Dell Inspiron 7791 2n1 operation manual

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Inspiron 7791 2n1

Service Manual

Regulatory Model: P42E

Regulatory Type: P42E001

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.

© 2018 - 2019 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.

2019 - 08

Rev. A00

Contents

1 Working inside your computer.......................................................................................................	5
Safety instructions................................................................................................................................................................	5
Before working inside your computer.................................................................................................................................	5
Before you begin .............................................................................................................................................................	5
Electrostatic discharge—ESD protection..........................................................................................................................	6
ESD field service kit ..............................................................................................................................................................	6
Transporting sensitive components....................................................................................................................................	7
After working inside your computer....................................................................................................................................	7
2 Removing and installing components.............................................................................................	8
Recommended tools..............................................................................................................................................................	8
Screw list................................................................................................................................................................................	8
Base cover..............................................................................................................................................................................	9
Removing the base cover...............................................................................................................................................	9
Installing the base cover.................................................................................................................................................	11
Battery...................................................................................................................................................................................	13
Lithium-ion battery precautions...................................................................................................................................	13
Removing the battery....................................................................................................................................................	13
Installing the battery......................................................................................................................................................	14
Memory modules..................................................................................................................................................................	15
Removing the memory modules...................................................................................................................................	15
Installing the memory modules.....................................................................................................................................	16
Wireless card.........................................................................................................................................................................	18
Removing the wireless card..........................................................................................................................................	18
Installing the wireless card............................................................................................................................................	18
Coin-cell battery...................................................................................................................................................................	19
Removing the coin-cell battery....................................................................................................................................	19
Installing the coin-cell battery......................................................................................................................................	20
Hard drive..............................................................................................................................................................................	21
Removing the hard drive...............................................................................................................................................	21
Installing the hard drive.................................................................................................................................................	22
Fan.........................................................................................................................................................................................	24
Removing the fan..........................................................................................................................................................	24
Installing the fan.............................................................................................................................................................	25
Touchpad..............................................................................................................................................................................	26
Removing the touchpad...............................................................................................................................................	26
Installing the touchpad..................................................................................................................................................	27
Power-adapter port.............................................................................................................................................................	27
Removing the power-adapter port..............................................................................................................................	27
Installing the power-adapter port................................................................................................................................	28
Speakers...............................................................................................................................................................................	29
Removing the speakers................................................................................................................................................	29
Installing the speakers...................................................................................................................................................	30
Heat sink................................................................................................................................................................................	31

Contents 3

Removing the heatsink..................................................................................................................................................	31
Installing the heatsink....................................................................................................................................................	32
Display assembly..................................................................................................................................................................	33
Removing the display assembly...................................................................................................................................	33
Installing the display assembly......................................................................................................................................	36
I/O board..............................................................................................................................................................................	39
Removing the I/O board...............................................................................................................................................	39
Installing the I/O board.................................................................................................................................................	39
System board.......................................................................................................................................................................	40
Removing the system board........................................................................................................................................	40
Installing the system board...........................................................................................................................................	42
Keyboard bracket................................................................................................................................................................	45
Removing the keyboard bracket..................................................................................................................................	45
Installing the keyboard bracket....................................................................................................................................	47
Keyboard...............................................................................................................................................................................	48
Removing the keyboard................................................................................................................................................	48
Installing the keyboard..................................................................................................................................................	49
Power button with fingerprint reader................................................................................................................................	51
Removing the power button with fingerprint reader.................................................................................................	51
Installing the power button with fingerprint reader..................................................................................................	52
Palm-rest and antenna assembly......................................................................................................................................	53
Removing the palm-rest and antenna assembly.......................................................................................................	53
Installing the palm-rest and antenna assembly..........................................................................................................	54
3 Device drivers............................................................................................................................	55
Downloading the audio driver............................................................................................................................................	55
Downloading the network driver.......................................................................................................................................	55
Downloading the chipset driver.........................................................................................................................................	56
Downloading the media-card reader driver......................................................................................................................	56
Downloading the WiFi driver..............................................................................................................................................	57
Downloading the USB driver..............................................................................................................................................	57
Downloading the graphics driver.......................................................................................................................................	58
4 Troubleshooting.........................................................................................................................	59
Enhanced Pre-Boot System Assessment (ePSA) diagnostics......................................................................................	59
Running the ePSA diagnostics.....................................................................................................................................	59
System diagnostic lights.....................................................................................................................................................	59
Recovering the operating system.....................................................................................................................................	60
Flashing BIOS (USB key)...................................................................................................................................................	60
Flashing the BIOS.................................................................................................................................................................	61
WiFi power cycle..................................................................................................................................................................	61
Flea power release...............................................................................................................................................................	61
5 Getting help and contacting Dell..................................................................................................	63

