LG CRD-8485B Service Manual
INTRODUCTION
This service manual provides a variety of service information. It contains the mechanical structure of the CD-ROM Drive together with mechanical adjustments and the electronic circuits in schematic
form. This CD-ROM Drive was manufactured and assembled under our strict quality control standards and meets or exceeds industry specifications and standards.
GENERAL FEATURE
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Enhanced IDE interface |
• Software Volume Control |
• Internal 5.25 inch, halfheight CD-ROM Drive |
• 8 Times Digital Filter for CD Audio |
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• Fast 75ms Average Access Time |
• Front panel Volume Control for Headphone Output |
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• Max 7,200KB/sec Sustained Transfer rate |
• Built-in MODE-1 ECC/EDC |
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• Photo-CD Multisession Disc Spec compliant |
• MTBF 125,000h POH (at 10% Utilization) |
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• Multimedia MPC-3 Spec compliant |
• PIO Mode 4 & Multi DMA Mode 2 support |
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• Power Tray Loading/Ejection Mechanism |
• Horizontal or Vertical Mounting |
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3 Way Eject support (Software, O/C Button, |
• Digital audio output connector |
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Emergency Eject) |
• Digital audio through ATAPI Interface |
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Closed Enclosure |
• Subcode (P-W) through ATAPI Interface |
• Built-in ATAPI Interface Controller |
• Spin-down Mode for energy saving |
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SPECIFICATIONS
1.SUPPORTED SYSTEM
•IBM Compatible 486SX or Above (With PIO mode 4 recommended)
2.SUPPORTED OS
• MS-DOS Version 3.1 or Higher |
• Solaris Ver 2.4 or Higher |
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OS/2 Warp (Ver 3.0) |
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Linux slackware Ver 2.3 |
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Windows '95/'98 |
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Windows NT 4.0 or later |
3. GENERAL PERFORMANCE
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Data Transfer Rate.......................................................................................... |
Sustained Data Transfer Rate |
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20Times Speed (Inner side) : 3,000 kbytes/sec |
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48 Times Speed (max., Outer side) : 7,200 kbytes/sec |
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Data Buffer Capacity ..................................................................................................................... |
128 kbytes |
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Access Time ................................................................................................... |
Random Access Time : 75 ms |
4. POWER REQUIREMENTS
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Voltage |
.......................................................................................................................................+5V DC |
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5% |
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+12V DC |
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5% |
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Ripple................................................................................................................... |
+5V : Less than 100mVp-p |
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+12V : Less than 100mVp-p |
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Current........................................................................................................................ |
+5V : 0.9A (Maximum) |
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+12V : 1.5A (Maximum) |
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5. AUDIO PERFORMANCE
• Frequency Response ..................................................................................................... |
20Hz~20KHz( |
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3dB) |
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• S/N Ratio (IHF-A+20 KHz LPF)........................................................................ |
85 dB (Typical at 1 |
KHz 0dB) |
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80 dB (Limit at 1 |
KHz 0dB) |
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• T.H.D. (IHF-A+20 KHz LPF) ............................................................................ |
0.05% (Typical at 1 |
KHz 0dB) |
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0.15% (Limit at 1 |
KHz 0dB) |
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• Channel Separation (IHF-A+20 KHz LPF).............................................................................. |
80 dB (Typical) |
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70 dB (Limit) |
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• Output Voltage (1kHz 0dB) 47KΩ Load ................................................................................. |
0.7Vrms + 10% |
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• Headphone Level (1kHz 0dB) 33Ω Load ............................................................................... |
0.7Vrms + 20% |
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LOCATION OF CUSTOMER CONTROLS
FRONT
COMPACT
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Figure 1. Front View
(1)Headphone Jack
3.5mm jack for monitoring the audio signal from audio CDs.
(2)Headphone Volume Control
Adjusts the headphone sound level.
(3)Disc Drawer
Accepts a CD-ROM disc on its tray.
(4)Busy Indicator
The Busy Indicator lights during initialization and dataread operations.
(5)Emergency Eject Hole
Insert a paper clip here to eject the drawer manually or when there is no power.
(6)Play/Skip Button
When an Audio CD is in the Disc Drawer, pressing this button will start playing audio CDs from the first track. If an audio CD is playing, pressing this button will skip to the next track.
(7)Open/Close/Stop Button
This button is pressed to open or close the CD tray.
If an audio CD is playing, pressing this button will stop it, and pressing it again will open the tray.
REAR
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DIGITAL |
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ANALOG |
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INTERFACE |
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POWER |
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AUDIO |
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AUDIO |
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+5 |
GND +12 |
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D G |
R G L C S M |
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S L A |
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Figure 2. BackView
(1)Digital Audio Output Connector
This is a digital audio output connector or Video CD output connector.
You can connect this to the digital audio system or Video CD Board.
(2)Analog Audio Output Connector
The Audio Output Connector connects to a sound card.
The supplied audio cable is a SoundBlaster® type cable. If you have a different sound card, you will need to contact the sound card manufacturer to obtain the proper cable for that card.
