Dell Latitude 9420 Service Manual
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Dell Latitude 9420 Service Manual

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Latitude 9420
Service Manual
Regulatory Model: P141G/P142G
Regulatory Type: P141G001/P142G001
August 2021
Rev. A01

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  • Page 1 Latitude 9420 Service Manual Regulatory Model: P141G/P142G Regulatory Type: P141G001/P142G001 August 2021 Rev. A01...
  • Page 2 A WARNING indicates a potential for property damage, personal injury, or death. © 2021 Dell Inc. or its subsidiaries. All rights reserved. Dell, EMC, and other trademarks are trademarks of Dell Inc. or its subsidiaries. Other trademarks may be trademarks of their respective owners.

  • Page 3: Table Of Contents

    Contents Chapter 1: Working inside your computer..................6 Before working inside your computer..........................6 Safety precautions................................6 Entering Service Mode............................... 7 Exiting Service Mode................................7 Electrostatic discharge—ESD protection........................7 ESD field service kit ................................8 After working inside your computer..........................9 Chapter 2: Removing and installing components................10 Recommended tools................................10 Screw list....................................
  • Page 4 Deleting or changing an existing system setup password................. 72 Clearing BIOS (System Setup) and System passwords...................73 Chapter 5: Troubleshooting......................74 Handling swollen Lithium-ion batteries........................74 Dell SupportAssist Pre-boot System Performance Check diagnostics..............75 Running the SupportAssist Pre-Boot System Performance Check..............75 Built-in self-test (BIST)..............................75 M-BIST................................... 75...
  • Page 5 LCD Built-in Self Test (BIST)........................... 76 System diagnostic lights..............................77 Recovering the operating system..........................78 Backup media and recovery options..........................78 WiFi power cycle................................78 Drain residual flea power (perform hard reset)......................79 Chapter 6: Getting help and contacting Dell................80 Contents...

  • Page 6: Chapter 1: Working Inside Your Computer

    Standby power Dell products with standby power must be unplugged before you open the case. Systems that incorporate standby power are essentially powered while turned off. The internal power enables the system to be remotely turned on (wake on LAN) and suspended into a sleep mode and has other advanced power management features.

  • Page 7: Entering Service Mode

    1. Shut down your computer and disconnect the AC adapter. 2. Hold <B> key on the keyboard and press the power button for 3 seconds or until the Dell logo appears on the screen. 3. Press any key to continue.

  • Page 8: Esd Field Service Kit

    It is recommended that all field service technicians use the traditional wired ESD grounding wrist strap and protective anti-static mat at all times when servicing Dell products. In addition, it is critical that technicians keep sensitive parts separate from all insulator parts while performing service and that they use anti-static bags for transporting sensitive components.

  • Page 9: After Working Inside Your Computer

    After working inside your computer About this task NOTE: Leaving stray or loose screws inside your computer may severely damage your computer. Steps 1. Replace all screws and ensure that no stray screws remain inside your computer. 2. Connect any external devices, peripherals, or cables you removed before working on your computer. 3.

  • Page 10: Chapter 2: Removing And Installing Components

    Removing and installing components NOTE: The images in this document may differ from your computer depending on the configuration you ordered. Topics: • Recommended tools • Screw list • Major components of your computer • Secure Digital (SD) Card • SIM card tray •...

  • Page 11: Screw List

    Screw list NOTE: When removing screws from a component, it is recommended to note the screw type, the quantity of screws, and then place them in a screw storage box. This is to ensure that the correct number of screws and correct screw type is restored when the component is replaced.
  • Page 12 Table 1. Screw list (continued) Component Screw type Quantity Image Battery M1.6x3 M2x4 Left speaker M1.6x1.8 Right speaker M1.6x1.8 WLAN antenna module M1.6x1.8 M1.6x3 I/O daughter board M2x4 Power button with fingerprint M1.6x2.5 reader assembly System board M1.6x2.5 M2x4 Captive screw USH daughter board M1.2x2.5 WWAN main antenna module...

