OptiPlex 7400 Service Manual Regulatory Model: W26C Regulatory Type: W26C005/W26C006 March 2022 Rev.
Notes, cautions, and warnings NOTE: A NOTE indicates important information that helps you make better use of your product. CAUTION: A CAUTION indicates either potential damage to hardware or loss of data and tells you how to avoid the problem. WARNING: A WARNING indicates a potential for property damage, personal injury, or death. © 2022 Dell Inc. or its subsidiaries. All rights reserved. Dell, EMC, and other trademarks are trademarks of Dell Inc. or its subsidiaries.
Contents Chapter 1: Working inside your computer...................................................................................... 6 Safety instructions.............................................................................................................................................................. 6 Before working inside your computer....................................................................................................................... 6 Safety precautions....................
Removing the coin-cell battery................................................................................................................................36 Installing the coin-cell battery.................................................................................................................................. 37 Wireless card......................................................................................................................................................................
Removing the display panel.......................................................................................................................................76 Installing the display panel......................................................................................................................................... 78 Middle frame......................................................................................................................................................................
1 Working inside your computer Safety instructions Use the following safety guidelines to protect your computer from potential damage and to ensure your personal safety. Unless otherwise noted, each procedure included in this document assumes that you have read the safety information that shipped with your computer. WARNING: Before working inside your computer, read the safety information that is shipped with your computer. For more safety best practices, see the Regulatory Compliance home page at www.dell.
NOTE: If you are using a different operating system, see the documentation of your operating system for shut-down instructions. 3. Disconnect your computer and all attached devices from their electrical outlets. 4. Disconnect all attached network devices and peripherals, such as keyboard, mouse, and monitor from your computer. 5. Remove any media card and optical disc from your computer, if applicable. 6.
the damage. The weakened trace may take weeks or months to melt, and in the meantime may cause degradation of memory integrity, intermittent memory errors, etc. The more difficult type of damage to recognize and troubleshoot is the intermittent (also called latent or "walking wounded") failure. Perform the following steps to prevent ESD damage: ● Use a wired ESD wrist strap that is properly grounded. The use of wireless anti-static straps is no longer allowed; they do not provide adequate protection.
ESD protection summary 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.
2 Removing and installing components NOTE: The images in this document may differ from your computer depending on the configuration you ordered. Recommended tools The procedures in this document may require the following tools: ● Phillips screwdriver #1 ● Plastic scribe 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.
Table 1. Screw list (continued) Component Screw type Quantity Screw image Camera assembly M3x5 2 Camera door M3x5 2 Heat sink—UMA Captive screws 5 Heat sink—Discrete Captive screws 9 Power-supply unit (PSU) M3x5 1 PSU fan M3x5 2 Rear-I/O bracket M3x5 4 System board M3x5 9 Speakers M3 4+7.1xZN 6 Power-button board M3x5 1 Microphones M2x2.5 2 Side I/O-board shield M3x5 2 Side-I/O board M2.5x3.5 2 Antenna modules M2x2.
Major components of OptiPlex 7400 All-in-One The following image shows the major components of OptiPlex 7400 All-in-One. 1. 3. 5. 7. 9. 11. 13. 15. 17. 19. 21. Stand Heat sink Processor M.2 2230/2280 solid-state drive Side-I/O board Audio board Display-assembly base Camera-assembly door System board Camera assembly PSU fan 2. Bottom cover 4. System fan 6. Memory module 8. Rear-I/O bracket 10. Speakers 12. Display panel 14. Middle frame 16. Power-supply unit (PSU) 18. System-board shield 20.
Stand Removing the fixed stand Prerequisites 1. Follow the procedure in Before working inside your computer. CAUTION: When servicing the system, place it on an elevated, clean, and flat surface. Dell Technologies recommends removing the stand to avoid accidental damage to the system display during servicing. About this task The following image provides a visual representation of the fixed stand removal procedure. Steps 1. Press and slide the release button up. 2.
About this task The following image provides a visual representation of the fixed stand installation procedure. Steps Align and insert the hooks on the mounting bracket on the stand into the slots on the monitor, until you hear a click. Next steps 1. Follow the procedure in After working inside your computer. Removing the height adjustable stand Prerequisites NOTE: Follow the same procedure to remove the Height Adjustable Stand with Optical Disk Drive. 1.
