourist, Thailand,
Indonesian models)
1VIDEO IN jacks (22)
2SPEAKER L/R connectors (4)
3SUPER WOOFER jack (22)
4ANTENNA terminals (4)
5Voltage selector (Except Malaysia, Thailand
models) (5)

— 7 —

— 8 —
SECTION 3
DISASSEMBLY
Note: Follow the disassembly procedure in the numerical order given.
3-1. FRONT PANEL
3-2.TC MECHANISM DECK
1 Remove the connectors
(Main board: CN402, CN702)
(HP board: CN513)
6 TC mechanism deck
5 Three screws
(+BVTP2.6X8)
3 Cassette holder
assembly (A), (B)
4 Torsion spring
(L), (R)
1 Push the EJECT button.
(Two positions)
2 Remove the claws
(Four positions)
4 Two screws
(+BVTP2.6X8)
CN402
CN702
2 Two screws
(+BVTT3X8)
CN513
5 Remove the claws
(Three positions)
3 Two screws
(+BVTT3X8)

— 9 —
.
3-3. HP BOARD, JOG BOARD AND PANEL BOARD
* Note: It will be easy to remove if you push
lightly from the hole of the JOG board
with some screwdrivers or etc.
3 Nut
1 Knob (VOL) * Note
2 Knob (JOG) * Note
4 Nut
0 Three claws
!¡ Claw
9 Two claws
!£ Panel board
8 Six screws
(+BVTP2.6X8)
6 HP board
5 Two screws
(+BVTP2.6X8)
!™ JOG board
7 Six screws
(+BVTP2.6X8)
Screw driver

— 10 —
3-5. CD MECHANISM DECK
3-4. CD BLOCK
1 Remove the connectors
(Main board: CN201)
(Loading board: CN291)
4 CD block
(CD mechanism deck
and CD chassis)
3 Two screws
(+BVTP3X8)
2 PC board holder
CN291
CN201
3 Remove the CD mechanism
deck direction of arrow.
1 Two screws
(+BVTP3X8)
2 Two claws

— 11 —
Precaution
1. Clean the following parts with a denatured alcohol-moistened
swab:
record/playback heads pinch rollers
erase head rubber belts
capstan idlers
2. Demagnetize the record/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.
Torque Measurement
SECTION 4
MECHANICAL ADJUSTMENTS SECTION 5
ELECTRICAL ADJUSTMENTS
DECK SECTION 0 dB=0.775V
1. Demagnetize the record/playback head with a head damagnetizer.
2. Do not use a magnetized screwdriver for the adjustments.
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.)
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.
DOLBY NR switch: OFF
FWD
REV
REV
back tension
FF/REW
FWD tension
CQ-102C
CQ-102C
CQ-102RC
CQ-102RC
CQ-201B
CQ-403A
CQ-403R
2 to 6 g • cm
(0.02 - 0.08 oz • inch)
36 to 61 g • cm
(0.5 - 0.84 oz • inch)
2 to 6 g • cm
(0.02 - 0.08 oz • inch)
61 to 143 g • cm
(0.85 - 1.99 oz • inch)
100 g or more
(3.53 oz or more)
100 g or more
(3.53 oz or more)
FWD
back tension
REV tension
Torque Torque meter Meter reading
36 to 61 g • cm
(0.5 - 0.84 oz • inch) SignalTape Used for
P-4-A100
WS-48B
P-4-L300
10 kHz, –10 dB
3 kHz, 0 dB
315 Hz, 0 dB
Azimuth Adjustment
Tape Speed Adjustment
Level Adjustment
Record/Playback Head Azimuth Adjustment
(Deck A, Deck B)
Note: Perform this adjustments for both decks.
Procedure:
1. Mode : Playback
test tape
P-4-A100
(10kHz, –10dB) main board
CN403
Pin 3 (L-CH)
Pin 1 (R-CH)
set
main board
CN403
Pin 2 (GND)
level meter
+
–