  • Page 13: Major Components Of Your Computer

    Major components of your computer 1. Base cover 2. Battery 3. Solid-state drive shielding cover 4. Wireless Wide Area Network (WWAN) shielding cover 5. Solid-state drive 6. Wireless Wide Area Network (WWAN) card 7. System board 8. Wireless Local Area Network (WLAN) Antenna module 9.

  • Page 14: Secure Digital (Sd) Card

    Secure Digital (SD) Card Removing the SD card Prerequisites Follow the procedure in before working inside your computer. About this task The following image provides a visual representation of the SD card removal procedure. Steps 1. Push the SD card to eject it from the slot. 2.

  • Page 15: Sim Card Tray

    Steps Insert the SD card into its slot until it click into place. Next steps 1. Follow the procedure in After working on your computer. SIM card tray Removing the SIM card tray Prerequisites Follow the procedure in before working inside your computer.

  • Page 16: Installing The Sim Card Tray

    Steps 1. Insert the SIM card removal pin into the release hole to release the SIM card tray. 2. Push the pin to disengage the lock, and eject the SIM card tray. 3. Slide the SIM card tray out of the slot on the system. 4.

  • Page 17: Base Cover

    Steps 1. Insert the SIM card removal pin into the release hole to remove the SIM card tray. 2. Push the pin to disengage the lock, and eject the SIM card tray. 3. Slide the SIM card tray out of the slot on the system. 4.
  • Page 18 About this task Removing and installing components...

  • Page 19: Installing The Base Cover

    Steps 1. Loosen the eight captive screws that secure the base cover to the system. 2. Using a plastic scribe, pry open the base cover starting from the recesses that are located in the U-shaped indents near the hinges at the top edge of the base cover. NOTE: Do not lift the base cover from the top side immediately after prying it from the recesses, as this will cause damage to the base cover.

  • Page 20: Solid-State Drive

    Steps 1. Align and place the base cover on the palm-rest assembly, and snap the base cover into place. 2. Tighten the eight captive screws to secure the base cover to the system. Next steps 1. Install the SIM card tray.

  • Page 21: Installing The Solid-State Drive

    About this task The following images indicate the location of the solid-state drive and provide a visual representation of the removal procedure. Steps 1. Using a plastic scribe pry open the solid-state drive shielding cover from the recess at the bottom edge of the solid-state drive shielding cover.

  • Page 22: Wireless Wide Area Network (Wwan) Card

    Steps 1. Align the notch on the solid-state drive with the tab on the M.2 card connector. 2. Slide the solid-state drive into the M.2 card connector on the system board. 3. Replace the single (M1.6x2.5) screw that secures the solid-state drive to the system board. 4.
  • Page 23 3. Remove the SIM card tray. 4. Enter service mode. 5. Remove the base cover. About this task The following images indicate the location of the WWAN card and provide a visual representation of the removal procedure. Steps 1. Loosen the single captive screw securing the WWAN-card bracket to the system board. 2.

  • Page 24: Installing The Wwan Card

    Installing the WWAN card Prerequisites If you are replacing a component, remove the existing component before performing the installation procedure. About this task The following image indicates the location of the WWAN card and provides a visual representation of the installation procedure. Steps 1.

  • Page 25: System Fan

    5. Align and place the WWAN-card bracket on the system board and WWAN card, and tighten the single captive screw. NOTE: For instructions on how to find your computer's IMEI (International Mobile Station Equipment Identity) number, see the knowledge base article 000143678 at www.dell.com/support. Next steps 1. Install the base cover.

  • Page 26: Installing The System Fan

    Steps 1. Peel the single piece of tape securing the system fan cable to the system board. 2. Disconnect the system fan cable from the connector on the system board. 3. Remove the two (M1.6x2.5) screws that secure the system fan to the palm-rest assembly. 4.

  • Page 27: Heat Sink

    Steps 1. Align and place the system fan onto the palm-rest assembly. 2. Replace the two (M1.6x2.5) screws that secure the system fan to the palm-rest assembly. 3. Connect the system fan cable to the connector on the system board. 4.