4 Contents

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.

NOTE: Before working inside your computer, read the safety information that shipped with your computer. For more safety best practices, see the Regulatory Compliance home page at www.dell.com/regulatory_compliance.

NOTE: Disconnect all power sources before opening the computer cover or panels. After you finish working inside the computer, replace all covers, panels, and screws before connecting to the electrical outlet.

CAUTION: To avoid damaging the computer, ensure that the work surface is flat and clean.

CAUTION: Handle components and cards with care. Do not touch the components or contacts on a card. Hold a card by its edges or by its metal mounting bracket. Hold a component such as a processor by its edges, not by its pins.

CAUTION: You should only perform troubleshooting and repairs as authorized or directed by the Dell technical assistance team. Damage due to servicing that is not authorized by Dell is not covered by your warranty. See the safety instructions that shipped with the product or at www.dell.com/regulatory_compliance.

CAUTION: Before touching anything inside your computer, ground yourself by using a wrist grounding strap or by periodically touching an unpainted metal surface, such as the metal at the back of the computer. While you work, periodically touch an unpainted metal surface to dissipate static electricity, which could harm internal components.

CAUTION: When you disconnect a cable, pull on its connector or on its pull tab, not on the cable itself. Some cables have connectors with locking tabs or thumb-screws that you must disengage before disconnecting the cable. When disconnecting cables, keep them evenly aligned to avoid bending any connector pins. When connecting cables, ensure that the ports and connectors are correctly oriented and aligned.

CAUTION: Press and eject any installed card from the media-card reader.

NOTE: The color of your computer and certain components may appear differently than shown in this document.

Before working inside your computer

NOTE: The images in this document may differ from your computer depending on the configuration you ordered.

Before you begin

Steps

1.Save and close all open files and exit all open applications.

2.Shut down your computer. Click Start > Power > Shut down.

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.

Working inside your computer

Electrostatic discharge—ESD protection

ESD is a major concern when you handle electronic components, especially sensitive components such as expansion cards, processors, memory DIMMs, and system boards. Very slight charges can damage circuits in ways that may not be obvious, such as intermittent problems or a shortened product life span. As the industry pushes for lower power requirements and increased density, ESD protection is an increasing concern.

Due to the increased density of semiconductors used in recent Dell products, the sensitivity to static damage is now higher than in previous Dell products. For this reason, some previously approved methods of handling parts are no longer applicable.

Two recognized types of ESD damage are catastrophic and intermittent failures.

•Catastrophic – Catastrophic failures represent approximately 20 percent of ESD-related failures. The damage causes an immediate and complete loss of device functionality. An example of catastrophic failure is a memory DIMM that has received a static shock and immediately generates a "No POST/No Video" symptom with a beep code emitted for missing or nonfunctional memory.

•Intermittent – Intermittent failures represent approximately 80 percent of ESD-related failures. The high rate of intermittent failures means that most of the time when damage occurs, it is not immediately recognizable. The DIMM receives a static shock, but the tracing is merely weakened and does not immediately produce outward symptoms related to 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. Touching the chassis before handling parts does not ensure adequate ESD protection on parts with increased sensitivity to ESD damage.

•Handle all static-sensitive components in a static-safe area. If possible, use anti-static floor pads and workbench pads.