Steps 1. Press and slide the release button up. 2. Hold the button in the release position, and lift the stand upward. 3. Slide the stand downward, to lift the stand off the back cover. Installing the height adjustable stand Prerequisites If you are replacing a component, remove the existing component before performing the installation procedure. NOTE: Follow the same procedure to install the Height Adjustable Stand with Optical Disk Drive.
Steps 1. Align the tabs on the stand with the slots on the back cover. 2. Slide the stand upward until it clicks into place. Next steps 1. Follow the procedure in After working inside your computer. Cable cover—optional Removing the cable cover Prerequisites 1. Follow the procedure in Before working inside your computer. CAUTION: When servicing the system, place it on an elevated, clean, and flat surface.
Steps 1. Unroute the power cable from the slots on the cable cover. 2. Remove the screw (M3x9) that secures the cable cover to the bottom cover. 3. Lift the cable cover from the bottom cover.
Installing the cable cover Prerequisites If you are replacing a component, remove the existing component before performing the installation procedure.
Steps 1. Route the power cable through the slots on the cable cover. 2. Align the screw hole on the cable cover with the screw hole on the bottom cover. 3. Replace the screw (M3x9) to secure the cable cover to the bottom cover. Next steps 1. Install the stand. 2. Follow the procedure in After working inside your computer. Back cover Removing the back cover Prerequisites 1. Follow the procedure in Before working inside your computer.
Steps 1. Press and hold the release tab on the back cover to release it from the latch on the system-board shield. 2. Slide the back cover up to release the tabs on the cover from the slots on the middle frame. 3. Lift the back cover and remove it from the system.
Installing the back cover Prerequisites If you are replacing a component, remove the existing component before performing the installation procedure. About this task The following image provides a visual representation of the back cover installation procedure.
Steps 1. Place the back cover on the middle frame and system-board shield and align the tabs on the back cover with the slots on the middle frame. 2. Slide the back cover to lock the release tab under the latch on the system-board shield. Next steps 1. Install the cable cover (optional). 2. Install the stand. 3. Follow the procedure in After working inside your computer. Memory modules Removing the memory modules Prerequisites 1. 2. 3. 4. Follow the procedure in Before working inside your computer.
Steps 1. Pry and remove the DIMM door from the system-board shield. 2. Using your fingertips, spread apart the securing clips on the memory-module slot until the memory module pops up. 3. Slide and remove the memory module from the memory-module slot. NOTE: Repeat step 2 and 3 if there are two memory modules. Installing the memory modules Prerequisites If you are replacing a component, remove the existing component before performing the installation procedure.
Steps 1. Align the notch on the memory module with the tab on the memory-module slot. 2. Slide the memory module firmly into the slot at an angle and press the memory module down until it clicks into place. NOTE: If you do not hear the click, remove the memory module and reinstall it. NOTE: Repeat step 1 and 2 if there are two memory modules. 3. Align the tabs on the DIMM door with the slots on the system-board shield and snap into place. Next steps 1. 2. 3. 4. Install the back cover.
2. Remove the stand. 3. Remove the cable cover (optional). 4. Remove the back cover. About this task The following image indicates the location of the system-board shield and provides a visual representation of the removal procedure. Steps 1. Remove the five screws (M3x5) that secure the system-board shield to the display-assembly base. 2. Lift the system-board shield off the display-assembly base.
Steps 1. Align the screw holes on the system-board shield with the screw holes on the display-assembly base. 2. Replace the five screws (M3x5) to secure the system-board shield to the display-assembly base. Next steps 1. 2. 3. 4. Install the back cover. Install the cable cover (optional). Install the stand. Follow the procedure in After working inside your computer. Solid-state drive Removing the M.2 2230 solid-state drive-slot 1 Prerequisites 1. 2. 3. 4. 5.
About this task The following image indicates the location of the slot-1 M.2 2230 solid-state drive and provides a visual representation of the removal procedure. Steps 1. Remove the screw (M2x2.5) that secures the solid-state drive to the system board. 2. Slide and remove the solid-state drive from the M.2 card slot on the system board. Installing the M.2 2230 solid-state drive-slot 1 Prerequisites CAUTION: Solid-state drives are fragile. Exercise care when handling the solid-state drive.
Steps 1. Align the notch on the solid-state drive with the tab on the M.2 card slot. 2. Slide the solid-state drive into the M.2 card slot on the system board. 3. Replace the screw (M2x2.5) to secure the solid-state drive to the system board. Next steps 1. 2. 3. 4. 5. Install the system-board shield. Install the back cover. Install the cable cover (optional). Install the stand. Follow the procedure in After working inside your computer. Removing the M.2 2280 solid-state drive-slot 1 Prerequisites 1. 2. 3.