  • Page 28: Installing The Heat Sink

    Steps 1. Peel the two pieces of tape securing the gray WWAN antenna cable from the bottom side of the CPU shielding cover. 2. Peel the piece of conductive tape and the tape securing the system fan cable from the left side of the CPU shielding cover. 3.
  • Page 29 Steps 1. Align the screw holes on the heat sink with the screw holes on the system board. 2. Tighten the three captive screws that secure the heat sink to the system board. 3. Align and place the CPU shielding cover correctly into the small notches, and press to fit it firmly. 4.

  • Page 30: Display Assembly

    Display assembly Removing the display assembly Prerequisites 1. Follow the procedure in before working inside your computer. 2. Remove the card. 3. Remove the SIM card tray. 4. Enter service mode. 5. Remove the base cover. About this task The following images indicate the location of the display assembly and provide a visual representation of the removal procedure. NOTE: The display assembly removal procedure is the same for both laptop and 2-in-1 chassis.
  • Page 31 Steps 1. Disconnect the display cable from the connector on the system board. CAUTION: The connector for the display cable features a latch that locks it in place on the system board. Flip open the display cable latch from the two tabs on the top side of the latch. After flipping open the latch, hold the left and right sides of the cable's connector head and gently disconnect the display cable from the system board in a direct upward motion to prevent damage to the connector's pins.

  • Page 32: Installing The Display Assembly

    5. Lift the display assembly off the computer. Installing the display assembly Prerequisites If you are replacing a component, remove the existing component before performing the installation procedure. NOTE: The display assembly installation procedure is the same for both laptop and 2-in-1 chassis. About this task The following image indicates the location of the display assembly and provides a visual representation of the installation procedure.

  • Page 33: Battery

    Steps 1. Align and place the palm-rest assembly under the hinges of the display assembly. 2. Replace the six (M2.5x3) screws that secure the display assembly to the system. 3. Connect the display and camera cable to the connector on the system board. Next steps 1.

  • Page 34: Removing The Battery

    ● If the battery gets stuck inside your computer as a result of swelling, do not try to release it as puncturing, bending, or crushing a lithium-ion battery can be dangerous. In such an instance, contact Dell technical support for assistance. See www.dell.com/contactdell.
  • Page 35 Steps 1. Peel off the two pieces of tape securing the gray WWAN antenna cable in place at the bottom side of CPU shielding cover and unroute the wireless antenna cables from the routing guides on the system board and the routing guides along the top side of the battery.

  • Page 36: Installing The Battery

    8. Peel off the piece of tape securing the speaker cable in place at the left side of the battery. 9. Unroute the speaker cables from the routing guides at the left and right side of the battery. 10. Remove the single (M1.6x3) screw and four (M2x4) screws that secures the battery to the plam-rest assembly. 11.

  • Page 37: Speakers

    Steps 1. Align and place the battery on the palm-rest assembly. 2. Replace the single (M1.6x3) screw and four (M2x4) screws to secure the battery to the palm-rest assembly. 3. Reconnect the battery cable to the connector on the system board. 4.

  • Page 38: Installing The Left Speaker

    Steps 1. Remove the single (M1.6x1.8) screw securing the Proximity sensor bracket to the plam-rest assembly. 2. Disconnect the Proximity sensor cable for the left speaker's WWAN antenna module from the RF board. 3. Disconnect the left speaker cable from connector on the system board, and unroute the speaker cable from the routing guides.

  • Page 39: Removing The Right Speaker

    Steps 1. Align and place the left speaker in the slot on the system. 2. Replace the single (M1.6x1.8) screw that secure the left speaker to the system. 3. Route the speaker cables through the routing guide and connect the speaker cable to the connector on the system board. 4.

  • Page 40: Installing The Right Speaker

    Installing the right speaker Prerequisites If you are replacing a component, remove the existing component before performing the installation procedure. About this task The following image indicates the location of the speaker and provides a visual representation of the installation procedure. Steps 1.