•When unpacking a static-sensitive component from its shipping carton, do not remove the component from the anti-static packing material until you are ready to install the component. Before unwrapping the anti-static packaging, ensure that you discharge static electricity from your body.

•Before transporting a static-sensitive component, place it in an anti-static container or packaging.

ESD field service kit

The unmonitored Field Service kit is the most commonly used service kit. Each Field Service kit includes three main components: antistatic mat, wrist strap, and bonding wire.

Components of an ESD field service kit

The components of an ESD field service kit are:

•Anti-Static Mat – The anti-static mat is dissipative and parts can be placed on it during service procedures. When using an antistatic mat, your wrist strap should be snug and the bonding wire should be connected to the mat and to any bare metal on the system being worked on. Once deployed properly, service parts can be removed from the ESD bag and placed directly on the mat. ESDsensitive items are safe in your hand, on the ESD mat, in the system, or inside a bag.

•Wrist Strap and Bonding Wire – The wrist strap and bonding wire can be either directly connected between your wrist and bare metal on the hardware if the ESD mat is not required, or connected to the anti-static mat to protect hardware that is temporarily placed on the mat. The physical connection of the wrist strap and bonding wire between your skin, the ESD mat, and the hardware is known as bonding. Use only Field Service kits with a wrist strap, mat, and bonding wire. Never use wireless wrist straps. Always be aware that the internal wires of a wrist strap are prone to damage from normal wear and tear, and must be checked regularly with a wrist strap tester in order to avoid accidental ESD hardware damage. It is recommended to test the wrist strap and bonding wire at least once per week.

•ESD Wrist Strap Tester – The wires inside of an ESD strap are prone to damage over time. When using an unmonitored kit, it is a best practice to regularly test the strap prior to each service call, and at a minimum, test once per week. A wrist strap tester is the best method for doing this test. If you do not have your own wrist strap tester, check with your regional office to find out if they have one. To perform the test, plug the wrist-strap's bonding-wire into the tester while it is strapped to your wrist and push the button to test. A green LED is lit if the test is successful; a red LED is lit and an alarm sounds if the test fails.

•Insulator Elements – It is critical to keep ESD sensitive devices, such as plastic heat sink casings, away from internal parts that are insulators and often highly charged.

•Working Environment – Before deploying the ESD Field Service kit, assess the situation at the customer location. For example, deploying the kit for a server environment is different than for a desktop or portable environment. Servers are typically installed in a rack within a data center; desktops or portables are typically placed on office desks or cubicles. Always look for a large open flat work area that is free of clutter and large enough to deploy the ESD kit with additional space to accommodate the type of system that is being repaired. The workspace should also be free of insulators that can cause an ESD event. On the work area, insulators such as

6 Working inside your computer

Styrofoam and other plastics should always be moved at least 12 inches or 30 centimeters away from sensitive parts before physically handling any hardware components

•ESD Packaging – All ESD-sensitive devices must be shipped and received in static-safe packaging. Metal, static-shielded bags are preferred. However, you should always return the damaged part using the same ESD bag and packaging that the new part arrived in. The ESD bag should be folded over and taped shut and all the same foam packing material should be used in the original box that the new part arrived in. ESD-sensitive devices should be removed from packaging only at an ESD-protected work surface, and parts should never be placed on top of the ESD bag because only the inside of the bag is shielded. Always place parts in your hand, on the ESD mat, in the system, or inside an anti-static bag.

•Transporting Sensitive Components – When transporting ESD sensitive components such as replacement parts or parts to be returned to Dell, it is critical to place these parts in anti-static bags for safe transport.

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.

Transporting sensitive components

When transporting ESD sensitive components such as replacement parts or parts to be returned to Dell, it is critical to place these parts in anti-static bags for safe transport.

Lifting equipment

Adhere to the following guidelines when lifting heavy weight equipment:

CAUTION: Do not lift greater than 50 pounds. Always obtain additional resources or use a mechanical lifting device.

1.Get a firm balanced footing. Keep your feet apart for a stable base, and point your toes out.

2.Tighten stomach muscles. Abdominal muscles support your spine when you lift, offsetting the force of the load.