Steps 1. Remove the screw (M2x2.5) that secures the solid-state drive to the system board. 2. Slide and remove the solid-state drive from the M.2 card slot on the system board. Installing the M.2 2280 solid-state drive-slot 1 Prerequisites CAUTION: Solid-state drives are fragile. Exercise care when handling the solid-state drive. If you are replacing a component, remove the existing component before performing the installation procedure.
Steps 1. Align the notch on the solid-state drive with the tab on the M.2 card slot. 2. Slide the solid-state drive into the M.2 card slot on the system board. 3. Replace the screw (M2x2.5) to secure the solid-state drive to the system board. Next steps 1. 2. 3. 4. 5. Install the system-board shield. Install the back cover. Install the cable cover (optional). Install the stand. Follow the procedure in After working inside your computer. Removing the M.2 2230 solid-state drive-slot 2 Prerequisites 1. 2. 3.
Steps 1. Remove the screw (M2x2.5) that secures the solid-state drive to the system board. 2. Slide and remove the solid-state drive from the M.2 card slot on the system board. Installing the M.2 2230 solid-state drive-slot 2 Prerequisites CAUTION: Solid-state drives are fragile. Exercise care when handling the solid-state drive. If you are replacing a component, remove the existing component before performing the installation procedure.
Steps 1. Align the notch on the solid-state drive with the tab on the M.2 card slot. 2. Slide the solid-state drive into the M.2 card slot on the system board. 3. Replace the screw (M2x2.5) to secure the solid-state drive to the system board. Next steps 1. 2. 3. 4. 5. Install the system-board shield. Install the back cover. Install the cable cover (optional). Install the stand. Follow the procedure in After working inside your computer. Removing the M.2 2280 solid-state drive-slot 2 Prerequisites 1. 2. 3.
Steps 1. Remove the screw (M2x2.5) that secures the solid-state drive to the system board. 2. Slide and remove the solid-state drive from the M.2 card slot on the system board. Installing the M.2 2280 solid-state drive-slot 2 Prerequisites CAUTION: Solid-state drives are fragile. Exercise care when handling the solid-state drive. If you are replacing a component, remove the existing component before performing the installation procedure.
Steps 1. Align the notch on the solid-state drive with the tab on the M.2 card slot. 2. Slide the solid-state drive into the M.2 card slot on the system board. 3. Replace the screw (M2x2.5) to secure the solid-state drive to the system board. Next steps 1. 2. 3. 4. 5. Install the system-board shield. Install the back cover. Install the cable cover (optional). Install the stand. Follow the procedure in After working inside your computer. System fan Removing the system fan Prerequisites 1. 2. 3. 4. 5.
Steps 1. Disconnect the system-fan cable from the system board. 2. Remove the three screws (M3x5) that secure the system fan to the display-assembly base. 3. Lift the system fan, along with its cable, off the display-assembly base. Installing the system fan Prerequisites If you are replacing a component, remove the existing component before performing the installation procedure.
Steps 1. Align the screw holes on the system fan with the screw holes on the display-assembly base. 2. Replace the three screws (M3x5) to secure the system fan to the display-assembly base. 3. Connect the system-fan cable to the connector on the system board. Next steps 1. 2. 3. 4. 5. Install the system-board shield. Install the back cover. Install the cable cover (optional). Install the stand. Follow the procedure in After working inside your computer.
Steps 1. Using the plastic scribe, press on the metal clip to release the coin-cell battery from the coin-cell battery holder. 2. Lift the coin-cell battery from the coin-cell battery holder. Installing the coin-cell battery 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 coin-cell battery and provides a visual representation of the installation procedure.
Steps With the positive-side facing up, insert the coin-cell battery into the battery holder on the system board and gently press the battery until it snaps into place. Next steps 1. 2. 3. 4. 5. Install the system-board shield. Install the back cover. Install the cable cover (optional). Install the stand. Follow the procedure in After working inside your computer. Wireless card Removing the wireless card Prerequisites 1. 2. 3. 4. 5. Follow the procedure in Before working inside your computer.
Steps 1. Remove the two screws (M2x2.5) that secure the wireless-card shield to the system board. 2. Unroute the antenna cables from the routing guides on the wireless-card shield. 3. Lift the wireless-card shield out of the system. 4. Remove the screw (M2x2.5) that secures the wireless-card bracket to the wireless card. 5. Slide and remove the wireless-card bracket off the wireless card. 6. Disconnect the antenna cables from the wireless card.