  • Page 41: Installing The Wlan Antenna Module

    5. Remove the WWAN card. 6. Remove the battery. About this task The following images indicate the location of the WLAN antenna module and provide a visual representation of the removal procedure. Steps 1. Remove the single (M1.6x1.8) screw securing the Proximity sensor bracket to the plam-rest assembly and lift the Proximity sensor bracket off the system.
  • Page 42 About this task The following image indicates the location of the WLAN antenna module and provides a visual representation of the installation procedure. Steps 1. Align and place the WLAN antenna module in the slot on the system. 2. Replace the two (M1.6x3) screws that secure the WLAN antenna module to the palm-rest assembly. 3.

  • Page 43: I/O Daughter Board

    I/O daughter board Removing the I/O daughter board Prerequisites 1. Follow the procedure in before working inside your computer. 2. Enter service mode. 3. Remove the card. 4. Remove the SIM card tray. 5. Remove the base cover. 6. Remove the heat sink.

  • Page 44: Installing The I/O Daughter Board

    5. Disconnect the I/O daughter board FPC cable from the I/O daughter board. Installing the I/O daughter board Prerequisites If you are replacing a component, remove the existing component before performing the installation procedure. About this task The following image indicates the location of the I/O daughter board and provides a visual representation of the installation procedure.

  • Page 45: Power Button With Fingerprint Reader Assembly

    4. Install the SIM card tray. 5. Install the card. 6. Exit service mode. 7. Follow the procedure in After working on your computer. Power button with fingerprint reader assembly Removing the power button with fingerprint reader assembly Prerequisites NOTE: For system shipped with power button with fingerprint reader assembly only.

  • Page 46: Installing The Power Button With Fingerprint Reader Assembly

    Installing the power button with fingerprint reader assembly Prerequisites If you are replacing a component, remove the existing component before performing the installation procedure. About this task The following image indicate the location of the power button and provide a visual representation of the installation procedure. Steps 1.
  • Page 47 2. Remove the card. 3. Remove the SIM card tray. 4. Remove the base cover. 5. Remove the solid-state drive 6. Remove the WWAN card. 7. Remove the heat sink. 8. Remove the battery. About this task 1. I/O daughter board cable connector 2.
  • Page 48 NOTE: Do not remove the system board together with the heat-sink, as this may damage the I/O daughter board, I/O daughter board FPC, and system board. The system features an I/O daughter board FPC which is connected to the system board underneath the heat-sink, as a result, the heat-sink must be removed first in order to disconnect the I/O daughter board FPC from the system board and then remove the system board.

  • Page 49: Installing The System Board

    NOTE: Flip open the display cable latch from the two tabs on the top side of the latch. Hold the left and right sides of the cable's connector head and gently disconnect the display cable in a direct upward motion to prevent damage to the connector.
  • Page 50 Steps 1. Align and place the system board on the palm-rest assembly. 2. Replace the four (M1.6x2.5) screws that secure the system board to the palm-rest assembly. 3. Replace the three (M2x4) screws that secures the USB Type-C bracket to the system board. 4.

  • Page 51: Ush Daughter Board

    13. Connect the display cable and camera cable to the connector on the system board. 14. Connect the display cable, and camera cable to the system board. 15. Connect the power button with fingerprint reader FPC cable to the connector on the system board (For the systems shipped with power button with fingerprint reader assembly).

  • Page 52: Installing The Ush Daughter Board

    Steps 1. Gently disconnect the power button with fingerprint reader FPC cable from the connector on the USH daughter board. 2. Peel off the USH daughter board FPC cable from the keyboard. 3. Remove the two (M1.2x2.5) screws securing the USH daughter board to the palm-rest assembly. 4.

  • Page 53: Wireless Wide Area Network (Wwan) Antenna Module

    Steps 1. Connect the USH daughter board FPC cable from USH daughter board. 2. Place the USH daughter board with the FPC cable in the slot on the system. 3. Replace the two (M1.2x2.5) screws securing the USH daughter board to the palm-rest assembly 4.

  • Page 54: Installing The Wwan Main Antenna Module

    6. Remove the heat sink. 7. Remove the display assembly. 8. Remove the battery. 9. Remove the I/O daughter board. 10. Remove the system board. 11. Remove the USH daughter board. About this task The following images indicate the location of the WWAN main antenna module and provide a visual representation of the removal procedure.

