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Dell GCR-8481B Service Manual

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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
• Enhanced IDE interface
• Internal 5.25 inch, halfheight CD-ROM Drive
• Fast 75ms Average Access Time
• Max 7,200KB/sec Sustained Transfer rate (GCR-8481B)
• Max 7,800KB/sec Sustained Transfer rate (GCR-8521B)
• Photo-CD Multisession Disc Spec compliant
• Multimedia MPC-3 Spec compliant
• Power Tray Loading/Ejection Mechanism
• 3 Way Eject support
(Software, O/C Button, Emergency Eject)
• Closed Enclosure
1. MODEL: GCR-8481B
1) SUPPORTED SYSTEM
• IBM Compatible 486SX or Above (With PIO mode 4 recommended)
2) SUPPORTED OS
• MS-DOS Version 3.1 or Higher
• Windows '95/'98/'2000/Me/XP
3) GENERAL PERFORMANCE
• Data Transfer Rate .........................................................................................Sustained Data Transfer Rate
• Data Buffer Capacity.....................................................................................................................128 kbytes
• Average Access Time ........................................................................Random Access Time : 75 ms Typical
4) POWER REQUIREMENTS
• Voltage ......................................................................................................................................+5V DC +5%
• Ripple ..................................................................................................................+5V : Less than 100mVp-p
• Current .......................................................................................................................+5V : 0.9A (Maximum)
5) AUDIO PERFORMANCE
• Frequency Response.....................................................................................................20Hz~20KHz(+3dB)
• S/N Ratio (IHF-A+20 KHz LPF) .......................................................................80 dB (Typical at 1 KHz 0dB)
• T.H.D. (IHF-A+20 KHz LPF) ............................................................................0.05% (Typical at 1 KHz 0dB)
• Channel Separation (IHF-A+20 KHz LPF) .............................................................................80 dB (Typical)
• Output Level (1kHz 0dB) 47KΩ Load ....................................................................................0.7Vrms + 10%
• Headphone Level (1kHz 0dB) 33Ω Load...............................................................................0.7Vrms + 20%
INTRODUCTION
GENERAL FEATURE

SPECIFICATIONS

• Solaris Ver 2.4 or Higher
• Linux slackware Ver 2.3
form. This CD-ROM Drive was manufactured and
assembled under our strict quality control standards
and meets or exceeds industry specifications and
standards.
• Built-in ATAPI Interface Controller
• Software Volume Control
• 8 Times Digital Filter for CD Audio
• Built-in MODE-1 ECC/EDC
• MTBF 125,000h POH (at 10% Utilization)
• PIO Mode 4 & Multi DMA Mode 2 support
• Horizontal or Vertical Mounting
• Digital audio output connector
• Digital audio through ATAPI Interface
• Subcode (P-W) through ATAPI Interface
• Spin-down Mode for energy saving
• Windows NT 4.0 or later
• OS/2 Warp (Ver 3.0)
20Times Speed (Inner side) : 3,000 kbytes/sec
48 Times Speed (max., Outer side) : 7,200 kbytes/sec
+12V DC +5%
+12V : Less than 100mVp-p
+12V : 1.5A (Maximum)
75 dB (Limit at 1 KHz 0dB)
0.15% (Limit at 1 KHz 0dB)
70 dB (Limit)
3

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  Summary of Contents for Dell GCR-8481B

  • Page 1: Specifications

    • Software Volume Control • Fast 75ms Average Access Time • 8 Times Digital Filter for CD Audio • Max 7,200KB/sec Sustained Transfer rate (GCR-8481B) • Built-in MODE-1 ECC/EDC • Max 7,800KB/sec Sustained Transfer rate (GCR-8521B) • MTBF 125,000h POH (at 10% Utilization) •...
  • Page 2: General Performance

    2. MODEL: GCR-8521B 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/’2000/Me/XP •...
  • Page 3: Block Diagram

    BLOCK DIAGRAM CXA2581N RF Amp. 33.86MHz Optical Disc Pick-up Motor unit 40MHz CXD3045R I/F Cable SPINDLE FOCUS TRACKING SLED LOADING DSP + Decoder + MOTOR COIL COIL MOTOR MOTOR DRAM + System controller M63026FP MOTOR DRIVE R-ch AUDIO L-ch Circuitry 3.3V Reg +3.3V Line-out...
  • Page 4: Troubleshooting Guide