Steps 1. Connect the antenna cables to the wireless card. The following table provides the antenna-cable color scheme: Table 2. Antenna-cable color scheme Connectors on the wireless card Antenna-cable color Silkscreen marking Main White MAIN △ (white triangle) Auxiliary Black AUX ▲ (black triangle) NOTE: The antenna cables are preinstalled in your computer at the point of sale, even if you have obtained the computer without the WLAN card. 2. Place the wireless-card bracket on the wireless card.
3. Install the cable cover (optional). 4. Install the stand. 5. Follow the procedure in After working inside your computer. Camera assembly Removing the camera assembly Prerequisites 1. 2. 3. 4. 5. Follow the procedure in Before working inside your computer. Remove the stand. Remove the cable cover (optional). Remove the back cover. Remove the system-board shield.
Steps 1. Remove the two screws (M3x5) that secure the camera-assembly door to the display-assembly base. 2. Disconnect the camera cable from the connector on the system board. 3. Remove the two screws (M3x5) that secure the camera assembly to the middle frame. 4. Slide and remove the camera assembly from the middle frame. 5. Unroute the camera cable from the routing guides on the display-assembly base.
2. Slide the camera assembly on the middle frame, and align the screw holes on the camera assembly with the screw holes on the middle frame. 3. Replace the two screws (M3x5) to secure the camera assembly to the middle frame. 4. Connect the camera cable to the system board. 5. Align the screw holes on the camera door with the screw holes on the display-assembly base. 6. Replace the two screws (M3x5) to secure the camera door to the display-assembly base. Next steps 1. 2. 3. 4. 5.
Steps 1. Remove the four screws (M3x5) that secure the bottom cover to the display-assembly base. 2. Pry and lift the bottom cover off the display-assembly base. Installing the bottom cover 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 bottom cover and provides a visual representation of the installation procedure.
Steps 1. Align the screw holes on the bottom cover with the screw holes on the display-assembly base. 2. Replace the four screws (M3x5) to secure the bottom cover to the display-assembly base. Next steps 1. 2. 3. 4. 5. Install the system-board shield. Install the back cover. Install the cable cover (optional). Install the stand. Follow the procedure in After working inside your computer. Power-supply unit Removing the power-supply unit (PSU) Prerequisites 1. 2. 3. 4. 5. 6.
Steps 1. Remove the screw (M3x5) that secures the power-supply socket to the rear-I/O bracket. 2. Slide the power-supply socket out of the rear-I/O bracket. 3. Remove the power-supply cable from the routing guides on the rear-I/O bracket and PSU fan. 4. Disconnect the power-supply cable from the connector on the system board. 5. Remove the screw (M3x5) that secures the PSU to the display-assembly base. 6. Lift the PSU out of the system.
Installing the power-supply unit (PSU) 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 PSU and provides a visual representation of the PSU installation procedure.
Steps 1. Align and place the PSU in the slot on the display-assembly base. 2. Replace the screw (M3x5) to secure the PSU to the display-assembly base. 3. Connect the power-supply cable to the connector on the system board. 4. Route the power-supply cable through the routing guides on the rear-I/O bracket and PSU fan. 5. Align the screw hole on the power-supply socket with the screw hole on the rear-I/O bracket, and place it in the slot on the rear-I/O bracket. 6.
Steps 1. Remove the power-supply cable from the routing guides on the PSU fan. 2. Disconnect the PSU-fan cable from the system board. 3. Remove the two screws (M3x5) that secure the PSU fan to the display-assembly base. 4. Lift the PSU fan from the display-assembly base. Installing the PSU fan Prerequisites If you are replacing a component, remove the existing component before performing the installation procedure.
Steps 1. Align the screw holes on the PSU fan with the screw holes on the display-assembly base. 2. Replace the two screws (M3x5) to secure the PSU fan to the display-assembly base. 3. Connect the PSU-fan cable to the connector on the system board. 4. Route the power-supply cable through the routing guides on the PSU fan. Next steps 1. 2. 3. 4. 5. Install the system-board shield. Install the back cover. Install the cable cover (optional). Install the stand.
Steps 1. In reverse sequential order (as indicated on the heat sink), loosen the five captive screws that secure the heat sink to the system board and the display-assembly base. 2. Slide and lift the heat sink off the system board and display-assembly base. Installing the heat sink—UMA Prerequisites If you are replacing a component, remove the existing component before performing the installation procedure.
