Dell Precision WorkStation 420 Service Manual
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Dell Precision WorkStation 420 Service Manual

Dell Precision WorkStation 420 Service Manual

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Dell Precision™ WorkStation 420 Systems Service Manual
Desktop Chassis — Removing and Replacing Parts
Mini Tower Chassis — Removing and Replacing Parts
NOTE: You can obtain the latest version of this document from the Support section of the Dell Web site at http://www.dell.com.
Notes, Notices, and Cautions
Throughout this guide, blocks of text may be accompanied by an icon and printed in bold type or in italic type. These blocks are notes, notices,
and cautions, and they are used as follows:
NOTE: A NOTE indicates important information that helps you make better use of your system.
NOTICE: A NOTICE indicates either potential damage to hardware or loss of data and tells you how to avoid the problem.
CAUTION: A CAUTION indicates a potentially hazardous situation which, if not avoided, may result in minor or moderate
injury.
Information in this document is subject to change without notice.
© 1999 Dell Computer Corporation. All rights reserved.
Reproduction in any manner whatsoever without the written permission of Dell Computer Corporation is strictly forbidden.
Trademarks used in this text: Dell, Dell Precision, and the DELL logo are trademarks of Dell Computer Corporation.
Other trademarks and trade names may be used in this document to refer to either the entities claiming the marks and names or their products.
Dell Computer Corporation disclaims any proprietary interest in trademarks and trade names other than its own.
Initial release: 30 Nov 1999

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Summary of Contents for Dell Precision WorkStation 420

  • Page 1 Desktop Chassis — Removing and Replacing Parts Mini Tower Chassis — Removing and Replacing Parts NOTE: You can obtain the latest version of this document from the Support section of the Dell Web site at http://www.dell.com. Notes, Notices, and Cautions Throughout this guide, blocks of text may be accompanied by an icon and printed in bold type or in italic type.

  • Page 2: Recommended Tools

    Expansion-Card Guide System Board Overview This section provides procedures for removing and replacing the components, assemblies, and subassemblies in the Dell Precision WorkStation 420 desktop chassis system. Unless otherwise noted, each procedure assumes that the following conditions exist: You have performed the steps in "Precautionary...

  • Page 3: Restarting The System

    the power supply, to discharge any static charge from your body before touching anything inside the computer.  While you work,  periodically touch an unpainted metal surface on the computer chassis to dissipate any static electricity that might harm internal components. Also avoid touching components or contacts on a card and avoid touching pins on a chip. 5. Verify that the standby power light-emitting diode (LED) on the system board is not on. If it is on, you may need to wait 10 to 30 seconds for it to go out (see Figure 22 or the internal service label).

  • Page 4: Interior Service Label

    1 Securing buttons (2) To replace the computer cover, perform the following steps: 1. Check all cable connections, especially those that might have come loose during your work. Fold cables out of the way so that they do not catch on the computer cover. Make sure cables are not routed over the drive bracket—they will prevent the cover from closing properly. 2.

  • Page 5: Front-Panel Inserts

    Expansion Cards The Dell Precision 420 systems provide five 32-bit Peripheral Component Interconnect (PCI) expansion card slots. Slot 5 is shared with the RAID port function. The system contains five 32-bit expansion slots and a 32-bit AGP Pro 50 (4X) slot. If you use an AGP Pro 50 card, it occupies the AGP slot and Figure 6...
  • Page 6 1 32-bit PCI expansion card 2 32-bit AGP card Figure 7. AGP Pro50 Card Extension Figure 7 shows the card extension that may occupy PCI slots 1 and 2. The following is a list of valid expansion-card combinations: One AGP card and five PCI cards One AGP card, four PCI cards, and one RAID card One AGP Pro50 card and four PCI cards One AGP Pro50 card, three PCI cards, and one RAID card...

  • Page 7: Expansion-Card Guide

    NOTE: If a setup password has been assigned by someone else, contact your network administrator for information on resetting the chassis intrusion detector. Expansion-Card Guide Figure 8. Expansion-Card Guide Removal 1 Left tabs (2) 2 Right tabs (2) To remove the expansion-card guide, perform the following steps: Remove the hard-disk drive bracket.

