Given a scenario, troubleshoot and repair common mobile device issues while adhering to the appropriate procedure: CompTIA A+ Exam 220-901 sub-objective 4.5

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Detailed (and official) description of CompTIA A+ sub-objective 4.5:

4.5 Given a scenario, troubleshoot and repair common mobile device issues while adhering to the appropriate procedures.

Common symptoms
No display
Dim display
Flickering display
Sticking keys
Intermittent wireless
Battery not charging
Ghost cursor/pointer drift
No power
Num lock indicator lights
No wireless connectivity
No Bluetooth connectivity
Cannot display to external monitor
Touchscreen non-responsive
Apps not loading
Slow performance
Unable to decrypt email
Extremely short battery life
Overheating
Frozen system
No sound from speakers
GPS not functioning
Swollen battery

Disassembling processes for proper re-assembly
Document and label cable and screw locations
Organize parts
Refer to manufacturer resources
Use appropriate hand tools

Common symptoms

Many mobile device problems have simple solutions that are really easy to diagnose and the repair is just as simple. Remember that whatever it is you are working on you are smarter than it is, before you turn it on. Mobile devices add a degree of difficulty when you are working inside the enclosure everything is smaller and harder to manage. So, take your time establish a distraction free environment to work in, give yourself a stable clean work area, lay out your tools and containers for small parts. AND Relax! We’ll start by looking at group of related problems and then identifying the part that needs repair/replacement or adjustment.

More often than not when you encounter display problem on a mobile device diagnosis is usually simple the repair is another matter.

No display

In this condition the simplest way to start the laptop and if you are lucky, resolve the problem, is by checking your monitor function key combination. Determine the keystrokes and cycle through them. If the LCD doesn’t begin to display then your next step would be to get a known good external monitor and connect it. If it works you are in great shape!

Dim display

The worst case on this one is replacing the backlight but let’s not get ahead of ourselves. Relax the knee jerk reaction is to replace the backlight, take a step back look for the brightness controller. Then look on the keyboard for a brightness button or slider. If that does not work try uninstalling the video drivers in Device Manage check for hewer version of the driver manufacturer’s website and install it. Also keep in mind that some laptops are configured to dim the display when the unit is switched to battery power.

Flickering display

For this problem you would take the steps listed above also you need to check the display properties for the brightness setting and Refresh rate. Double check the connections. A low refresh rate will cause this condition if it still doesn’t work, it is either a failed inverter, backlight or LCD panel. Research the costs involved in replacing the components VS replacing the device. It might be time for an upgrade. Below is a look at a typical inverter board.

Photo of an Inverter Board
Inverter Board

This is a relatively easy replacement as it is fairly easy to access,

Ghost Cursor cannot display to external monitor

Here are more potential device driver issues. Toggle through the Function key for the display. Also when using an external monitor, make sure the cables you are using are good.

Sticking keys

If the keys on your mobile device are sticking, the first thing to try is compressed air. If that doesn’t work use contact cleaner. If that fails replace the keyboard.

No power/Battery not charging

Your battery indicator should look something like this. Our example is slightly discharged, but the indicator should read 100% when fully charged

Screenshot of a Battery indicator
Battery indicator

If you suspect that your battery is not charging there is a simple test for this. Check the green light on the AC adapter. Check that the battery is not overheated. Make sure the battery is not swollen. If the signs are good let the battery charge for a reasonable period of time, then remove the AC adapter and attempt to power up the machine.  If it works all is well. If it does not remove all power from the machine and try using only the AC Adapter. If that works you have a dead battery.

Num lock indicator lights

It is entirely possible that you will come across a laptop that behaves oddly with some of the Alpha characters displaying numbers when typed. This is a design enhancement enabling those who have a large amount of data to input on a small laptop to use the function keys to arrange the values of some of the keys into the shape of a numeric keypad and performing like a calculator. You will see this most often as a trouble call where a user inadvertently activated the function. When the function is activated the Num lock indicator light on the keyboard will be on. Repeat the keystroke to deactivate the function.

Photo of green num lock led on
Num lock led green

If there is a numeric keypad present Num Lock will toggle those keys between numeric and the other values shown.

No wireless connectivity

When “No Network” is reported by a user you have to determine whether it is a local host, network, internet or e-mail problem.

The first thing to look at is the state of the wireless card on the host, the user may have inadvertently turned it off There should be a button or switch with an indicator light. When the light is on open a Command Prompt window. Try pinging a known good host. If it fails continue. Use the information from ipconfig to determine if you got an address assigned by your DHCP server or an APIPA address. If APIPA, you didn’t connect. Release and renew your IP address. Use the ipconfig /release command to clear the IP address data then use ipconfig /renew to attain a new configuration.

Intermittent wireless

Here is another variation on that problem. This time the connection is unreliable. In this case if you have a wireless locator move around the workspace until you get the best signal. Make sure the location is practical for the user. Try to find the best balance. Often repositioning the lid slightly will get you a stronger signal. If there are a few users having this issue you have a strong case to place a low power WAP on an accessible location.