Steps 1. Align the screw holes on the heat sink with the screw holes on the system board and the display-assembly base. 2. In sequential order (as indicated on the heat sink), tighten the five captive screws that secure the heat sink to the system board and display-assembly base. Next steps 1. 2. 3. 4. 5. 6. Install the system fan. Install the system-board shield. Install the back cover. Install the cable cover (optional). Install the stand. Follow the procedure in After working inside your computer.
About this task The following image indicates the location of the heat sink and provides a visual representation of the heat sink removal procedure. Steps 1. In reverse sequential order (as indicated on the heat sink), loosen the nine captive screws that secure the heat sink to the system board and the display-assembly base. 2. Slide and lift the heat sink off the system board and display-assembly base.
Steps 1. Align the screw holes on the heat sink with the screw holes on the system board and the display-assembly base. 2. In sequential order (as indicated on the heat sink), tighten the nine captive screws to secure the heat sink to the system board and display-assembly base. Next steps 1. 2. 3. 4. 5. 6. Install the system fan. Install the system-board shield. Install the back cover. Install the cable cover (optional). Install the stand. Follow the procedure in After working inside your computer.
6. Remove the heat sink. About this task The following image indicates the location of the processor and provides a visual representation of the removal procedure. Steps 1. Press the release lever down and then push it away from the processor to release it from the securing tab. 2. Extend the release lever completely, and open the processor cover. CAUTION: When removing the processor, do not touch any of the pins inside the socket or allow any objects to fall on the pins in the socket. 3.
Steps 1. Ensure that the release lever on the processor socket is fully extended in the open position. NOTE: The pin-1 corner of the processor has a triangle that aligns with the triangle on the pin-1 corner on the processor socket. When the processor is properly seated, all four corners are aligned at the same height. If one or more corners of the processor are higher than the others, the processor is not seated properly. 2.
Rear-I/O bracket Removing the rear-I/O bracket Prerequisites 1. 2. 3. 4. 5. 6. Follow the procedure in Before working inside your computer. Remove the stand. Remove the cable cover (optional). Remove the back cover. Remove the system-board shield. Remove the bottom cover. About this task The following image indicates the location of the rear-I/O bracket and provides a visual representation of the removal procedure. Steps 1.
Installing the rear-I/O bracket 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 rear-I/O bracket and provides a visual representation of the installation procedure. Steps 1. Align the screw holes on the rear-I/O bracket with the screw holes on the display-assembly base. 2. Replace the three screws (M3x5) to secure the rear-I/O bracket to the display-assembly base. 3.
System board Removing the system board Prerequisites 1. Follow the procedure in Before working inside your computer. NOTE: Your computer’s Service Tag is stored in the system board. You must enter the Service Tag in the BIOS setup program after you replace the system board. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. NOTE: Replacing the system board removes any changes you have made to the BIOS using the BIOS setup program. You must make the appropriate changes again after you replace the system board.
2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. Coin-cell battery Display back-light cable connector Camera cable connector M.2 2230/2280 solid-state drive PCIe connector Processor-fan cable connector Memory modules M.2 2230/2280 solid-state drive PCIe connector Side I/O-signal cable connector Side I/O-power cable connector Audio-board cable connector Microphone-module cable connector Speaker cable connector Display cable connector M.
8. Disconnect the SIO-signal cable from the connector on the system board. 9. Disconnect the SIO-power cable from the connector on the system board. 10. Disconnect the audio-board cable from the connector on the system board. 11. Disconnect the system fan cable from the connector on the system board. 12. Disconnect the touchscreen cable from the connector on the system board. 13. Disconnect the camera cable from the connector on the system board. 14.
12. 13. 14. 15. 16. 17. 18. Microphone-module cable connector Speaker cable connector Display cable connector M.2 WLAN connector PSU-fan cable connector Touchscreen cable connector Processor The following image indicates the location of the system board and provides a visual representation of the installation procedure. Steps 1. Align the screw holes on the system board with the screw holes on the display-assembly base. 2.
NOTE: Ensure the display back-light cable is routed under the system board and not to the side of the system board to avoid the cable getting caught between the system board and the camera. This damages the cable, and the camera may not lock in a closed position. Next steps 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. Install the rear-I/O bracket. Install the bottom cover. Install the coin-cell battery. Install the processor. Install the heat sink. Install the M.2 solid-state drive.
