LG GCE-8480B User manual

3
INTRODUCTION
FEATURES
1. General
1) Enhanced IDE interface.
2) Internal 5.25 inch, halfheight CD-R/RW Drive.
3) 2Mbytes buffer memory.
4) Audio CD like tray loading of a disc without using a caddy.
5) Power loading and power ejecting of a disc. The disc can also be ejected manually.
6) Supports Power saving mode and Sleep mode.
7) Vertical and Horizontal operation.
8) SuperLink Function.
2. Supported disc formats
1) Reads and writes data in each CD-ROM, CD-ROMXA, CD-I FMV, Video CD, and CD-EXTRA
2) Reads data in Photo CD (Single and Multi session).
3) Reads and writes standard CD-DA.
4) Reads and writes CD-R discs conforming to “Orange Book Part 2”.
5) Reads and writes CD-RW discs conforming to “Orange Book Parts 3”.
3. Supported write method
1) Disc at once (DAO), Session at once (SAO), Track at once (TAO), Variable packet, Fixed packet, and
Multi-session.
4. Performance
1) Random 100 ms average access time.
2) CD-R Record speed : 8X, 12X, 16X, 20X~40X (PCAV), 48X CAV.
3) CD-RW Record speed : 4X, 10X, 12X, 16X.
4) CD-ROM : Max 7,200 KB/s(Max 48x) Sustained Transfer rate.
5) Supports real time error correction and real time layered error correction at each speed.
6) PIO Mode 4, Multi DMA Mode 2, UDMA Mode 2.
7) Multimedia MPC-3 Spec compliant.
8) Support CD-TEXT read/write.
5. Audio
1) Output 16 bit digital data over ATA interface.
2) 8 Times Digital Filter for CD Audio
3) Software Volume Control
4) Equipped with audio line output and headphone jack for audio CD playback.
5) Front panel Volume Control for Headphone Output.
This service manual provides a variety of service
information.
It contains the mechanical structure of the CD-
R/RW Drive and the electronic circuits in
schematic form. This CD-R/RW Drive was
manufactured and assembled under our strict
quality control standards and meets or exceeds
industry specifications and standards.
This CD-R/RW drive is an internal drive unit
designed for use with IBM PC, HP Vectra, or
compatible computer. It can write as much as 700
Mbytes of digital data into CD-R/RW disc, and can
read as much as 650 Mbytes of digital data stored
in a CD-ROM, CD-R and CD-RW disc.
This CD-R/RW Drive can easily meet the
upcoming MPC level 3 specification, and its
Enhanced Intelligent Device Electronics (E-IDE)
and ATAPI interface allows Plug and play
integration in the majority of today’s PCs without
the need of an additional interface card.

LOCATION OF CUSTOMER CONTROLS
6
1. Disc tray
This is the tray for the disc. Place the disc on the
ejected disc tray, then lightly push the tray (or
push the eject button) and the CD will be loaded.
NOTE: Don’t pull out or push in the disc tray
forcibly. This might cause damage to the loading
section of the drive.
2. Stop/Eject button
This button is pressed to open the CD tray.
This button works only when power is supplied to
the drive.
If an Audio CD is playing, pressing this button will
stop it, and pressing it again will open the tray.
3. Emergency Eject Hole
Insert a paper clip here to eject the Disc tray
manually or when there is no power.
4. Volume control
This is used to adjust the output volume of the
headphone jack. It can’t be used to adjust the
output volume for the audio output connectors on
the rear panel.
NOTE : Turn the volume down before turning on
the power. Sudden loud noises can damage your
hearing.
5. Headphone jack
This jack is for connecting headphones or mini-
speakers.
6. Drive activity indicators
Two colored LEDs are used to indicate the
operation of CD-R/RW Drive.
(1) Read
The orange color is displayed when the spindle
motor begins the Spin up operation: accessing
data, reading data, playing Audio, and up loading
tray.
(2) Write
The green color is flashed during disc writing
sessions.
READ
READ
WRITE
WRITE
Headphone Jack
Volume
Control Drive Activity Indicators
Stop/Eject Button
Disc Tray
Emergency Eject Hole
Front Panel