  • Page 55: Palm-Rest Assembly

    Steps 1. Align and place the WWAN main antenna module in the slot on the system. 2. Replace the four (M1.6x3) screws that secure the WWAN main antenna module to the palm-rest assembly. Next steps 1. Install the system board 2.

  • Page 56: Installing The Palm-Rest Assembly

    10. Remove the left speaker. 11. Remove the right speaker. 12. Remove the WLAN antenna module. 13. Remove the I/O daughter board. 14. Remove the power button with fingerprint reader assembly (for systems shipped with a fingerprint reader). 15. Remove the system board.
  • Page 57 Steps Place the palm-rest assembly on a flat surface. Next steps 1. Install the WWAN main antenna module. 2. Install the USH daughter board. 3. Install the system board 4. Install the power button with fingerprint reader (for systems shipped with a fingerprint reader). 5.

  • Page 58: Chapter 3: Software

    Downloading the drivers Steps 1. Turn on your computer. 2. Go to www.dell.com/support. 3. Enter the Service Tag of your computer, and then click Submit. NOTE: If you do not have the Service Tag, use the auto-detect feature or manually browse for your computer model.

  • Page 59: Chapter 4: Bios Setup

    BIOS setup CAUTION: Unless you are an expert computer user, do not change the settings in the BIOS Setup program. Certain changes can make your computer work incorrectly. NOTE: Depending on the computer and its installed devices, the items listed in this section may or may not be displayed. NOTE: Before you change BIOS Setup program, it is recommended that you write down the BIOS Setup program screen information for future reference.

  • Page 60: One Time Boot Menu

    Table 2. Navigation keys Keys Navigation Up arrow Moves to the previous field. Down arrow Moves to the next field. Enter Selects a value in the selected field (if applicable) or follow the link in the field. Spacebar Expands or collapses a drop-down list, if applicable. Moves to the next focus area.
  • Page 61 Table 3. System setup options—System information menu (continued) Overview Battery Level Displays the battery level of the computer. Battery State Displays the battery state of the computer. Health Displays the battery health of the computer. AC Adapter Displays whether the AC adapter is connected or not. Processor Information Processor Type Displays the processor type.
  • Page 62 Table 4. System setup options—Boot Configuration menu (continued) Boot Configuration Boot mode Displays the boot mode. Boot Sequence Displays the boot sequence. Secure Digital (SD) Card Boot Enable or disable the SD card read-only boot. By default, the Secure Digital (SD) Card Boot option is not enabled. Secure Boot Enable Secure Boot Enable or disable the secure boot feature.
  • Page 63 By default, the Video/Power only on Type-C Ports option is disabled. Type-C Dock Override Enables to use connected Type-C Dell Dock to provide data stream with external USB ports disabled. When Type-C Dock override is enabled, the Video/Audio/Lan submenu is activated.
  • Page 64 Table 6. System setup options—Storage menu (continued) Storage By default, the Secure Digital (SD) Card Read-Only Mode option is not enabled. Table 7. System setup options—Display menu Display Display Brightness Brightness on battery power Enable to set screen brightness when the computer is running on battery power.
  • Page 65 By default, the Optimized option is enabled. USB Wake Support Wake on Dell USB-C Dock When enabled, connecting a Dell USB-C Dock will wake the computer from standby. By default, the Wake on Dell USB-C Dock option is enabled. Block Sleep Enables to block entering sleep (S3) mode in the operating system.
  • Page 66 Table 10. System setup options—Security menu (continued) Security TPM 2.0 Security On Enable or disable TPM 2.0 security options. By default, the TPM 2.0 Security On option is enabled. Attestation Enable Enables to control whether the Trusted Platform Module (TPM) Endorsement Hierarchy is available to the operating system.
  • Page 67 Allow Non-Admin PSID Revert Enable Allow Non-Admin PSID Revert Controls access to the Physical Security ID (PSID) revert of NVMe hard-drives from the Dell Security Manager prompt. By default, the option is disabled. Table 12. System setup options—Update, Recovery menu...
  • Page 68 By default, the option is enabled. Dell Auto OS Recovery Threshold Controls the automatic boot flow for SupportAssist System Resolution Console and for Dell OS Recovery Tool. By default, the threshold value is set to 2. Table 13. System setup options—System Management menu...
  • Page 69 Table 15. System setup options—Pre-boot Behavior menu Pre-boot Behavior Adapter Warnings Enable Adapter Warnings Enable or disable the warning messages during boot when the adapters with less power capacity are detected. By default, the option is enabled. Warning and Errors Enable or disable the action to be done when a warning or error is encountered.