3.Lift with your legs, not your back.

4.Keep the load close. The closer it is to your spine, the less force it exerts on your back.

5.Keep your back upright, whether lifting or setting down the load. Do not add the weight of your body to the load. Avoid twisting your body and back.

6.Follow the same techniques in reverse to set the load down.

After working inside your computer

About this task

CAUTION: 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.Replace any media cards, discs, or any other parts that you removed before working on your computer.

4.Connect your computer and all attached devices to their electrical outlets.

5.Turn on your computer.

Working inside your computer

Removing and installing components

Recommended tools

The procedures in this document may require the following tools:

•Philips screwdriver #1

•Flat-head screwdriver

•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. This is to ensure that the correct number of screws and correct screw type is restored when the component is replaced.

NOTE: Some computers have magnetic surfaces. Ensure that the screws are not left attached to such surface when replacing a component.

NOTE: Screw color may vary with the configuration ordered.

Table 1. Screw list

Component	Secured to	Screw type	Quantity	Screw image

Base cover	Palm-rest and antenna	M2x4	8
	assembly

Battery	Palm-rest and antenna	M2x3	2
	assembly

Wireless-card bracket	Wireless card and Palm-rest	M2x3	1
	and antenna assembly

Right-display hinge	I/O board	M2.5x5	3

I/O board	Palm-rest and antenna	M2x4	1
	assembly

Display-cable bracket	Palm-rest and antenna	M2x3	2
	assembly

Fan	Palm-rest and antenna	M2x3	2
	assembly

Hard-drive assembly	Palm-rest and antenna	M2x3	3
	assembly

Hard-drive bracket	Hard drive	M3x3	4

Touch-pad bracket	Palm-rest and antenna	M2x3	3
	assembly

Touchpad	Palm-rest and antenna	M1.6x2	2
	assembly

8 Removing and installing components

Component	Secured to	Screw type	Quantity	Screw image

Left-display hinge	System board	M2.5x5	2

Power-adapter port	Palm-rest and antenna	M2x3	1
	assembly

System board	Palm-rest and antenna	M2x2	2
	assembly

Keyboard bracket	Palm-rest and antenna	M1.2x1.8	37
	assembly

Keyboard	Palm-rest and antenna	M1.2x1.5	5
	assembly

Base cover

Removing the base cover

Prerequisites

1. Follow the procedure in Before working inside your computer.

About this task

The following image indicates the location of the base cover and provides a visual representation of the removal procedure.

Removing and installing components

Steps

1.Loosen the three captive screws that secure the base cover to the palm-rest assembly.

2.Remove the eight screws (M2x4) that secure the base cover to the palm-rest assembly.

3.Using a plastic scribe, pry the base cover starting from the hinges and continue to pry the base cover from the slots on the palm-rest assembly.

CAUTION: Do not pry the base cover from the middle as it might damage the chassis.

4.Carefully remove the base cover off the palm-rest assembly.

10 Removing and installing components

5. Disconnect the battery cable from the system board.

Installing the base 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 base cover and provides a visual representation of the installation procedure.

Removing and installing components

12 Removing and installing components

Steps

1.Connect the battery cable to the system board.

2.Align the tabs on the base cover with the slots on the palm-rest assembly and snap the base cover to the palm-rest assembly.

3.Replace the eight screws (M2x4) that secure the base cover to the palm-rest and keyboard assembly.

4.Tighten the three captive screws that secure the base cover to the palm-rest and keyboard assembly.

Next steps

1. Follow the procedure in After working inside your computer.

Battery

Lithium-ion battery precautions

CAUTION:

•Exercise caution when handling Lithium-ion batteries.

•Discharge the battery as much as possible before removing it from the system. This can be done by disconnecting the AC adapter from the system to allow the battery to drain.

•Do not crush, drop, mutilate, or penetrate the battery with foreign objects.

•Do not expose the battery to high temperatures, or disassemble battery packs and cells.

•Do not apply pressure to the surface of the battery.

•Do not bend the battery.