7
1. Power Connector
Connects to the power supply (5-and 12-V DC) of
the host computer.
NOTE : Be careful to connect with the proper
polarity. Connecting the wrong way may damage
the system (and is not guaranteed). Usually this
connector can only be attached one-way.
2. IDE Interface Connector
Connect to the IDE (Integrated Device
Electronics) Interface using a 40-pin flat IDE
cable.
NOTE : Do not connect or disconnect the cable
when the power is on, as this could cause a short
circuit and damage the system. Always turn the
power OFF when connecting or disconnecting the
cable.
3. Jumper Connector
This jumper determines whether the drive is
configured as a master or slave. Changing the
master-slave configuration takes effect after
power-on reset.
4. Analog Audio Output Connector
Provides output to a sound card (analog signal).
Generally you need this to play a regular audio
CD.
5. Digital Audio Output Connector
Provides output to a sound card (digital signal).
DIGITAL
AUDIO
ANALOG
AUDIO INTERFACE POWER
D G
39
40 1+5 GND +12
2
C S M
S L A
R G L
Digital Audio Output
Connector
Jumper Connector
Analog Audio Output Connector IDE Interface Connector
Power Connector
Rear Panel

1. CABINET and CIRCUIT BOARD
DISASSEMBLY
1-1. Bottom Chassis
A. Release 4 screws (A) and remove the Bottom Chassis
in the direction of arrow (1). (See Fig.1-1)
1-2. Front Bezel Assy
A. Insert and press a rod in the Emergency Eject
Hole and then the CD Tray will open in the direction
of arrow (2).
B. Remove the Tray Door in the direction of arrow
(3) by pushing the stoppers forward.
C. Release 3 stoppers and remove the Front Bezel Assy.
1-3. Cabinet and Main Circuit Board
A. Remove the Cabinet in the direction of arrow (4).
(See Fig. 1-3)
B. Release 2 hooks (a) and remove the CD Tray
drawing forward.
C. Remove the Main Circuit Board in the direction of
arrow (5).
D. At this time, be careful not to damage the 4
connectors, are positioned at right side, of the Main
Circuit Board.
2. MECHANISM ASSY DISASSEMBLY
2-1. Pick-up Unit
A. Release screws (B).
B. Separate the Pick-up Unit in the direction of arrow (6).
(4)
(5)
Main
Circuit Board
Cabinet
Hooks (a)
(A)
(A) (A)
(A)
(1)
Bottom Chassis
(2)
(3)
Tray Door
CD Tray
Front Bezel Assy
Emergency Eject Hole
Stoppers
Fig. 1-1
Fig. 1-2
DISASSEMBLY
8
Fig. 1-3
Mechanism Assy
Pick-up Unit (6)
(B) (B)
Fig. 2-1

2-2. Pick-up
A. Release 2 screws (C) and remove the Pick-up.
Pick-up Unit
Pick-up
(C)
(C)
Fig. 2-2
9