  • Page 8: Chassis Intrusion Switch

    1. Disconnect the control panel cable from the PANEL connector on the system board (see Figure 22 for the location of the PANEL connector). 2. Remove the mounting screw that secures the control panel to the chassis. 3. Disconnect the chassis intrusion switch cable connector from the control panel. 4.
  • Page 9 NOTE: In all of the following procedures, left and right refer to your left and right as you face the front of the computer. Figure 11. Drive Locations 1 Hard-disk drives 2 5.25-inch  drives  (CD-ROM drive shown) 3 3.5-inch diskette drive Diskette Drive Removal CAUTION: Before you remove the computer cover, see "Precautionary...
  • Page 10 1 3.5-inch diskette drive 2 Retaining tabs (2) 3 Bracket 4 Screw 6. Rotate the left side of the diskette drive up until the drive is clear of the retaining tabs. When you replace the 3.5-inch diskette drive on the bracket, be sure that the two retaining tabs on the right side of the bracket engage the mounting holes in the side of the 3.5-inch diskette drive.
  • Page 11 1 Metal tab 2 Drive bracket 3 Screws (4) Hard-Disk Drive Bracket Removal To remove the hard-disk drive bracket, perform the following steps. NOTICE: If you are removing a hard-disk drive that contains data you want to keep, be sure you have a backup of your files before you begin this procedure.
  • Page 12 CAUTION: Before you remove the computer cover, see "Precautionary Measures." 1. Remove the four screws that secure the hard-disk drive to the drive bracket. Retain these screws; they will be needed for the replacement drive. 2. Remove the hard-disk drive. Hard-Disk Drive Replacement To install a replacement hard-disk drive, perform the following steps.
  • Page 13 1 Screw 2 Hooks (3) 3 Drive bracket 4 Latch 8. Connect a DC power cable to the power input connector on the back of the drive (see Figure 19). Check all connectors to be certain that they are properly cabled and firmly seated. 9.

  • Page 14: Power Supply

    15. Test the hard-disk drive by running the Dell Diagnostics (see the online System User's Guide for more information). 16. If the drive you just installed is the primary drive, install your operating system on the hard-disk drive. Refer to the documentation that came with your operating system.

  • Page 15: System Board Components

    4. Rotate the power supply up and out of the way of the system board (see Figure 20). 5. Disconnect the power supply connectors from the POWER_1 and POWER_2 connectors on the system board. 6. Carefully fold the DC power supply cables you have disconnected and place them outside the chassis. 7.
  • Page 16 22 Auxiliary hard-disk drive access LED connector 23 PCI expansion slots 24 AGP graphics slot 25 Remote wakeup on LAN connector 26 Primary processor 0 socket 27 Network cable connector 28 Diagnostic LEDs 29 USB connectors 30 Secondary processor 1 socket 31 Line-in connector 32 Line-out connector 33 Microphone Connector...
  • Page 17 System Board Labels Table 2 lists the labels for connectors and sockets on your system board, and it gives a brief description of their functions. Table 2. System Board Connector and Socket Labels Connector or Socket Label Description AGP graphics card slot AUX_LED Hard-disk drive LED connector Battery...
  • Page 18 CAUTION: Before you remove the computer cover, see "Precautionary Measures" To remove a Rambus in-line memory module (RIMM), perform the following steps. CAUTION: To avoid the possibility of electric shock, turn off the computer and any peripherals, disconnect them from their electrical outlets, and then wait at least 5 seconds before you remove the computer cover.

  • Page 19: Microprocessor/Heat Sink Assembly

    8. When the System Memory total is correct, press <Esc> to exit System Setup. 9. Run the Dell Diagnostics to verify that the RIMMs are operating properly. Microprocessor/Heat Sink Assembly To replace a microprocessor, perform the following steps.
  • Page 20 To insert the new microprocessor/heat sink assembly into the system board connector, perform the following steps (this procedure assumes the microprocessor removal procedure was just performed). NOTE: Dell recommends that only a technically knowledgeable person perform this procedure. CAUTION: Before you remove the computer cover, see "Precautionary...

  • Page 21: Cooling Fan

    NOTE: If a setup password has been assigned by someone else, contact your network administrator for information on resetting the chassis intrusion detector. 8. Run the Dell Diagnostics to verify that the new microprocessor is operating correctly. Cooling Fan Figure 28. Cooling Fan Removal...