— 12 —
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.
3. Mode: Playback
main board
CN403
Pin 3 (L-CH)
Pin 2 (GND)
set L
R
test tape
P-4-A100
(10kHz, –10dB)
oscilloscope
Waveform of oscilloscope
in phase 45˚ 90˚ 135˚ 180˚
wrong
good
Pin 1 (R-CH)
Tape Speed Adjustment (Deck A)
Note: Start the Tape Speed adjustment as below after setting the
test mode.
The tape speed can be changed with the HIGH SPEED
DUBBING button during the test mode.
Method :
1. Turn the power switch on.
2. Press the DISPLAY/DEMO button, MENU 1 button and
TUNER/BAND button simultaneously.
Procedure :
Mode: Playback
frequency counter
+
–
main board
CN403 Pin 3 (L-CH)
Pin 1 (R-CH)
set
test tape WS-48B
(3kHz, 0dB)
1. Insert the WS-48B into the deck A to playback.
2. Press the HIGH SPEED DUBBING button. Then at HIGH
SPEED mode.
3. Adjust the RV652 on the MD board so that the frequency
counter reading becomes 6,000 ± 30 Hz.
4. Press the HIGH SPEED DUBBING button again to be set the
NORMAL SPEED mode.
5. Set to the playback mode.
6. Adjust the RV651 on the MD board so that the frequency
counter reading becomes 3,000 ± 15 Hz.
Frequency difference between deck A and deck B the beginning
of the tape should be within ± 1.5%.
Adjustment Location: MD board
Playback Level Adjustment (Deck A, Deck B)
Procedure:
Mode: Playback
set
main board
CN403 Pin 3 (L-CH)
Pin 1 (R-CH)
level meter
Deck A is RV311 (L-CH) and RV411 (R-CH), deck B is RV301
(L-CH) and RV401 (R-CH)
so that adjustment within the following adjustment level.
Adjustment level:
CN403 playback level: 301.5 to 338.3 mV (–8.2 to –7.2 dB)
level difference between the channels: within ± 0.5 dB
Adjustment Location: MD board
test tape P-4-L300
(315Hz, 0dB)
L-CH
peak output
level within
1dB within 1dB
R-CH
peak
screw
position L-CH
peak
screw
position
R-CH
peak
4. After the adjustments, apply suitable locking compound to the
parts adjusted.
Adjustment Location: Playback Head (Deck A)
Record/Playback/Erase Head (Deck B)
Adjustment screw
FWD side REV side

— 13 —
Record Level Adjustment (Deck B)
Procedure:
1. Press FUNCTION button to Select VIDEO.
2. Mode: record
blank tape
CS-123
Record Bias Adjustment (Deck B)
Procedure:
1. Press FUNCTION button to Select VIDEO.
2. Mode: record
4. Confirm playback the signal recorded in step 2 become adjustment
level as follows.
If these levels do not adjustment level, adjust the RV341 (L-CH)
and RV441 (R-CH) on the MD board to repeat steps 2 and 3.
Adjustment level: The playback output of 10 kHz level difference
against 315 Hz reference should be ± 0.5 dB.
Adjustment Location: MD board
VIDEO IN
1) 315Hz
2) 10kHz
} 50 mV (–23.8 dB)
AF OSC
attenuator 600 blank tape
CS-123
set
main board
CN403 Pin 3 (L-CH)
Pin 1 (R-CH)
level meter
recorded
position
set
3. Mode: Playback
Adjustment Location:
[MD BOARD] (Conductor Side)
VIDEO IN
315kHz 50mV (–23.8 dB)
AF OSC
attenuator 600
set
3. Mode: Playback
recorded
portion
set
main board
CN403 Pin 3 (L-CH)
Pin 1 (R-CH)
4. Confirm playback the signal recorded in step 2 become adjustment
level as follows.
If these levels do not adjustment level, adjust the RV301 (L-CH)
and RV351 (R-CH) on the main board to repeat steps 2 and 3.
Adjustment level:
CN403 PB level: 47.3 to 53.1 mV (–24.3 to –23.3 dB)
Adjustment Location: MAIN board
RV301
IC401
13
CN403 RV351
RV351
Record Level Adjustment
(R CH)
RV301
RecordLevelAdjustment
(L CH)
RV341 (L CH), 441 (R CH)
Record Bias Adjustment
RV301
RV401 RV341 RV651 RV652
RV311
RV411
RV301 (L CH), 401(R CH)
Playback Level Adjustment
(Deck B)
RV441
RV311 (L CH), 411 (R CH)
Playback Level Adjustment
(Deck A)
level meter
RV651 (Normal speed)
RV652 (High speed)
Tape Speed Adjustment
[MAIN BOARD] (Component Side)

