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.
Back to Contents Page Desktop Chassis — Removing and Replacing Parts: Dell Precision™ WorkStation 420 Systems Service Manual Overview Control Panel Recommended Tools Chassis Intrusion Switch Precautionary Measures Drives Restarting the System Power Supply Computer Cover System Board Components Interior Service Label RIMMs Internal View Microprocessor/Heat Sink Assembly Front-Panel Inserts Cooling Fan Expansion Cards Battery Expansion-Card Guide System Board Overview This section provide
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.
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. Check to see that no tools or extra parts (including screws) are left inside the computer's chassis. 3.
1 Externally accessible drive bays 2 Hard-disk drive bracket 3 System board 4 Expansion card slots 5 Padlock ring 6 I/O panel connectors 7 Security cable slot 8 AC power receptacle 9 Power supply 10 Drive data cable Front-Panel Inserts Figure 5. 5.25-Inch Front-Panel Insert Removal 1 Front-panel insert 2 Ring tabs (2) 3 Posts (2) To remove a 5.25-inch front-panel insert, perform the following steps: 1. Hold the inverted top cover with the front facing you. 2.
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: l One AGP card and five PCI cards l One AGP card, four PCI cards, and one RAID card l One AGP Pro50 card and four PCI cards l One AGP Pro50 card, three PCI cards, and one RAID card Expansion Card Removal To remove an expansion card, perform the following steps.
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: 1. Remove the hard-disk drive bracket. 2. Face the computer from the front.
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. Disconnect the thermal sensor cable connector from the control panel. 5. Disconnect the speaker cable connector from the control panel. 6. Remove the control panel and cable from the chassis.
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 Measures" To remove the 3.5-inch diskette drive assembly, perform the following steps: 1. Rotate the system power supply up and out of the system (see Figure 20). 2.
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. Then replace the screw that holds the diskette drive to the bracket. To replace the 3.
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. CAUTION: Before you remove the computer cover, see "Precautionary Measures." 1. Remove the computer cover. 2. Disconnect the DC power cable and data cable from the drive. 3.
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. CAUTION: Before you remove the computer cover, see "Precautionary Measures." 1.
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. Connect one of the device connectors on the EIDE cable to the 40-pin interface connector on the back of the hard-disk drive. NOTICE: You must match the colored strip on the EIDE cable with pin 1 on the drive's interface connector to avoid possible damage to your system.
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. Power Supply To access some components on the system board, you may have to rotate the system power supply out of the way. To rotate the power supply, perform the following steps.
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.
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 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 23 shows the loca
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.
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. CAUTION: The RIMMs can get extremely hot during system operation.
NOTE: After you remove and replace the cover, the chassis intrusion detector causes the following message to appear on the screen at the next system start-up: ALERT! Cover was previously removed. The system detects that the new memory does not match the existing system configuration information and generates the following message: The amount of system memory has changed. Strike the F1 key to continue, F2 to run the setup utility 5. Press to enter System Setup, and check the value for System Memory.
1 Airflow shroud 2 Thumbscrews (2) 3 Processor/heat sink assembly 4 Guide bracket 5 Second processor Figure 27. Microprocessor Replacement 1 Airflow shroud 2 Thumbscrews (2) 3 Processor/heat sink assembly 4 Guide bracket 5 Second processor 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).
4. Rotate the power supply back into position, making sure that the securing tab snaps into place. 5. Replace the computer cover, and reconnect your computer and peripherals to their power sources and turn them on. NOTE: After you remove and replace the cover, the chassis intrusion detector will cause the following message to be displayed at the next system start-up: ALERT! Cover was previously removed. 6.
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 22. 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.
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 22. CAUTION: The microprocessors and RIMMs can get extremely hot during system operation. To avoid dangerous burns, be sure that the microprocessors and RIMMs have had sufficient time to cool before you touch them. 1. Remove the computer cover. 2.
Back to Contents Page Mini Tower Chassis — Removing and Replacing Parts: Dell Precision™ WorkStation 420 Systems Service Manual Overview Expansion Cards Recommended Tools Expansion-Card Guide and Fan Precautionary Measures Control Panel Restarting the System Chassis Intrusion Switch Computer Cover Power Supply Interior Service Label System Board Components Internal View RIMMs Front Panel Microprocessor/Heat Sink Assembly Front-Panel Inserts Microprocessor Cooling Fan Drives Battery AGP
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.
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: 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.
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. Figure 4.
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. Carefully pull the panel away from the chassis. To replace the front panel, perform the following steps: 1. Fit the two retaining hooks on the panel into their corresponding slots at the bottom of the mini tower chassis (see Figure 6). 2.
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) 3 Hard-disk drive Diskette Drive Removal To remove the 3.5-inch diskette drive assembly, perform the following steps: 1. Disconnect the DC power/interface cables from the back of the diskette drive.
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: 1. Remove the computer cover. 2. Disconnect the DC power cable and interface cable from the back of the drive. 3. Squeeze the metal tabs that extend from each side of the drive bracket toward each other. 4.