ATIP Absolute Time In Pre-groove.With an additional modulation of the “Wobble”,the “Groove”contains a
time code information
Wobble The pre-groove in the Disc is not a perfect spiral but is wobbled with ; - a typical amplitude of 30ns
- a spatial period of 54 -64µm
(Pre-) groove The guidance track in which clocking and time code information is stored by means of an FM
modulated wobble
CW Continuous Wave. The laser light output is at a constant level
DOW Direct Over-Write. The action in which new information is recorded over previously recorded
information in CD-RW disc.
Overwrite The action in which new information is recorded over previously recorded information
Land Land is characterized in the following way:
When radial signals are concerned,land is defined as the area between the groove
When HF signal are concerned,land is defined as the area between the marks(pits) in tangential
direction
Hybrid Disc A Multisession disc of which the first Session is mastered. On a hybrid disc, recorded and mastered
information may co-exist
Mastered Information Information,stored as pits on the disc during the manufacturing process of the disc (when making the
“master”)
OPC Optimum Power Control. Procedure is determined optimum recording power according to CD-R/RW
Media in recording start step.
ROPC Running OPC. The purpose is to continuously adjust the writing power to the optimum power that is
required
When the optimum power may change because of changed conditions of disc and change in
operating temperature,
Jitter The 1øvalue of the time variation between leading and trailing edges of a specific (Mark) pit or land
as measured by Time Interval Analysis
Deviation The difference between a fixed value of Pit length and Land length
TOC Table Of Contents : in the Lead-in Area the subcode Q-channel contains information about the Track
on the disc
Packet Writing A method of writing data on a CD in small increments.
Two kinds of packets can be written : Fixed-length and Variable-length
Write Strategy The shape of the HF write signal used to modulate the power of the laser. The Write Strategy must
be used for recordings necessary for disc measurements
Information Area Wobble, ATIP, Disc Identification, Write Power, Speed Range OPC Parameters, etc are recorded in
the Information area of CD-RW Disc
Finalization The action in which (partially) unrecorded or logically erased tracks are finished and the Lead-in
and/or Lead-out areas are recorded or overwritten with the appropriate TOC subcode
Logical Erase A method to remove information from a disc area by overwriting it with an EFM signal containing
mode 0 subco A logically erased area is equivalent to an unrecorded
Physical Erase The action in which previously recorded information is erased by overwriting with a CW laser output.
After a Physical Erase action ,the erased area on the CD-RW disc is in the unrecorded state again.
Session An area on the disc consisting of a Lead-in area ,a Program area,a Lead-out area.
Multi session A session that contains or can contain more than one session composed Lead-in and Lead-out
GLOSSARY
15

The differences of CD-R/CD-RW discs and General CD-ROM
1. Recording Layer
Recordable CD has a wobbled pre-groove on the surface of disc for laser beam to follow track.
2. Disc Specification
Read-only Disc
CD-R and CD-RW Disc
3~11T
1.6um
0.4~0.5 um
(Pit)Groove
Land
Track pitch(p)
Radial Direction
Iw
A
O
a
a
Groove
Land
Radial Error Signal
The Groove wobble
Average center
Actual center
16
CD-ROM (READ-ONLY DISC) a=30nm
ITEM CD-ROM CD-R CD-RW
Standard Yellow Book Orange Book II Orange Book III
Record Not available Write once Re-Writable
Tracking Signal I11/Itop > 0.6 > 0.6 0.55 > M11> 0.70
(HF Modulation)
Read Laser Power(mW) < 0.5 mW < 0.7 mW < 1.0 mW
Jitter < 35 nsec < 35 nsec < 35 nsec
Reflectivity (Rtop) 70 % 65 % 15 % ~ 25 %
Remark) Write Laser Power(mW) 14-65 mW 6-45 mW

17
3. Disc Materials
1) CD-ROM disc
Laser Beam Groove
Substrate
(Polycarbonate)
Organic Dye Layer
Reflective Layer
Protective Layer
Label Printing
2) CD-R disc
Pigment Reflective Layer Color
Phtalocyanine Gold/Silver Yellow/White
Cyanine Gold/Silver Dark Green/Bright Green
Azo Gold/Silver Dark Blue
•It is composed of Silver _ colored aluminum plate and Reflective layer.
•Groove (Pit) of aluminum plate make a track.
•Laser wavelength : 780 nm, Laser Power (Read): 0.5mW
•Signal is detected by the
difference of reflective beam
intensity between “pit”and
“Land”on the disc.
•It is so-called WORM (Write Once Read Many) CD.
•It is composed of polycarbonate layer, Organic dye layer, Reflective layer, and Protective
layer.Gold/Silver Reflective layer is used to enhance the reflectivity
•According to the kinds of Organic dye layer, it is divided by Green CD, Gold CD, Blue CD.
•Laser Wavelength : 780 nm, Laser Power (read) : 0.7 mW
•Recording Power : 8x(14~20mW), 12x(15~30mW), 16x(25~35mW), 48x(50~65mW)
•When some part of dye layer is exposed to laser heat, it’s color changs black.Therefore, writing and
reading is enabled by the difference of reflectivity between changed part and unchanged part.
•Polycarbonate layer has Pre_Groove which make a Track.
Laser Beam
Pit
Substrate
(Polycarbonate)
Reflective Layer
Protective Layer
Label Printing