— 14 —
TUNER SECTION 0dB=1µV
Note: As a front-end (FE1) is difficult to repair if faulty, replace it
with new one.
AMTuned Level Adjustment
Note: FM Tuned Level adjustment should be performed after this
AM Tuned Level Adjustment.
Setting:
Band: AM or MW
loop antenna
(Supplied accessories)
AM RF SSG
loop antenna
30% amplitude
modulation by
400Hz signal
60cm AM antenna
terminal (TM1)
Field strength dB (µV/m) = SSG output level dB (µV/m) –26dB.
Modulation: 999 kHz (at 9 kHz step)
1,050 kHz (at 10 kHz step)
Procedure:
1. Supply a 25 dB 98 MHz signal from the ANTENNA terminal.
2. Tune the set to 98 MHz.
3. Adjust RV42 (EXCEPT Thailand model), RV41 (Thailand model)
to the point (moment) when the TUNED indicator will change
from going off to going on.
Adjustment Location: TCB board
set
Procedure:
1. Set the output of SSG so that the input level of the set becomes 55
dB.
2. Tune the set to 999 kHz or 1,050 kHz.
3. Adjust RV41 (EXCEPT Thailand model), RV42 (Thailand model)
to the point (moment) when the TUNED indicator will change
from going off to going on.
Adjustment Location: TCB board
FMTuned Level Adjustment
Note:This adjustment should be afterAM Tuned LevelAdjustment.
Setting:
Band: FM
FM RF stereo signal
generator
75 coaxial
set
Carrier frequency: 98MHz
Modulation: AUDIO 1kHz, 75kHz
deviation (100%)
Output level: 25dB (at 75 open)
Adjustment Location:
EXCEPT Thailand model
[TCB BOARD] (Component Side)
RV41
AM Tuned Level
Adjustment
RV41
TM1
IC41
RV42
RV42
FM Tuned Level
Adjustment
FE1
Thailand model
[TCB BOARD] (Component Side)
RV41
FM Tuned Level
Adjustment
IC2
RV41
RV42
AM Tuned Level
Adjustment
RV42
TM1
FE1
FM ANTENNA terminal
(TM1)

— 15 —
SW OSC Voltage Adjustment
(E, EA, MY, SP, HK, TW, IA model)
Setting:
Band: SW
Procedure:
1. Connect digital Voltmeter to diode D1 center lead and ground.
2. Adjust for a following value reading on digital voltmeter.
Procedure:
Adjust for maximum reading on level meter.
Adjustment Location:
[TCB BOARD] — Component Side —
D1, CV2, T2
SW OSC Voltage
Adjustment
IC41
CV2 CV1
D1
T2 T1 TM1
CV1, T1
SW Tracking
Adjustment
• Abbreviation
EA: Saudi Arabia model.
MY: Malaysia model.
SP: Singapore model.
HK: Hong Kong model.
TW: Taiwan model.
IA: Indonesian model.
Set frequency
5.95 MHz
17.9 MHz
T2
CV2
1.2 ± 0.1 V
8.5 ± 0.2 V
Adjustment
part Reading on digital
voltmeter
SW
SW Tracking Adjustment
(E, EA, MY, SP, HK, TW, IA model)
Setting:
Band: SW
AM RF SSG
set
level meter
SPEAKER terminal
AM ANTENNA terminal
30% amplitude
modulation by
400Hz signal
Set frequency
SW 7 MHz
17 MHz
T1
CV1
• Repeat the procedures is each adjustment several times, and the
frequency coverage and tracking adjustment should be finally done
by the trimmer capacitors.
Adjustment
part