  • Page 22: System Board

    1 Battery 2 Socket NOTE: Before disconnecting a peripheral from the system or removing a component from the system board, verify that the standby power LED on the system board has turned off. For the location of this LED, see Figure CAUTION: There is a danger of the new battery exploding if it is incorrectly installed.
  • Page 23 7. Replace the computer cover, connect all cables, and restart the system. Run System Setup to ensure that your settings are correct and that all system board components are correctly reported. 8. Run the Dell Diagnostics. Back to Contents Page...
  • Page 24 AGP Card Brace System Board Overview This section provides procedures for removing and replacing the components, assemblies, and subassemblies in the Dell Precision WorkStation 420 mini tower chassis system. Unless otherwise noted, each procedure assumes that the following conditions exist: You have performed the steps in "Precautionary...
  • Page 25 damage to the system board. 4. Wear a wrist grounding strap, and clip it to an unpainted metal surface, such as the padlock loop on the back of the chassis. If a wrist grounding strap is not available, touch any unpainted metal surface on the back of the computer or on the computer chassis, such as the power supply, to discharge any static charge from your body before touching anything inside the computer.  While you work, ...
  • Page 26 1 Release button 4. Lift the bottom of the cover, allowing it to pivot up toward you. 5. Disengage the tabs that secure the cover to the top of the chassis, and lift the cover away. Figure 3. Computer Cover Replacement 1 Hook (3) 2 Recessed slot (3) To replace the computer cover, perform the following steps:...