Steps 1. Disconnect the speaker cable from the connector on the system board. 2. Remove the six screws (M3 4+7.1xZN) that secure the speakers to the display-assembly base. 3. Remove the speaker cable from the routing guides on the display-assembly base. 4. Lift the speakers along with the cable off the display-assembly base. Installing the speakers Prerequisites If you are replacing a component, remove the existing component before performing the installation procedure.
Steps 1. Align the screw holes on the speakers with the screw holes on the display-assembly base. 2. Replace the six screws (M3 4+7.1xZN) to secure the speakers to the display-assembly base. 3. Route the speaker cable through the routing guide on display-assembly base and connect the speaker cable to the system board. Next steps 1. 2. 3. 4. 5. 6. 7. Install the rear-I/O bracket. Install the bottom cover. Install the system-board shield. Install the back cover. Install the cable cover (optional).
Steps 1. Open the latch and disconnect the power-button cable from the connector on the system board. 2. Remove the screw (M3x5) that secures the power-button board to the middle frame. 3. Lift the power-button board along with cable off the middle frame. Installing the power-button board Prerequisites If you are replacing a component, remove the existing component before performing the installation procedure.
Steps 1. Align and place the power-button board in the slot on the middle frame. 2. Replace the screw (M3x5) to secure the power-button board to the middle frame. 3. Slide the power-button cable into the connector on the system board and close the latch to secure the cable. Next steps 1. 2. 3. 4. 5. 6. 7. 8. Install the speakers. Install the rear-I/O bracket. Install the bottom cover. Install the system-board shield. Install the back cover. Install the cable cover (optional). Install the stand.
6. Remove the bottom cover. 7. Remove the rear-I/O bracket. 8. Remove the speakers. About this task The following image indicates the location of the microphones and provides a visual representation of the removal procedure. Steps 1. Disconnect the microphone cable from the system board, and unroute it from the routing guides on the display-assembly base. 2. Remove the two screws (M2x2.5) that secure the microphone modules to the middle frame. 3.
Installing the microphones 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 microphones and provides a visual representation of the installation procedure. Steps 1. Align the screw holes on the microphone modules with the screw holes on the middle frame. 2. Replace the two screws (M2X2.5) to secure the microphone modules to the middle frame. 3.
Next steps 1. 2. 3. 4. 5. 6. 7. 8. Install the speakers. Install the rear-I/O bracket. Install the bottom cover. Install the system-board shield. Install the back cover. Install the cable cover (optional). Install the stand. Follow the procedure in After working inside your computer. Side I/O-board Removing the side I/O-board Prerequisites 1. 2. 3. 4. 5. 6. 7. Follow the procedure in Before working inside your computer. Remove the stand. Remove the cable cover (optional). Remove the back cover.
Steps 1. Remove the two screws (M3x5) that secure the side I/O-board shield to the display-assembly base. 2. Lift and remove the side I/O-board shield off the side I/O-board. 3. Disconnect the SIO-signal cable, SIO-power cable, and audio-board cable from the system board. 4. Remove the SIO-signal cable, SIO-power cable, and audio-board cable from the routing guides on the display-assembly base. 5. Remove the two screws (M2.5x3.5) that secure the side I/O-board to the display-assembly base. 6.
Steps 1. Align the screw holes on the side I/O-board with the screw holes on the display-assembly base. 2. Replace the two screws (M2.5x3.5) to secure the side I/O-board to the display-assembly base. 3. Route the SIO-signal cable, SIO-power cable, and audio-board cable through the routing guides on the display-assembly base. 4. Connect the SIO-signal cable, SIO-power cable, and audio-board cable to the connectors on the system board. 5.
Audio board Removing the audio board Prerequisites 1. 2. 3. 4. 5. 6. 7. 8. Follow the procedure in Before working inside your computer. Remove the stand. Remove the cable cover (optional). Remove the back cover. Remove the system-board shield. Remove the bottom cover. Remove the rear-I/O bracket. Remove the side-I/O board. About this task The following image indicates the location of the audio board and provides a visual representation of the installation procedure. Steps 1.
Steps 1. Align the screw hole on the audio board with the screw hole on the display-assembly base. 2. Replace the screw (M3x5) to secure the audio board to the display-assembly base. 3. Connect the audio-board cable to the system board. Next steps 1. 2. 3. 4. 5. 6. 7. 8. Install the side-I/O board. Install the rear-I/O bracket. Install the bottom cover. Install the system-board shield. Install the back cover. Install the cable cover (optional). Install the stand.