•Do not use tools of any kind to pry on or against the battery.

•Ensure any screws during the servicing of this product are not lost or misplaced, to prevent accidental puncture or damage to the battery and other system components.

•If a battery gets stuck in a device as a result of swelling, do not try to free it as puncturing, bending, or crushing a Lithium-ion battery can be dangerous. In such an instance, contact for assistance and further instructions.

•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.

•Always purchase genuine batteries from www.dell.com or authorized Dell partners and resellers.

Removing the battery

Prerequisites

1.Follow the procedure in Before working inside your computer.

2.Remove the base cover.

About this task

The following image indicates the location of the battery and provides a visual representation of the removal procedure.

Removing and installing components

Steps

1.Disconnect the battery cable from the system board.

2.Remove the two screws (M2x3) that secure the battery to the palm-rest assembly.

3.Loosen the captive screw that secures the battery to the palm-rest assembly.

4.Lift the battery off the palm-rest assembly.

Installing the 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 battery and provides a visual representation of the installation procedure.

14 Removing and installing components

Steps

1.Using the alignment posts, place the battery on the palm-rest assembly.

2.Replace the two screws (M2x3) that secure the battery to the palm-rest and keyboard assembly.

3.Tighten the captive screw that secures the battery to the palm-rest assembly.

4.Connect the battery cable to the system board.

Next steps

1.Install the base cover.

2.Follow the procedure in After working inside your computer.

Memory modules

Removing the memory modules

Prerequisites

1.Follow the procedure in Before working inside your computer.

2.Remove the base cover.

About this task

The following image indicates the location of the base cover and provides a visual representation of the removal procedure.

Removing and installing components

Steps

1.Lift the flap to access the memory module.

2.Use your fingertips to carefully spread apart the securing-clips on each end of 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 to step 3 to remove any other memory modules installed in your computer.

Installing the memory modules

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 base cover and provides a visual representation of the installation procedure.

16 Removing and installing components

Steps

1.Lift the flap to access the memory-module slot.

2.Align the notch on the memory module with the tab on the memory-module slot.

3.Slide the memory module firmly at an angle, into the memory-module slot.

4.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 2 to step 4 to install any other memory modules in your computer.

Next steps

1.Install the base cover.

2.Follow the procedure in After working inside your computer.

Removing and installing components

Wireless card

Removing the wireless card

Prerequisites

1.Follow the procedure in Before working inside your computer.

2.Remove the base cover.

About this task

The following image indicates the location of the base cover and provides a visual representation of the removal procedure.

Steps

1.Remove the screw (M2x3) that secures the wireless-card bracket to the wireless card and palm-rest assembly.

2.Remove the wireless-card bracket from the wireless card.

3.Disconnect the antenna cables from the wireless card.

4.Slide and remove the wireless card from the wireless-card slot.

Installing the wireless 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 base cover and provides a visual representation of the installation procedure.

18 Removing and installing components

Steps

1.Connect the antenna cables to the wireless card.

The following table provides the antenna-cable color scheme for the wireless card that is supported by your computer.

Table 2. Antenna-cable color scheme

Connectors on the wireless card	Antenna-cable color

Main (white triangle)	White

Auxiliary (black triangle)	Black

2.Align the notch on the wireless card with the tab on the wireless-card slot and insert the wireless card at an angle into the wirelesscard slot.

3.Align the screw hole on the wireless-card bracket with the screw hole on the wireless card and palm-rest assembly.

4.Replace the screw (M2x3) that secures the wireless-card bracket to the wireless card and palm-rest assembly.

Next steps

1.Install the base cover.

2.Follow the procedure in After working inside your computer.

Coin-cell battery

Removing the coin-cell battery

Prerequisites

1. Follow the procedure in Before working inside your computer.

NOTE: Removing the I/O-board cable is equivalent to removing the coin-cell battery. It resets the BIOS setup program's settings to default. It is recommended that you note the BIOS setup program's settings before removing the coin-cell battery.

2.Remove the base cover.

3.Remove the battery.

Removing and installing components

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