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. Unpack the replacement drive and prepare it for installation. NOTICE: Ground yourself by either wearing a wrist grounding strap or by touching an unpainted metal surface on the computer chassis.
1 Drive 7. Connect a DC power cable to the power input connector on the back of the drive (see Figure 14). 8. Connect the appropriate interface cable to the interface connector on the back of the drive (see Figure 14). If your system came with an EIDE CD-ROM or tape drive, use the spare connector on the existing interface cable. Otherwise, use the EIDE interface cable provided in the drive kit.
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 Measures." 1. Remove the computer cover. 2. Remove the front panel as instructed in "Front Panel." 3.
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. Be sure to fold down the drive door handle (see Figure 17) so that the front panel can be replaced on the chassis. Figure 17. Inserting the Drive Bracket 1 Chassis drive cage 2 Drive bracket 3 Tabs 7.
1 EIDE cable 2 Power input connector 3 Interface connector 4 DC power cable 9. If it is not already connected, connect the other end of the EIDE cable to the IDE1 connector on the system board. NOTICE: You must match the colored strip on the EIDE cable with pin 1 on the IDE1 connector to avoid possible damage to your system. 10. Replace the computer cover and the front panel. Then reconnect your computer and peripherals to their power sources, and turn them on. 11.
1 Card guide (front of chassis) 2 AGP card brace 3 Card brace spring 4 Screw 5 Plastic card guide 6 Slot 7 Tab on AGP card brace 3. Slide the card brace forward until it disengages from the slot in the card guide, then rotate the brace up and lift it away from the chassis. To replace the card brace, perform the following steps: 1. Insert the tab on the end of the card brace into the slot above the card guide at the front of the chassis (see Figure 19). 2.
Figure 21 shows the AGP card extension that occludes PCI slots 1 and 2. The following is a list of valid expansion-card combinations: l One AGP card and five PCI cards l One AGP card, four PCI cards, and one RAID card l One AGP Pro50 card and four PCI cards l One AGP Pro50 card, three PCI cards, and one RAID card One AGP Pro110 card and three PCI cards l One AGP Pro110 card, two PCI cards, and one RAID card Expansion-Card Removal To remove an expansion card, perform the following steps.
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 of the removal procedure. 6. Connect any cables that should be attached to the card. Expansion-Card Guide and Fan Figure 23. Expansion-Card Guide and Fan Removal 1 Tab 2 Expansion-card guide To remove the expansion-card guide and fan, perform the following steps.
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." 2. Rotate the power supply. 3. Remove the expansion-card guide and fan. 4. Squeeze the tabs on the end of the fan bracket and slide the fan off of the expansion-card guide (see Figure 24). Control Panel Figure 25.
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: 1. Disconnect the chassis intrusion switch cable from the control panel (see Figure 26). Note the routing of the chassis intrusion cable as you remove the cable from the chassis.
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. See the instruction label on the side of the power supply for additional information.
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 12 LVD SCSI connector 13 Primary EIDE connector 14 Standby power LED 15 Control panel connector 16 MT power 2 connector (mini tower chassis) 17 MT power 1 connector (mini tower chassis) 18 Modem (TAPI)
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. Figure 29. System Board Jumpers Jumpers are small blocks on a circuit board with two or more pins emerging from them. Plastic plugs containing a wire fit down over the pins.
FAN_SYS Microprocessor fan connector HD_LED Hard-disk drive LED connector IDEn EIDE interface connector KYB Keyboard connector LINE_IN External microphone connector LINE_OUT External speaker connector MOUSE Mouse connector PANEL Control panel connector PARALLEL Parallel port connector PCIn PCI expansion-card connector POWER_1 Main power input connector POWER_2 3.
2. If necessary, remove any RIMMs that occupy sockets in which you plan to install the RIMMs. NOTES: If you are not installing a replacement RIMM at this time, you MUST remove the remaining RIMM in the pair and install a pair of continuity modules (CRIMM). When operating with a single pair of RIMMs, they MUST occupy sockets RIMMB-1 and RIMMA-2, with CRIMMs installed in RIMMB-3 and RIMMA-4. 3. Install the RIMMs. a. Locate the plastic securing clips at each end of the socket (see Figure 31). b.
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 28. 1. Remove the computer cover. 2. Rotate the power supply. 3. Remove the existing microprocessor from its connector. Squeeze in on the two pairs of tabs on the airflow shroud and lift it away. Press outward on the guide bracket tabs to release them from the processor/heat sink assembly.
Press the processor firmly into its connector until it is fully seated. You must use up to 25 lb of force to fully seat the processor in its connector. 5. Install the two thumbscrews. 6. Replace the airflow shroud. 7. Rotate the power supply back into position, making sure that the securing tab snaps into place. 8. Replace the computer cover, and reconnect your computer and peripherals to their power sources and turn them on.
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.
1 System board 2 Screw To remove the system board, perform the following steps. CAUTION: Before you remove the computer cover, see "Precautionary Measures." 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 28. 1. Remove the computer cover. 2. Disconnect all cables from their connectors at the back of the computer. 3.