  • Page 70: Updating The Bios

    Steps 1. Go to www.dell.com/support. 2. Click Product support. In the Search support box, enter the Service Tag of your computer, and then click Search. NOTE: If you do not have the Service Tag, use the SupportAssist feature to automatically identify your computer. You can also use the product ID or manually browse for your computer model.

  • Page 71: Updating The Bios From The F12 One-Time Boot Menu

    One-Time boot menu on the computer. Most of the Dell computers built after 2012 have this capability, and you can confirm by booting your computer to the F12 One-Time Boot Menu to see if BIOS FLASH UPDATE is listed as a boot option for your computer. If the option is listed, then the BIOS supports this BIOS update option.

  • Page 72: System And Setup Password

    5. Select the file and double-click the flash target file, and then click Submit. 6. Click Update BIOS. The computer restarts to flash the BIOS. 7. The computer will restart after the BIOS update is completed. System and setup password Table 18.

  • Page 73: Clearing Bios (System Setup) And System Passwords

    Clearing BIOS (System Setup) and System passwords About this task To clear the system or BIOS passwords, contact Dell technical support as described at www.dell.com/contactdell. NOTE: For information on how to reset Windows or application passwords, refer to the documentation accompanying Windows or your application.

  • Page 74: Chapter 5: Troubleshooting

    ● Using a non-Dell or incompatible battery may increase the risk of fire or explosion. Replace the battery only with a compatible battery purchased from Dell that is designed to work with your Dell computer. Do not use a battery from other computers with your computer.

  • Page 75: Dell Supportassist Pre-Boot System Performance Check Diagnostics

    Check diagnostics About this task SupportAssist diagnostics (also known as system diagnostics) performs a complete check of your hardware. The Dell SupportAssist Pre-boot System Performance Check diagnostics is embedded with the BIOS and is launched by the BIOS internally. The embedded system diagnostics provides a set of options for particular devices or device groups allowing you to: ●...

  • Page 76: Lcd Power Rail Test (L-Bist)

    LCD Built-in Self Test (BIST) Dell laptops have a built-in diagnostic tool that helps you determine if the screen abnormality you are experiencing is an inherent problem with the LCD (screen) of the Dell laptop or with the video card (GPU) and PC settings.

  • Page 77: System Diagnostic Lights

    System diagnostic lights Battery-status light Indicates the power and battery-charge status. Solid white — Power adapter is connected and the battery has more than 5 percent charge. Amber — Computer is running on battery and the battery has less than 5 percent charge. ●...

  • Page 78: Recovering The Operating System

    It enables you to diagnose hardware issues, repair your computer, back up your files, or restore your computer to its factory state. You can also download it from the Dell Support website to troubleshoot and fix your computer when it fails to boot into their primary operating system due to software or hardware failures.

  • Page 79: Drain Residual Flea Power (Perform Hard Reset)

    5. Press and hold the power button for 20 seconds to drain the flea power. 6. Install the battery. 7. Install the base cover. 8. Connect the power adapter to your computer. 9. Turn on your computer. NOTE: For more information about performing a hard reset, see the knowledge base article 000130881 www.dell.com/support. Troubleshooting...

  • Page 80: Chapter 6: Getting Help And Contacting Dell

    Getting help and contacting Dell Self-help resources You can get information and help on Dell products and services using these self-help resources: Table 20. Self-help resources Self-help resources Resource location Information about Dell products and services www.dell.com Tips Contact Support In Windows search, type Contact Support, and press Enter.

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