— 16 —
CD SECTION
Note:
1. CD Block is basically designed to operate without adjustment.
Therefore, check each item in order given.
2. UseYEDS-18 disc (3-702-101-01) unless otherwise indicated.
3. Use an oscilloscope with more than 10M impedance.
4. Clean the object lens by an applicator with neutral detergent when
the signal level is low than specified value with the following
checks.
5. Adjust the focus bias adjustment when optical block is replaced.
Focus Bias Adjustment
S Curve Check
Procedure :
BD board
TP (RF)
TP (VC)
oscilloscope
Procedure:
1. Connect oscilloscope to test point TP (RF).
(Ground terminal : TP (VC))
2. Turned Power switch on.
3. Put disc (YEDS-18) in and playback.
4. Adjust RV101 so that the waveform is clear.
(ClearRFsignalwaveformmeansthattheshape“ ” can be clearly
distinguished at the center of the waveform.)
5. After adjustment, check the RF signal level.
• RF signal
VOLT/DIV: 200 mV
TIME/DIV: 500 nS
level: 1.3 ± 0.3 Vp-p
BD board
TP (FE)
TP (VC)
oscilloscope
1. Connect oscilloscope to test point TP (FEO).
2. Connect between test point TP (FOK) and Ground by lead wire.
3. Turn Power switch on.
4. Put disc (YEDS-18) in and turned Power switch on again and
actuate the focus search. (actuate the focus search when disc table
is moving in and out.)
5. Check the oscilloscope waveform (S-curve) is symmetrical
betweenA and B.And confirm peak to peak level within 2.4 ± 0.7
Vp-p.
S-curve waveform
6. After check, remove the lead wire connected in step 2.
VOLT/DIV: 200 mV
TIME/DIV: 500 nS
A
B
symmetry
within 2.4 ± 0.7 Vp-p
Note: • 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.
RF Level Check
Procedure :
BD board
oscilloscope
TP (RF)
TP (VC)
1. Connect oscilloscope to test point TP (RF) on BD board.
2. Turned Power switch on.
3. Put disc (YEDS-18) in and playback.
4. Confirm that oscilloscope waveform is clear and check RF signal
level is correct or not.
Note: Clear RF signal waveform means that the shape “ ” can be
clearly distinguished at the center of the waveform.
RF signal waveform
level: 1.3 ± 0.3 Vp-p

— 17 —
Adjustment Location:
[BD BOARD] — Component Side —
E-F Balance Check
Procedure:
1. Connect test point TP701 (ADJ) on Main board to Ground with a
lead wire.
2. Connect oscilloscpe to test point TP (TEO).
3. Turned Power switch on.
4. Put disc (YEDS-18) in and playback.
5. Confirm that the oscilloscope waveform is symmetrical on the
top and bottom in relation to 0Vdc, and check this level.
Traverse waveform
[MAIN BOARD] — Conductor Side —
IC701
TP701
(ADJ)
oscilloscope
BD board
TP (TEO)
TP (VC)
0V
A
B
level: 300 ± 100 mVp-p
Specified level: • x 100 = less than ± 7%
• A + B = 300 ± 100 mVp-p
6. Remove the lead wire connected in step 1.
Focus/Tracking Gain Adjustment (RV102, RV103)
This gain has a margin, so even if it is slightly off.
There is no problem.
Therfore, do not perform this adjustment.
Please note that it should be fixed to mechanical center position when
you moved and do not know original position.
A – B
2 (A + B)
RF
RV101
IC101
FOK
RV102
TEO FEO
TEI
FEI
VC
RV103
IC104
GND
PCK
IC102

— 18 —
SECTION 6
DIAGRAMS
6-1. CIRCUIT BOARDS LOCATION
BD board
MD board (including p A)
p A
MOTOR board
Note: p A is including in MD board.
TCB board
MAIN board
TRANSFORMER board
PANEL board
HP board
JOG board POWER AMP board
LOADING board
LEAF SWITCH board