Steps 1. Remove the antenna cables from the routing guides on the display-assembly base. 2. Remove the two screws (M2x2.5) that secure the antenna modules to the middle frame. 3. Carefully peel the copper foil that secures the antenna cables to the middle frame. 4. Lift the antenna modules off the middle frame. Installing the antenna modules Prerequisites If you are replacing a component, remove the existing component before performing the installation procedure.
Steps 1. Align and place the antenna modules in the slots on the middle frame. 2. Adhere the copper foil that secures the antenna cables to the middle frame. 3. Replace the two screws (M2x2.5) to secure the antenna modules to the middle frame. 4. Route the antenna cables through the routing guides on the display-assembly base. Next steps 1. 2. 3. 4. 5. 6. 7. 8. 9. Install the speakers. Install the rear-I/O bracket. Install the bottom cover. Install the wireless card. Install the system-board shield.
9. 10. 11. 12. Remove Remove Remove Remove the the the the camera assembly. system board. PSU fan. PSU. About this task The following image indicates the location of the display panel and provides a visual representation of the display panel removal procedure.
Steps 1. Remove the 11 screws (M3x5) (for touch display) and 12 screws (M3x5) (for non-touch display) that secure the display panel to the middle frame and display-assembly base. 2. Unroute the display back-light cable from the routing guides on the display-assembly base. 3. Place the system in an upright position. 4. Holding the top corner, release the display panel away from the middle frame and display-assembly base. 5.
Steps 1. Place the system in an upright position, and slide the display panel on the slots of the display-assembly base. 2. Route the display-backlight, and display cable through the slots on the display-assembly base.
3. Place the display-assembly base on a clean and flat surface with the display panel facing down. 4. Replace the nine screws (M3x5) (for touch display) and ten screws (M3x5) (for non-touch display) to secure the display panel to the middle frame and display-assembly base. 5. Remove the two jig screws from the display panel and replace with two screws (M3x5) to secure the display panel to the middle frame and display assembly base. NOTE: The jig screw is shipped with the replacement display panel.
Steps 1. Remove the 17 screws (M3x5) that secure the middle frame to the display-assembly base. 2. Remove the middle frame and lift the middle frame off the display-assembly base. Installing the middle frame 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 middle frame and provides a visual representation of the middle frame installation procedure.
Steps 1. Slide and align the middle frame to the slots on the display-assembly base, then snap the middle frame into place on the display-assembly base. 2. Replace the 17 screws (M3x5) to secure the middle frame to the display-assembly base. Next steps 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 82 Install the display panel. Install the antenna modules. Install the side-I/O board. Install the PSU. Install the PSU fan. Install the microphones. Install the power-button board.
3 Drivers and downloads When troubleshooting, downloading or installing drivers it is recommended that you read the Dell Knowledge Based article, Drivers and Downloads FAQ 000123347.
4 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.
The one-time boot menu displays the devices that you can boot from including the diagnostic option. The boot menu options are: ● Removable Drive (if available) ● STXXXX Drive (if available) NOTE: XXX denotes the SATA drive number. ● Optical Drive (if available) ● SATA Hard Drive (if available) ● Diagnostics The boot sequence screen also displays the option to access the System Setup screen.
Table 4. System setup options—System information menu (continued) Overview DIMM_SLOT 1 Displays the DIMM 1 memory size. DIMM_SLOT 2 Displays the DIMM 2 memory size. Devices Information Panel Type Displays the Panel Type of the computer. Video Controller Displays the video controller type of the computer. Video Memory Displays the video memory information of the computer. Wi-Fi Device Displays the wireless device information of the computer.
Table 6. System setup options—Integrated Devices menu (continued) Integrated Devices Audio Enable Audio Enable or disable the integrated audio controller. By default, all the options are enabled. USB Configuration ● Enable or disable booting from USB mass storage devices through the boot sequence or boot menu. By default, all the options are enabled. Side USB Configuration Enable or disable the individual side USB ports.
Table 8. System setup options—Display menu Display OSD Button Management Disable OSD Buttons Enable or disable the OSD (On-Screen Display) buttons on the computer. Full Screen Logo Enable or disable full screen logo. By default, the option is not enabled. Table 9. System setup options—Connection menu Connection Network Controller Configuration Integrated NIC Controls the on-board LAN controller. By default, the Enabled with PXE option is enabled.