18
3) CD-RW Disc
4. Reading process of Optical Disc
Laser Beam Groove
Substrate
(Polycarbonate)
Recording Layer
Dielectric Layer(TL)
Dielectric Layer(UL)
Protective Layer
Label Printing
•It is composed of polycarbonate layer, alloy(silver, arsenic) layer, aluminum reflectivity layer, protective layer.
•An crystalized alloy layer is transformed into noncrystalized by the laser heat. Therefore, writing and reading
is enabled by the difference of reflectivity.
•It is possible to overwrite about 1000 times.
•Laser Wavelength : 780 nm, Laser Power (Read) : 1.0mW
•Recording Power : Erase (4~18mW), Write (6~45mW)
•When disc rewriting, new data is overwritten previously recorded data.
•Polycarbonate layer has a Pre-Groove which make a track.
Lens H
D
Beam
Spot
Focusing
Lens
Laser Spot
at Constant
Read Intensity
Reflected
Light
Signal
Laser Spot
Position
(Time)
Previously Recorded Marks
Groove Land Mirror
I3Itop
I11 IGILI0
Numerical aperture: NA=nsin θ ,
n: Refractive index
Focus depth : H=
λ /NA
laser spot diameter : D=
λ /NA
2
θ

19
5. Writing Process of CD-R Disc
a b c d e f g
a
b
c
d
e
f
g
Incident
Laser
Power (Read) (Read)
(Write)
Laser Spot
Position
(Time)
a b c d e f g Laser Spot
Position
(Time)
Laser
Spot
Recorded
Mark
Reflected
Light
Signal
Reflected
Light
Signal
Below "ORP"–Mark Too Short
At Optimum Record Power ("ORP")
Above "ORP" –Mark Too Long
Time
6. Writing process of CD-RW Disc
Write Power
Erase Power
Read Power
Groove
Crystal Amorphous
Amorphous
Recorded state
(lower reflectivity)
Melting/
quenching
Heating/
gradual cooling
Crystal phase
Erased state
(higher reflectivity)

7. Organization of the PCA, PMA and Lead-in Area
1) Layout of CD-ROM disc
20
Center hole Clamping and Label Area Information Area
Lead-in Area
Lead-in Area
Diameter 15 mm
Diameter 46 mm
Diameter 120 mm
Program Area
Read Only Disc
Lead-out Area
Program Area Lead-out Area
Center hole Clamping and Label Area Information Area
PCA PMA
Test Area Count Area
Diameter 15 mm
Diameter 45 mm
Diameter 120 mm
Unrecorded Disc
Tsl-00:35:65 Tsl-00:15:05 Tsl-00:13:25 Tsl 99:59:74
00:00:00
in out
Test Area : for performing OPC procedures.
Count Area : to find the usable area immediately in T.A
Tsl : start time of the Lead-in Area, as encoded in ATIP
PMA : Program Memory Area
Disc Center
Disc Center
2) Layout of CD-R/RW disc

21
8. Function of PCA and PMA area
1) PCA (Power Calibration Area)
•PCA area is used to determine the correct Laser Power for a disc.
–Method 1 : PCA area is divided by a track.
–Method 2 : The previous Calibration value is referred to.
–Method 3 : ROPC is used to determine Laser Power value automatically in data writing.
•CD-R Disc can write maximum 99 Tracks but CD-RW Disc can write unlimited tracks because it has a rewritable
function.
2) PMA (Program Memory Area)
•It has a track information (track No, track Start/End time) of every track before writing completed.
–PMA area has the last written point and the next writable point of a disc.
–In case of CD to CD copy, some writer may not write PMA area.
* When Disc is Finalized,
PMA information is transferred to the Lead_In area so that general Driver can read it.
* Because PCA and PMA area exist before Lead-In area, General CD Player or CD-ROM Drive can’t read
these areas.
9. OPC and ROPC
1) OPC (Optimum Power Control)
•This is the first step of writing process, because CD writer has its own laser power value and media have different
writing characteristics,
–This is determined by the Writing characteristic, speed, temperature, and humidity.
–Laser wavelength is determined by the environmental temperature (775~795nm) and Optical Laser Power is
determined by the test and retry.
•Asymmetry and optimum writing Power
–EFM signal Asymmetry is determined by the writing power.
Therefore, Optical Power which has the same value to the preset power value can be estimated by measuring
HF signal Asymmetry on the PCA area.
•Measurement of Asymmetry
* Parameter setting (Beta) : Using AC coupled HF signal before equalization
Beta = (A1+A2)/(A1-A2)
Time P << Po Time P = Po
HF Signal
A1
0
A2
Time P >> Po