(3)Master / Slave / CSEL Jumper
These three jumpers are used to set the CD-ROM Drive to either a Master, Slave, or CSEL drive.
(4)Interface Connector
This 40-pin connector is used to transfer and control signals between the CD-ROM Drive and your PC. Connect the 40-pin IDE cable in your PC to this connector.
(5)Power-in Connector
Attach a power cable from the computer to this connector.
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TROUBLESHOOTING GUIDE
1. Initial Lead-in Operation
Reset or Power-On.
LED Flickers.
Pick-Up moves to the inner-Track.
Laser on the Pick-Up lights.
Focus Search (through moving up and down the lens of Pick-Up)
Focus Servo On (FEO(IC501 Pin 12 ) signal generation)
Rotate disc.
Tracking Servo On (TEO (IC501 Pin 15 ) Signal generation)
Spindle Servo On (DMSO(TP25) Signal generation)
Read TOC Area (LED Flickers)
Search the Start of Data Area and then pause.
2.Trouble List (Circuit)
A.LED doesn’t light.
B.Pick-Up doesn’t move to the inner-track.
C.The Laser of Pick-Up doesn’t light.
D.Pick-Up lens doesn’t move up and down.
E.Disc doesn’t rotate.
F.TOC isn’t read. (The LED turns on, but doesn’t flicker.)
G.During Audio CD Play, LED flickers, but Speaker is silent.
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3. Troubleshooting Guide
A. LED doesn’t light.
Check Power Voltage (TP1:3.3V, TP2:12V)
Reference Voltage
[TP5:V13(1.3V) and GND.]
OK
Does “H” output in IC501 pin 37 ?
YES
Check and replace R705, R706, Q701 and LED701 (LED703 for DELL).
NG
NO
Check the power input pattern.
Is the CLOCK Frequency of |
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NO |
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A-1 |
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IC501 pin 54 33.86MHz? |
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YES |
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Check IC501.
A
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Is the CLOCK Frequency of IC501 pin 54 |
NO |
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Check and replace |
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33.86MHz? |
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X501; 33.86MHz. |
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YES
Check and replace IC501.
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B. Pick-Up doesn’t move to the inner track.
Do the signals appear at IC501 pin 173 , 174?
(Refer to Fig. B-1.)
YES
Does “H” output at IC201 pin 41 ?
YES
Is the 1.3V at IC201 pin 25 ?
YES
Do the signals appear in PN301 pin?
(Refer to Fig. B-2.)
YES
Check the PN301, and then replace the Sled Motor.
CH1
PIN174
FMO
CH2
PIN173 
FMO2
NO
Check IC501.
NO |
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Check the pattern from |
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IC501 pin 165 to IC201 |
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pin 41 . |
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NO
Check IC501.
NO
Replace IC201.
CH1 TP4 
CH2 TP5
CH3 TP6 
CH4 TP7 
Fig. B-1. FMO and FMO2 Signals |
Fig. B-2. TP4, TP5, TP6 and TP7 Signals |
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C. The Laser of Pick-Up doesn’t light.
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NO |
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Is the voltage of IC501 pin 10 |
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Check Q101, C101, C102 |
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(LD0) 1V? |
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and then replace IC101. |
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YES |
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Check Pick-Up FFC, PN101.
D. The Pick-UP lens doesn’t move up and down.
Does the focus search signal appear at F0S0 (TP9)? (Refer to Fig. D-1.)
YES
Is the 1.3V at IC201 pin 25 ?
YES
Does the focus search signal appear between F+ (TP10) and F- (TP11)?
(Refer to Fig. D-2.)
YES
NO |
Check the pattern from |
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IC501 pin 181 to R225 |
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and then replace IC501. |
NO
Check IC501.
NO
Replace IC201.
D
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D
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Check the pattern from pin 34 , 35 of IC201 to pin 1 , 4 of PN101.
OK
Check the PN101, Pick-Up
FFC.
OK
Replace the Pick-Up.
CH1
TP9
(FAO)
NG Replace PN101 or Pick-Up
FFC.
CH1
TP10(F+) 
TP11(F-)
Fig. D-1. F0S0 Signal |
Fig. D-2. Focus Search Signal |
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E. Disc doesn’t rotate.
Does the signal appear at NO F+ (TP10) during focus 
search?
YES
Do the signal appear at NO FEO (IC501 pin 12 )?
(Refer to Fig. E-2.)
YES
Does the signal appear at |
NO |
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FEO(IC501 pin 12 ) when |
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Replace Pick-Up. |
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the R126 opened? |
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(Refer to Fig. E-1.) |
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YES |
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Replace IC501. |
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Replace IC501.
Does the signal appear at the DMS0 (TP25)? (Refer to Fig. E-3.)
YES
Do the signals appear at IC201 pin 12 (W), 13 (V), and 14 (U)?
YES
Check the pattern from IC201 pin 12 , 13 , 14 to PN201 13 , 12 , 11 .
OK
Check Spindle Motor FFC
and then replace the
Spindle Motor.
NO
Replace IC501.
NO
Replace IC201.
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