No Bluetooth connectivity

Bluetooth is a great method of creating small personal networks. Before you start an installation make sure your OS and portable device software is up to date. That’s to say if you have a headset that came with a disk, go to the manufacturer’s website and see if there is something newer, but not Beta. Bluetooth technology has saved an inestimable number of lives with the automotive implementation of the Hands-Free headset alone. Once properly configured paired Bluetooth devices seek each other out when powered up. Now to communicate with each other the devices need to be paired with each other. This is usually where the problem comes in. There is no hard and fast standard for connecting Bluetooth devices. Having the documentation is crucial. Read and understand it before you start. You may need to create or use passcodes to pair two devices. The passcodes I’ve seen so far are mere technicalities, like 0000 or 1111. There is important sequencing information about the initial set up. Which device to turn on first? If you get the pairing wrong you may end up locking yourself out of the device and having to uninstall the software and reinstall it. Take your time and do it right the first time. Check Device Manager for problems before you attempt any connections to Windows machines.

GPS not functioning

Let’s say for each life Bluetooth has saved, a fender bender was caused by a driver stating at a GPS. There are no facts to support this, it’s an opinion. GPS (Global Positioning System) uses satellites in geostationary or geosynchronous orbits around the earth to calculate locations on the planet. There are over 30 satellites orbiting the Earth transmitting time signatures of the highest accuracy. The GPS module can be attached to a laptop or housed in your smartphone. The GPS signal is low power and does not tolerate interference it also needs an unobstructed view of the sky. In order to accurately find its position on Earth the GPS module must be able to “see” 4 satellites. It then uses the precise time signatures from those satellites using the differences in reception to locate its position. The biggest problems with this system are obstruction of the sky and RF interference.

Touchscreen non-responsive

A non-responsive touch screen can have a variety of causes, to get back in First if you have a screen protector, remove it. Now turn the device off. Then clean the screen and your hands thoroughly. Don’t reinstall the screen protector until it can be ruled out as a problem, Restart the device and recalibrate the screen.

Apps not loading

If you have a condition where apps will not load or load slowly, the first thing to check is the battery. Is it overheating? Is the device warm to the touch? Very importantly examine the battery carefully for signs of swelling, which is a dangerous condition. Remove the battery and allow it to cool to room temperature. If the battery is swollen replace it immediately. Do not take chances with a swollen battery. If it is not swollen reinstall the battery and re-evaluate the condition.

Slow performance

Extremely short battery life and overheating – This condition is related to heat and also having too many apps open. Start your evaluation by feeling the temperature of the device in areas not related to the battery. Consult your documentation for specific heat related remedies. This could be a combination of too many apps exhausting your resources and generating unwanted heat. Shut the device down and let it cool. Restart it and use your application manager to see exactly what gets loaded at startup. Make adjustments to the apps for resource usage and monitor the device for a recurrence of the heat issue. And if the steps above don’t work, you can always refresh the device back to its factory settings using the key combination from the manufacturer.

Unable to decrypt email

Most problems of this type are caused by a corrupted public key. You create your public key and share it with people you need to receive encrypted email from. If you can’t decrypt email at all the focus of the problem would be on your machine. It appears your public key is corrupt. You should recreate your public key and share it with your confidential contacts.

Frozen system

When we discuss a “Frozen” system we are usually talking about a smartphone or tablet. A system lockup or freeze cannot be recovered. Your only option is to do a soft reboot. Each manufacturer has a different method for rebooting from a lockup. Follow the manufacturer’s instructions for doing this.

No sound from speakers

Sound issues on a mobile device could be either hardware or software based so we have to check everything, its less work you check the software first. The user may have turned down the volume or muted the speakers, Check the Sound device in Device Manager see it has problems, Check the drivers and update them.

If all the above fail try the Hardware Troubleshooter in Control Panel. If these methods fail, try a set of headphones or external speakers. If they don’t work you may have a hardware problem.

Disassembling processes for proper re-assembly

Disassembling a laptop can be one of your greatest challenges unless you adhere to several simple steps. First and foremost: Don’t even touch the laptop unless you have the proper documentation from the manufacturer and always wear a ground strap. Then Remove all power sources from the unit. This includes the battery and AC adapter

Document and label cable and screw locations

Take pictures if you can.

Organize parts

There are several ways to organize the removed parts. You can take notes and tape the screws to the paper. You can use the repair manual and tape the screws next to the appropriate instructions. Or label the removed parts and use an empty egg carton or pill box to keep them together. This reduces the possibility of an accident.

Refer to manufacturer resources

Always check the diagrams or pictures in the repair manual follow them to the letter.

Use appropriate hand tools

Inside a laptop you will find different screw sizes, lengths and screw head configurations. You’ll see different size Phillip’s heads, flat heads and differently sized Torx heads. Your repair manual will have these clearly labeled. Use the right tool for the job or damage may result.

Back to the main 901 ExamNotes page

That’s it for 4.5. Only one Sub-Objective left to go for A+ 220-901 and (If you read them all) you are that much closer to success. Good Luck on the test!

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