2) ROPC (Running Optimum Power Control)
•Variable primary factor of Optimum Power
–Change of Power sensitivity on the Disc. (limited to 0.05 *Po)
–Wavelength shift of the laser diode due to the operating temperature change.
–Change of the Spot aberration due to the Disc skew,
Substrate thickness, Defocus.
–Change of Disc or Optics conditions due to the long term OPC
==> It is necessary to adjust continuously to obtain the Optimum Power.
•Principle of Running OPC
–To meet the factors mentioned above,
a horizontal direction movement of a curve is uesd.
–Beta = f(B-level) = constant on the Recorded Disc
–Procedure of ROPC
a. Reference B-level is determined during OPC Procedure.
b. During Recording, B-level value is controlled to have a close
Reference B-level value.
c. Normalization of B-level is used to eliminate the effect of reflectivity fluctuation.
==> The reflected B-level value is normalized by the disc reflectivity itself.
22
CD-R/RW Media
Write Strategy
Determination
PCA Test Area
Program Area
PMA Area
Lead-In Area
Lead-out Area
OPC
PCA Count Area
ROPC
Incident recording pulse
Reflected recording pulse
Sampled timing B
11T
Sample B-level (Write Power)
Level B
Sampled at timing B
Pwo decided by OPC
Recording Power
Level Bwith Pwo
normalized to recording power
Sample Disc Reflectivity
(Read power)
10. Writing Process of DISC

23
11. Recording capacity of CD-R/RW (74min Recording media)
•(2048 Byte / Sector ) x ( 75 Sector / Second ) x ( 60 Second / Minute) x 74 Minute
= 681,984,000 Bytes = 682 Mbytes
•But the actual recording capacity is about 650 Mbytes. (according to the ISO 9660 standard,
approximately 30 Mbytes are used to make directory structure and volume names.)
12. Super Link
Super(SUPpressed Error Recording) link method is a new technology to link the interrupted recording by
buffer under run. When drive’s buffer will be under, the drive will stop recording and store the stop position.
When drive’s buffer receive data from HOST again, the drive will seek to the stop position of last recording
and continue writing. In the read procedure, the drive can not find any error in the linking area, the data or
audio will be regenerated perfectly.
13. Optimum record speed
To prevent record fail or readability problem of recorded disc, the drive should decide optimum recording
speed during the recording for the media.
1) All media do not support 48x recording by media quality. Even though a CD-R can be recorded by 48x,
there is a possibility to occur fail during recording, especially in high speed writing.
2) So during the recording, Drive checks the Atip and Servo errors, and Drive thinks the current recording
status is unstable, then decreases the recording speed for getting stable record.
3) Drive changes the write pulse and power for low speed CLV recording and continuously checks Atip and
Servo errors during recording.
Writing
Speed
32X
24X
16X
48 74 Time[min]
Normal Case
Speed Down Case
40X
48X
22 to 48X CAV(9540 RPM)

14. Full/Partial CAV & Zone CLV Recording Comparison
24
Full/Partial CAV Zone CLV
Advantage
Disadvantage
1. Reduce Recording time.
( no loss time for speed change )
2. Easy to Spindle RPM control
1. Increase a stability of Recording.
( 4 CLV zone : 16, 24, 32, 40x )
2. High Recording quality compare to P-CAV.
1. It is difficult to control servo
stability of CAV recording.
2. It has a difficulty in getting
the high Recording quality
relative to Zone CLV.
1. Recording time is longer than partial CAV.
2. It needs to control the spindle in speed
change area.
Data
transfer
rate
RPM
* Full/Partial CAV
16X
40X CLV
Time
CLV Speed change
Time
0
24X
32X
* Zone CLV
40X PCLV
Time
Spindle Mode Change
Time
0
9020
22x
9540 48x CAV
40x PCAV
20x
48X CAV