  • Page 27: Front Panel

    Interior Service Label Figure 4 shows the location of the interior service label on the inside of the system cover. This label shows the location of components within the chassis and locations of system board components and connectors. It also contains an important notice that provides instructions you need to follow to help prevent damage to your system board while you troubleshoot and service the computer system.
  • Page 28 1 Tab release 2 Retaining hooks (2) To remove the front panel, perform the following steps: 1. While pressing the tab release marked with the icon, tilt the panel away from the chassis. 2. Disengage the two retaining hooks at the bottom of the panel. 3.
  • Page 29 Drives CAUTION: Before you remove the computer cover, see "Precautionary Measures." NOTE: In all of the following procedures, left and right refer to your left and right as you face the front of the computer. Figure 8. Drive Locations 1 3.5-inch diskette drive 2 5.25-inch drive bays (3) ...
  • Page 30 Figure 10. 3.5-Inch Diskette Drive Bracket 1 3.5-inch diskette drive 2 Retaining tabs (2) 3 Bracket 4 Screw 5.25-Inch Diskette, LS-120 SuperDisk, Tape, or CD-ROM Drive Removal To remove a diskette, LS-120 SuperDisk, tape, or CD-ROM drive, perform the following steps: Remove the computer cover.
  • Page 31 1 Metal tab 2 Drive bracket 3 Screws (4) 5.25-Inch Diskette, Tape, or CD-ROM Drive Replacement To install a replacement 5.25-inch diskette, tape, or CD-ROM drive, perform the following steps. CAUTION: Before you remove the computer cover, see Precautionary Measures. 1.
  • Page 32 For a diskette drive, update Diskette Drive A or Diskette Drive B to reflect the size and capacity of your new diskette drive. For EIDE CD-ROM and tape drives, set the appropriate Secondary Drive 0 or Secondary Drive 1 to Auto. 14. Verify that your system works correctly by running the Dell Diagnostics (see the online System User's Guide for more information).
  • Page 33 NOTE: Tape drives sold by Dell come with their own operating software and documentation. After you install a tape drive, refer to the documentation that came with the drive for instructions on installing and using the tape drive software. Hard-Disk Drive Removal CAUTION: Before you remove the computer cover, see "Precautionary...
  • Page 34 1 Drive bracket 2 Drive 3 Screws (4) 6. Reinstall the hard-disk drive bracket in the chassis (see Figure 17). Insert the bracket into the chassis by sliding it in until the tabs snap into place. Rotate the drive door up and toward the chassis until it snaps securely into place.
  • Page 35 See the documentation for your operating system for instructions. 14. Test the hard-disk drive by running the Dell Diagnostics (see the online System User's Guide for more information). 15. If the drive you just installed is the primary drive, install your operating system on the hard-disk drive.
  • Page 36 4. Replace the screw that secures the AGP card brace to the chassis (see Figure 19). Expansion Cards The Dell Precision 420 systems provide five 32-bit Peripheral Component Interconnect (PCI) expansion card slots. Slot 5 is shared with the RAID port function.
  • Page 37 Figure 21 shows the AGP card extension that occludes PCI slots 1 and 2. The following is a list of valid expansion-card combinations: One AGP card and five PCI cards One AGP card, four PCI cards, and one RAID card One AGP Pro50 card and four PCI cards One AGP Pro50 card, three PCI cards, and one RAID card One AGP Pro110 card and three PCI cards...
  • Page 38 Figure 22. Installing an Expansion Card 1 Expansion card 2 Expansion-card connector 3 Card edge connector 5. When the card is firmly seated in the connector, secure the card's mounting bracket to the chassis with the screw you removed in step 5 the removal procedure.
  • Page 39 1 Fan power cable 2 Fan 3 Plastic locking tabs (2) To remove an expansion-card guide cooling fan, perform the following steps. CAUTION: Before you remove the computer cover, see "Precautionary Measures." 1. Remove the computer cover according to the instructions in "Computer Cover."...
  • Page 40 1 Chassis intrusion cable connector 2 Control panel chassis intrusion connector 3 Enlarged hole for cable 4 Switch slot 5 Chassis intrusion switch CAUTION: Before you remove the computer cover, see "Precautionary Measures." To remove the chassis intrusion switch and install a replacement, perform the following steps: Disconnect the chassis intrusion switch cable from the control panel (see Figure 26).
  • Page 41 1 Power supply 2 Release latch 3 AC power receptacle 4 AC power cable 4. Lift the release latch and slide the power supply about 25 mm (1 inch) toward the front of the system. 5. Continue to apply pressure on the release latch while pulling the power supply towards the front of the computer and rotating the power supply out of the chassis.
  • Page 42 1 CD-ROM drive audio connector 2 Main power 1 connector (desktop chassis) 3 Diskette connector 4 Main power 2 connector (desktop chassis) 5 Battery 6 RIMM (memory) sockets 7 SCSI narrow connector 8 Secondary EIDE connector 9 Suspend-To-RAM LED 10 Jumper block (see "System Board Jumpers") 11 System board screw...
  • Page 43 33 Microphone connector 34 Mouse/keyboard (stacked) 35 System fan power connector 36 Serial port 1/ serial port 2 (stacked) 37 Parallel port/external SCSI port (stacked) System Board Jumpers Figure 29 shows the location of the jumpers on the system board. Table 1 lists the system board jumpers and their settings.
  • Page 44 FAN_SYS Microprocessor fan connector HD_LED Hard-disk drive LED connector EIDE interface connector IDEn Keyboard connector LINE_IN External microphone connector LINE_OUT External speaker connector MOUSE Mouse connector PANEL Control panel connector PARALLEL Parallel port connector PCI expansion-card connector PCIn POWER_1 Main power input connector POWER_2 3.3-V power input connector RIMM socket...
  • Page 45 8. When the System Memory total is correct, press <Esc> to exit System Setup. 9. Run the Dell Diagnostics to verify that the RIMMs are operating properly. Microprocessor/Heat Sink Assembly To replace a microprocessor, perform the following steps.
  • Page 46 NOTE: Before disconnecting a peripheral from the system or removing a component from the system board, verify that the standby power LED on the system board has turned off. For the location of this LED, see Figure Remove the computer cover.

  • Page 47: Microprocessor Cooling Fan

    NOTE: If a setup password has been assigned by someone else, contact your network administrator for information on resetting the chassis intrusion detector. 11. Run the Dell Diagnostics to verify that the new microprocessor is operating correctly. Microprocessor Cooling Fan Figure 34.
  • Page 48 Battery Figure 35. Battery Removal 1 Battery 2 Socket   CAUTION: There is a danger of the new battery exploding if it is incorrectly installed. Replace the battery only with the same or equivalent type recommended by the manufacturer. Discard used batteries according to the manufacturer’s instructions. CAUTION: Before you remove the computer cover, see "Precautionary Measures."...
  • Page 49 7. Replace the computer cover, connect cables, and turn on the power. Run the System Setup program to ensure that your settings are correct and all system board components are correctly reported. 8. Run the Dell Diagnostics. Back to Contents Page...

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