    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 :H, FEO(TP15) signal generation) Rotate disc.
  • Page 5 3. Troubleshooting Guide A. LED doesn’t light. Check Power Voltage Check the power input (TP1:3.3V, TP20:2.5V, TP2:12V) pattern. Reference Voltage [TP3:DVC(1.35V) and GND.] Is the CLOCK Frequency of Does “H” output in IC501 IC501 pin 33.86MHz? Check and replace R705, Check IC501.
  • Page 6 B. Pick-Up doesn’t move to the inner track. Do the signals appear at IC501 pin Check IC501. (Refer to Fig. B-1.) Check the pattern from Does “H” output at IC201 IC501 pin to IC201 Check the R190 and Is the 1.35V at IC201 pin then replace IC102.
  • Page 7 C. The Laser of Pick-Up doesn’t light. Does “Low” or “High” Check R118 and replace output at IC102 pin IC501. Is the voltage of IC102 pin Check Q101, C101, C102 (LD) 2V? and then replace IC102. Check Pick-Up FFC, PN101. D.
  • Page 8 Check the pattern from of IC201 to of PN101. Replace PN101 or Pick-Up Check the PN101, Pick-Up FFC. FFC. Replace the Pick-Up. TP10(F+) TP11(F-) (FAO) Fig. D-1. FAO Signal Fig. D-2. Focus Search Signal...
  • Page 9 E. Disc doesn’t rotate. Does the signal appear at Does the signal appear at FOK (TP18) during focus FEO (TP15) when the Replace Pick-Up. search? R504 opened? (Refer to Fig. E-1.) (Refer to Fig. E-2.) Replace IC501. Do the signal appear at TP15 (FEO) and TP19 Replace IC501.
  • Page 10 TP10: TP15: S-Curve TP18: Fig. E-1. FOK, F+ Signal Fig. E-2. S-Curve (R505:Open) TP15: TP25: Fig. E-3. FEO Signal Fig. E-4. MDP Signal...
  • Page 11 F. TOC isn’t read. Is the Focus Servo ON? Does A, B, C, D signal (Does FEO (TP15) signal appear at IC102 pin appear?) Replace IC102. Refer to C. (The Laser of Pick-Up Is the Tracking Servo ON? Does E, F signal appear doesn’t light.) (Does TEO (TP14) signal at IC102 pin...
  • Page 12 G. During Audio CD play, LED flickers, but Speaker is silent. Does PWM signal appear at Replace IC501. IC501 pin 166 167 174 175 (Refer to Fig. G-1.) Does Audio signal appear Is the voltage of IC601 Check the R602. at IC601 pin 2.5V? (Refer to Fig.
  • Page 13 Is the connection between JK801 (or Audio Check the JK801 and Line out connector) and Audio line pattern. Line (or Jack) normal? Check your sound card, Audio Cable, Speaker, Volume and Headphone Jack. PIN6 of PIN3 of IC601 IC601 PIN10 of IC601 PIN12 of IC601...
  • Page 14 PHOTO DIODE STRUCTURE OF THE PICK-UP (1) Focus Error Signal –> (A+C)-(B+D) (Control the Pick-up’s up and down to focus on the Disc) (2) Tracking Error Signal –> (E-F) (Control the Pick-up’s left and right shift to find the track on the Disc) (3) RF Signal –>...
  • Page 15 IC INTERNAL BLOCK DIAGRAM AND PIN DESCRIPTION • IC102 (CXA2581N) : RF Amplifier IC I-V converts and amplifies the signal received from the pick-up and then applies to DSP part of one- chip IC (IC501). Block Diagram AC_SUM EQ_IN Pin Description Pin No.
  • Page 16 • IC201 (M63026FP) : Drive IC (Spindle/Servo Actuator) Rotates the Spindle Motor by receiving MDP signal from IC501. Generates the signal to drive Focus Actuator Coil, Tracking Actuator Coil, Sled Motor, and Stepping Motor by Control Signal input from DSP and u-COM. Block Diagram 023/026 FG x1 024/027 FG x3...
  • Page 17 • IC501 (CXD3045R) : DSP+ATAPI DECODER+DRAM+µ-COM Block Diagram * is connected to µ-com port inside. D0~7* A0~6* XRD* XWR* XCS* XINT* XWAT* PWM2N PWM2P PWM1N PWM1P DOUT MIRR DFCT BSSD...
  • Page 18 • IC501 CXD3045R Pin Description Pin No. Symbol COMMENT AVS6 Analog GND Analog DAC Analog Output of Slide Filter Analog DAC Analog Output of Tracking Filter Analog DAC Analog Output of Focus Filter BSSD Constant Current Input for DAC Analog of Servo Filter AVD6 Analog Power Supply (2.5V) VSIO0...
  • Page 19 Pin No. Symbol COMMENT AVD2 Analog Power Supply (2.5V) IGEN Resistor Connection Pin of Current Source Reference for OP Amp AVS2 Analog GND ADIO Analog OP Amp Output RFDC RF Signal Input Center Servo Analog Input Tracking Error Signal Input Slide Error Signal Input Focus Error Signal Input Center voltage Input...
  • Page 20 Pin No. Symbol COMMENT Internal DRAM Exclusive GND VSIO2 Digital GND VDIO2 Digital Power Supply (3.3V) (Port F) PF7/T2 16 bit capture timer/counter Output port IN/Output port as 1 bit PF6/T1 8 bit timer/counter Output port Internal DRAM Exclusive Power Supply Internal DRAM Exclusive GND (Port F) IN/Output port as 1 bit...
  • Page 21 Pin No. Symbol COMMENT VDIO3 Digital Power Supply (3.3V) OEXTAL Crystal Oscillating Circuit Output for the Master Clock EXTAL Crystal Oscillating Circuit Intput for the Master Clock VDIO4 Digital Power Supply GND RSTZ System Reset,“L” is reset XPDI Passed Diagnostics Signal, Open Drain Output, Negative Logic DASP Drive Active/Slave Present Signal, Open Drain Output, Negative Logic HCS1...
  • Page 22 Pin No. Symbol COMMENT HDBA 1,Z,0 Host Data Bus HDB5 1,Z,0 Host Data Bus VSIO7 Digital Power Supply GND HDB9 1,Z,0 Host Data Bus HDB6 1,Z,0 Host Data Bus HDB8 1,Z,0 Host Data Bus HDB7 1,Z,0 Host Data Bus VDC5 Digital Power Supply (2.5V) XTL2 1, 0...
  • Page 23: Cabinet And Circuit Board Disassembly

    DISASSEMBLY 1. CABINET and CIRCUIT BOARD 1-3. Cabinet and Main Circuit Board A. Remove the Cabinet in the direction of arrow (4). DISASSEMBLY (See Fig. 1-3) 1-1. Bottom Chassis B. Release 2 hooks (a) and remove the CD Tray. A. Release 4 screws (A) and remove the Bottom C.
  • Page 24 EXPLODED VIEW PBM00 (MAIN C.B.A)