INTERNAL STRUCTURE OF THE PICK-UP
1. KRS-340B Circuit Diagram
25
1
2
3
4
5
6
7
1
2
3
4
5
1
2
3
4
5
6
7
8
9
10
11
12 13
14
15
16
17
18
19
20
21
22
23
24
14
13
12
11
10
9
8
10
9
8
7
6
R3
VR1
VR2
R2
C6
C4
C7
LD
C5
R4
R1
L1
R5
R6
C8
R7
C11 C10 C9
Vcc
2 Axis Actuator OP output terminal
IC1
CXA2660N
IC2
C1
C2C3
GND
G
D
C
E
RRF
WRF
GND
H
A
B
F
Vc
VLIM
GND
GNDGND
VccVc
BinOUT
PDIN
VOUT
VCC
VREF
VCC
GND
IOUT
IINR
IOUT
IIN2
GND
IIN3
GND
RFREQ
RAMP
GND
ENABLE
GND
OSCEN
WEN3
VCC
WEN2
GND
GND
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
6
5
4
3
2
1FCS +
FCS -
TRK +
TRK -
LIM
G
D
C
E
RRF
WRF
PDGND
PDVC
F
B
A
H
PDVCC
FPDO
FPDVCC
FPDGND
FPDVC
LDVCC
LDVCC
VRDC
VWDC1
VWDC2
LDGND
LDGND
WE1
WE2
OSCEN
33
34
ENBL
MODAMP
IC3
EL6215CU

2. Signal detection of the P/U
1) Focus Error Signal ==> (A+C)-(B+D)
This signal is generated in RF IC (IC401 : MT1516) and controls the pick-up’s up and down to focus on
Disc.
2) Tracking Error Signal (DPP Method) ==> {(A+D)-(B+C)}- k x {(F+H)-(E+G)}
This signal is generated in RF IC (IC401 : MT1516) and controls the pick-up’s left and right shift to find to
track on Disc.
3) RF Signal ==> (A+B+C+D)
This signal is converted to DATA signal in DSP IC (IC101 : MT1518).
26
Pick-Up module
Photo Diode Tracking
Focusing
Infrared Iaser
k[(F+H) - (E+G)]
(A+D) - (B+C)
(A+D) - (B+C) - k[(F+H) - (E+G)]
Offset
TE
Tp
Sub2
Main
Tp/2 Sub1
Track Center
F,E
D,C
A,B
H,G

DESCRIPTION OF CIRCUIT
1. ALPC (Automatic Laser Power Control) Circuit
1-1. Block Diagram
27
MT1518
Write
Strategy
Write
S/H Signal
Micro
Processor
IC 101
CN 201
IC 401 (
MT1516 )
Optical
Pick-up
KRS-340B
LD
Drive
19 54
65
FPDO
FPDOLP
6226
VWDC1O
VWDC1
6127
VWDC2O
VWDC2 127 58
WLDON
128 57
RLDON
6325
VRDCO
VRDC 112 71
RFPDSH
S/H &
VRDCG &
Level Shift
111
S/H &
VWDC1G &
Level Shift
VWDC1
DAC
& Gain
WFPDSH
72
WDAC2
&
Amplifier
WDAC1
& x1/x2
RDAC
VRDC
DAC
& Gain
22 52
FVREF
+
-
-
+
1-2. ALPC(Automatic Laser Power Control) Circuit Operation
ALPC function in CD-R/RW analog front-end is for constant power level control purpose.
Based on the accurate power sensor(FMD) in PU, APC feedback loop maintains constant power level against
laser diode¡fls temperature variation.
There are two power control loops in MT1516, which are used with different combination for different
applications. Generally, the first APC loop is used for read-power control. The 2nd APC loop is used for
write(erase) power control for CD-R(CD-RW) disc.
Owing to the small signal level in read-power control mode, the first APC loop amplifies (x5/x10/x15/20x) the
FMD signal(FPDO) to enhance the accuracy of read power control. The built-in 8-bit DAC(RDAC) is used to set
the read power level. Moreover, the 2nd APC loop is used for high power control. The built-in 10-bit
DAC(WDAC1) is used to set the wanted power level. And the register VWDC1G is employed to adjust the gain
of FMD signal.
The following potentiometers(VRDCDAC, VWDC1DAC, and WDAC2) and amplifiers(VRDCDAG, VWDC1DAG
and WDAC2G) are used to set the wanted levels of the output pins VRDCO, VWDC1O, and VWDC2O.
Moreover, the input signal FPDO after low-pass filtering & amplification(x1 or x2) will send the MPXOUT2 for
monitoring.