Table 10. System setup options—Power menu (continued) Power By default, the Enabled in S4 and S5 option is enabled. Fan Control Override Enable or disable the fan control override feature. By default, the option is disabled. Intel Speed Shift Technology Enable or disable the Intel speed shift technology support. By default, the Intel Speed Shift Technology option is enabled. Table 11. System setup options—Security menu Security TPM 2.0 Security TPM 2.0 Security On Enable or disable TPM 2.
Table 12. System setup options—Passwords menu Passwords Admin Password Set, change, or delete the administrator password. System Password Set, change, or delete the computer password. NVMe SSD0 Set, change, or delete the NVMe SSD0 password. Password Configuration Upper Case Letter Reinforces password must have at least one upper case letter. By default, the option is disabled. Lower Case Letter Reinforces password must have at least one lower case letter. By default, the option is disabled.
Table 13. System setup options—Update, Recovery menu (continued) Update, Recovery Allow BIOS Downgrade Enable or disable the flashing of the computer firmware to previous revision is blocked. By default, the option is enabled. SupportAssist OS Recovery Enable or disable the boot flow for SupportAssist OS Recovery tool in the event of certain computer errors. By default, the option is enabled.
Table 15. System setup options—Keyboard menu Keyboard Keyboard Errors Enable Keyboard Error Detection Enable or disable the keyboard error detection. By default, the option is enabled. Numlock LED Enable Numlock LED Enable or disable Numlock LED. By default, the option is enabled. Table 16. System setup options—Pre-boot Behavior menu Pre-boot Behavior Warning and Errors Enable or disable the action to be done when a warning or error is encountered.
Table 18. System setup options—Performance menu (continued) Performance Enable C-State Control Enable or disable additional processor sleep states. By default, the option is enabled. Intel Turbo Boost Technology Enable Intel Turbo Boost Technology Enable or disable Intel TurboBoost mode of the processor. By default, the option is enabled. Intel Hyper-Threading Technology Enable Intel Hyper-Threading Technology Enable or disable Hyper-Threading in the processor. By default, the option is enabled.
Updating the BIOS using the USB drive in Windows About this task CAUTION: If BitLocker is not suspended before updating the BIOS, the next time you reboot the system it will not recognize the BitLocker key. You will then be prompted to enter the recovery key to progress and the system will ask for this on each reboot. If the recovery key is not known this can result in data loss or an unnecessary operating system re-install. For more information on this subject, see Knowledge Article: https:// www.dell.
Steps 1. From a turn off state, insert the USB drive where you copied the flash into a USB port of the computer. 2. Turn on the computer and press F12 to access the One-Time Boot Menu, select BIOS Update using the mouse or arrow keys then press Enter. The flash BIOS menu is displayed. 3. Click Flash from file. 4. Select external USB device. 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.
Deleting or changing an existing system setup password Prerequisites Ensure that the Password Status is Unlocked (in the System Setup) before attempting to delete or change the existing System and/or Setup password. You cannot delete or change an existing System or Setup password, if the Password Status is Locked. About this task To enter the System Setup, press F12 immediately after a power-on or reboot. Steps 1. In the System BIOS or System Setup screen, select System Security and press Enter.
5 Troubleshooting Dell SupportAssist Pre-boot System Performance 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.
5. Hold the display built-in self test button until the test starts. Power-Supply Unit Built-in Self-Test Built-in Self-Test (BIST) helps determine if the power-supply unit is working. To run self-test diagnostics on the power-supply unit of a desktop or all-in-one computer, see the knowledge base article 000125179 at www.dell.com/support. System-diagnostic lights This section lists the system-diagnostic lights of your OptiPlex 7400 All-in-One. Table 21.
Table 21. System-diagnostic lights (continued) Blinking pattern Amber White Problem description Suggested resolution 2 8 LCD failure (EC detection of power rail failure) Replace the system board. 3 1 CMOS battery failure ● ● Reset the main battery connection. If problem persists, replace the main battery. 3 2 PCI or Video card/chip failure 3 3 BIOS Recovery image not found ● ● Flash latest BIOS version If problem persists, replace the system board.
Real Time Clock—RTC reset The Real Time Clock (RTC) reset function allows you or the service technician to recover the recently launched model Dell Latitude and Precision systems from No POST/No Boot/No Power situations. You can initiate the RTC reset on the system from a power-off state only if it is connected to AC power. Press and hold the power button for 25 seconds. The system RTC reset occurs after you release the power button.
6 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 22. Self-help resources Self-help resources Resource location Information about Dell products and services www.dell.com My Dell app Tips Contact Support In Windows search, type Contact Support, and press Enter. Online help for operating system www.dell.com/support/windows www.dell.
