LG CRD-8401B, CRD-8481B 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

•	Enhanced IDE interface	• Closed Enclosure
• Internal 5.25 inch, halfheight CD-ROM Drive		• Built-in ATAPI Interface Controller
• Fast 75ms Average Access Time		• Software Volume Control
• Max 7,200KB/sec Sustained Transfer rate		• 8 Times Digital Filter for CD Audio
•	CRD-8481B: Max 7,200 KB/sec Sustained	• Front panel Volume Control for Headphone Output
	Transfer rate	• Built-in MODE-1 ECC/EDC
•	CRD-8401B: Max 6,000 KB/sec Sustained	• MTBF 125,000h POH (at 10% Utilization)
	Transfer rate	• PIO Mode 4 & Multi DMA Mode 2 support
• Photo-CD Multisession Disc Spec compliant		• Horizontal or Vertical Mounting
• Multimedia MPC-3 Spec compliant		• Digital audio output connector
• Power Tray Loading/Ejection Mechanism		• Digital audio through ATAPI Interface
• 3 Way Eject support		• Subcode (P-W) through ATAPI Interface
	(Software, O/C Button, Emergency Eject)	• Spin-down Mode for energy saving

SPECIFICATIONS

1.MODEL: CRD-8481B

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	•	Windows NT 4.0 or later
• Windows '95/'98	•	Linux slackware Ver 2.3	•	OS/2 Warp (Ver 3.0)

3) GENERAL PERFORMANCE

• Data Transfer Rate .........................................................................................	Sustained Data Transfer Rate
	20Times Speed (Inner side) : 3,000 kbytes/sec
	48 Times Speed (max., Outer side) : 7,200 kbytes/sec
• Data Buffer Capacity.....................................................................................................................	128 kbytes
• Access Time...................................................................................................	Random Access Time : 75 ms

4) POWER REQUIREMENTS

• Voltage	......................................................................................................................................+5V DC +5%
	+12V DC +5%
• Ripple ..................................................................................................................	+5V : Less than 100mVp-p
	+12V : Less than 100mVp-p
• Current .......................................................................................................................	+5V : 0.9A (Maximum)
	+12V : 1.5A (Maximum)

5) AUDIO PERFORMANCE

• Frequency Response.....................................................................................................	20Hz~20KHz(+3dB)
• S/N Ratio (IHF-A+20 KHz LPF) .......................................................................	85 dB (Typical at 1	KHz 0dB)
	80 dB (Limit at 1	KHz 0dB)
• T.H.D. (IHF-A+20 KHz LPF)............................................................................	0.05% (Typical at 1	KHz 0dB)
	0.15% (Limit at 1	KHz 0dB)
• Channel Separation (IHF-A+20 KHz LPF) .............................................................................	80 dB (Typical)
	70 dB (Limit)
• Output Voltage (1kHz 0dB) 47KΩ Load.................................................................................	0.7Vrms + 10%
• Headphone Level (1kHz 0dB) 33Ω Load...............................................................................	0.7Vrms + 20%

2.MODEL: CRD-8401B

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
• OS/2 Warp (Ver 3.0)	•	Linux slackware Ver 2.3
• Windows '95/'98	•	Windows NT 4.0 or later

3) GENERAL PERFORMANCE

• Data Transfer Rate .........................................................................................	Sustained Data Transfer Rate
	18Times Speed (Inner side) : 2,700 kbytes/sec
	40 Times Speed (max., Outer side) : 6,000 kbytes/sec
• Data Buffer Capacity.....................................................................................................................	128 kbytes
• Access Time...................................................................................................	Random Access Time : 75 ms

4) POWER REQUIREMENTS

• Voltage	......................................................................................................................................+5V DC +5%
	+12V DC +5%
• Ripple ..................................................................................................................	+5V : Less than 100mVp-p
	+12V : Less than 100mVp-p
• Current .......................................................................................................................	+5V : 0.9A (Maximum)
	+12V : 1.5A (Maximum)

5) AUDIO PERFORMANCE

• Frequency Response.....................................................................................................	20Hz~20KHz(+3dB)
• S/N Ratio (IHF-A+20 KHz LPF) .......................................................................	85 dB (Typical at 1	KHz 0dB)
	80 dB (Limit at 1	KHz 0dB)
• T.H.D. (IHF-A+20 KHz LPF)............................................................................	0.05% (Typical at 1	KHz 0dB)
	0.15% (Limit at 1	KHz 0dB)
• Channel Separation (IHF-A+20 KHz LPF) .............................................................................	80 dB (Typical)
	70 dB (Limit)
• Output Voltage (1kHz 0dB) 47KΩ Load.................................................................................	0.7Vrms + 10%
• Headphone Level (1kHz 0dB) 33Ω Load...............................................................................	0.7Vrms + 20%

LOCATION OF CUSTOMER CONTROLS

FRONT

COMPACT

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

DIGITAL

ANALOG

INTERFACE

POWER

AUDIO

GND +12

D G

R G L C S M

S L A

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.

DISASSEMBLY

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)

(A)

Bottom Chassis

(A)

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 it outward.

C.Release 3 stoppers and remove the Front Bezel Assy.

Tray Door

(3)

Stoppers

(2)

CD Tray

Front Bezel Assy

Emergency Eject Hole

Fig. 1-2

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.

C.Remove the Soldering of the LDand LD+ (B) for the Loading Motor, and then remove the Main Circuit Board.

D.At this time, be careful not to damage the 3 connectors of the Main Circuit Board.

Cabinet

(4)

Hooks (a)

(B)

Main

Circuit Board

Fig. 1-3

2. MECHANISM ASSY

A.Separate the Pick-Up Unit from the Mechanism Assy.

B.Release 1 screws (C) and then remove the Pick-

Up (	).
	(C)
Pick-up Unit
	Mechanism Assy
	Fig. 1-4

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 (FOK Port : H, FEO(TP15) signal generation)

Rotate disc.

Tracking Servo On (TEO(TP14) Signal generation)

Spindle Servo On (MDP(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.

3. Troubleshooting Guide

A. LED doesn’t light.

Check Power Voltage

(TP1:3.3V, TP2:12V, TP20:2.7V) NG

Reference Voltage

[TP3:DVC(1.35V) and GND.]

Does “H” output in IC501 pin 109 ?

Check the power input pattern.

Is the CLOCK Frequency of	NO
	NO	A-1

IC501 pin 171 33.86MHz?
IC501 pin 171 33.86MHz?

YES

Check and replace R705,

R706, Q701 and LED701 Check IC501. (LED703 for DELL).

A-1

Is the CLOCK Frequency		NO	Check and replace
Is the CLOCK Frequency			X501; 33.86MHz,
of IC501 pin 171	33.86MHz?		X501; 33.86MHz,
of IC501 pin 171	33.86MHz?		X502: 40MHz
			X502: 40MHz

	YES