28
2. Focus Circuit
2-1. Block Diagram
Disc
Motor unit
Optical
Pick-up
KRS-340B
A,B,C,D
E,F,G,H
-{(A+C)-(B+D)}
HAVC
LS
to
V14 FEO
FEI
ADC
Focusing
Compensator
DAC
FRO
FRO
1.4V
R149
IC501
BD7907
C562
R560
IC505 R566
FCS+
FCS-
FCS+
FCS-
IC401
MT1516
IC101
MT1518
MUTE2
MUTE1
CTL1
CTL2
MUTE2
MUTE1
C188
VC 1.4V
FCIN
-((E+F+G+H))
LPF G
HAVC
LS
to
0.8V
SBAD
SBAD
49
LPF G
101
102
42
42
38
22
53
27
22
23
46
45
2-2. Focus Servo
The aim of Focus Servo is to maintain the distance between object lens of P/U and disc surface, so that the
detected RF signal(A, B, C, D, E, F, G, H) can be maximized.
Focus Error Signal(FE) generates from focus error detection block in RF IC(MT1516) using Astigmatism
Method.
Focus Gain and path can be changed at the RF IC(MT1516) according to the disc, and the resulting output
FE(MT1516 42pin) is input to DSP IC(MT1518 42pin).
The SBAD Signal(MT1516 49pin) is from the sum of Side Beam(E, F, G, H), represents Beam Strength and
input to DSP IC(MT1518 38pin).
The Focus Search operation is using FE, SBAD Signal, therefore check FE, SBAD signals when Focusing is
failed.
The role of DSP IC(MT1518) is Focus Digital Controller. The operation path is as follows;
FE Signal is input to DSP IC(MT1518 42pin), and after A/D Conversion, Digital Equalizer Block and D/A
Conversion in MT1518, the output signal FRO(MT1518 22pin) is input to Drive IC(BD7907 53pin).
The drive output signal FCS+/FCS- generated according FCIN(BD7907 53pin), and drives focus actuator in the
P/U unit.

3. Tracking & Sled Circuit
3-1-1. Block Diagram (Tracking Following)
Disc
Motor unit
Optical
Pick-up
KRS-340B
A,B,C,D
E,F,G,H
TEO
TEI
ADC
Tracking
Compensator
DAC
TRO
TRK+
TRK-
IC401
MT1516
IC101
MT1518
MUTE2
MUTE1
MPPO
(A+D)-(B+C)
G
HAVC
LS
to
V14
101
102
45
40
23
L
P
F
L
P
F
SPPO
K*{(F+H)-(E+G)}
Sled
Compensator
PWM
FMO
26
FMO2
27
A+
A-
B+
B-
SLED MOTOR
Unit
TRO
1.4V
R148
IC501
BD7907
C561
R561
IC505 R567
TRK+
TRK-
CTL1
CTL2
MUTE2
MUTE1
C187
VC
1.4V
TRKIN
52
27
22
23
46
45
FMO
28
FMO229
R148
R148
C154 C156
SLIN1
SLIN2
A+
A-
46
45
B+
B-
46
45
SLO1+
SL01-
SLO2+
SLO2-
29