Troubleshooting Flashcards
How to Troubleshoot steps
Identify the problem
Establish a theory
Test the theory
Create a plan of action
Implement the solution
Verify full system functionality
Document findings
Common Hardware Problems – POST (Power On Self Test)
- Test major system components before booting
the operating system
– Main systems (CPU, CMOS, etc.)
– Video
– Memory - Failures are usually noted with beeps and/or codes
– BIOS versions can differ, check your documentation - Don’t bother memorizing the beep codes
– They’re all different between manufacturers
– Know what to do when you hear them
Common Hardware Problems – POST and boot
- Blank screen on boot
– Listen for beeps
– Bad video, bad RAM, bad CPU
– BIOS configuration issue - BIOS time and setting
– Maintained with the motherboard battery
– Replace the battery - Attempts to boot to incorrect device
– Set boot order in BIOS configuration
– Confirm that the startup device has
a valid operating system
– Check for media in a startup device
Common Hardware Problems – Crash screens
Windows Stop Error or Blue Screen of Death
* Contains important information
– Also written to event log
* Useful when tracking down problems
– Sometimes more useful for manufacturer support
Common Hardware Problems – Bluescreens and spontaneous shutdowns
- Startup and shutdown BSOD
– Bad hardware, bad drivers, bad application - Use Last Known Good, System Restore, or Rollback Driver
– Try Safe Mode - Reseat or remove the hardware - If possible
- Run hardware diagnostics
– Provided by the manufacturer
– BIOS may have hardware diagnostics
Common Hardware Problems – The spinning ball of death
- The macOS X Spinning Wait Cursor
– Feedback that something is happening - The spin starts, but it never stops
– You never get back control of your computer - Many possible reasons
– Application bug
– Bad hardware
– Slow paging to disk - Restart the computer
– There may be details in the console logs
Common Hardware Problems –Black screen
- Is the monitor connected?
– We wouldn’t ask if it wasn’t a common solution
– Check both power and signal cable - Input selection on monitor - HDMI, DVI, VGA, etc.
- Image is dim - Check brightness controls
- Swap the monitor
– Try the monitor on another computer - No video after Windows loads
– Use VGA mode (F8)
Common Hardware Problems –No power
- No power
– No power at the source
– No power from the power supply
– Get out your multimeter - Fans spin - no power to other devices
– Where is your fan power connected?
– No POST - bad motherboard?
– Case fans have lower voltage requirements
– Check the power supply output
Common Hardware Problems –Sluggish performance
- Task Manager
– Check for high CPU utilization and I/O - Windows Update
– Latest patches and drivers - Disk space
– Check for available space and defrag - Laptops may be using power-saving mode
– Throttles the CPU - Anti-virus and anti-malware
– Scan for bad guys
Common Hardware Problems –Overheating
- Heat generation
– CPUs, video adapters, memory - Cooling systems
– Fans and airflow
– Heat sinks
– Clean and clear - Verify with monitoring software
– Built into the BIOS
– Try HWMonitor
– http://www.cpuid.com/
Common Hardware Problems –Smoke and burning smell
- Electrical problems
– The smoke makes everything work - Always disconnect power
– There should never be a burned odor - Locate bad components
– Even after the system has cooled down
– Replace all damaged components
Common Hardware Problems –Intermittent shutdown
No warning, black screen
– May have some details in your Event Viewer
* Heat-related issue
– High CPU or graphics, gaming
– Check all fans and heat sinks
– BIOS may show fan status and temperatures
* Failing hardware
– Has anything changed?
– Check Device Manager, run diagnostics
* Could be anything
– Eliminate what’s working
Common Hardware Problems –Application crashes
- Application stops working
– May provide an error message
– May just disappear - Check the Event Log
– Often includes useful reconnaissance - Check the Reliability Monitor
– A history of application problems
– Checks for resolutions - Reinstall the application
– Contact application support
Common Hardware Problems –Grinding noises
- Computers should hum, not grind
- Rattling - Loose components
- Scraping - Hard drive issues
- Clicking - Fan problems
- Pop - Blown capacitor
Common Hardware Problems –Lockups
- System completely stops
– Completely. Usually not much in the event log
– Similar to unexpected shutdowns - Check for any activity
– Hard drive, status lights, try Ctrl-Alt-Del - Update drivers and software patches
– Has this been done recently? - Low resources - RAM, storage
- Hardware diagnostics may be helpful
Common Hardware Problems –Continuous reboots
- How far does the boot go before rebooting?
– BIOS only? OS splash screen? - Bad driver or configuration
– F8, “Boot from last known working configuration” - Try F8, Safe Mode
– If system starts, disable automatic restarts
in System Properties - Bad hardware
– Try removing or replacing devices
– Check connections and reseat
Common Hardware Problems –Inaccurate system date/time
- Bad motherboard battery
– Often a “button” style battery - A bad battery will require a BIOS configuration or
date/time configuration on every boot - On older systems, can reset the BIOS configuration
by removing the battery
– Newer computers use a jumper
Common Storage Devices Problems –Storage failure symptoms
- Read/write failure
– “Cannot read from the source disk” - Slow performance
– Constant LED activity - Retry…retry…retry - Loud clicking noise
– The click of death
– May also include grinding and scraping
Common Storage Devices Problems –Troubleshooting disk failures
- Get a backup - First thing - a bad drive is bad
- Check for loose or damaged cables
- Check for overheating
– Especially if problems occur after startup - Check power supply
– Especially if new devices were added - Run hard drive diagnostics
– From the drive or computer manufacturer
– Preferably on a known-good computer
Common Storage Devices Problems –Boot failure symptoms
- Drive not recognized, Boot Device Not Found
– Lights (or no lights)
– Beeps
– Error messages - Operating system not found
– The drive is there
– Windows is not
Common Storage Devices Problems –Troubleshooting boot failures
- Check your cables
– Physical problem - Check boot sequence in BIOS
– Check for removable disks (especially USB)
– Check for disabled storage interfaces - For new installation, check hardware configuration
– Data and power cables
– Try different SATA interfaces - Try the drive in a different computer
Common Storage Devices Problems –Data loss/corruption
- Hard drives are mechanical devices
– They will eventually fail - Repairs are difficult and expensive
– Dust-free environment
– Not always successful - An SSD may simply stop working
– Sometimes can read but not write - Data becomes unavailable or corrupted
– Can be impossible to recover - ALWAYS HAVE A BACKUP
Common Storage Devices Problems –RAID not found
- Missing or faulty RAID controller
Common Storage Devices Problems –RAID stops working
- Each RAID is different
– Don’t start pulling drives until you check the console!
Common Storage Devices Problems –S.M.A.R.T.
- Self-Monitoring, Analysis, and Reporting Technology
– Use third-party utilities - Avoid hardware failure - Look for warning signs
- Schedule disk checks - Built-in to most drive arrays
- Warning signs - Replace a drive
Common Storage Devices Problems –Extended read/write times
- A lot happens when reading or writing data
– Memory access, communication across the bus,
spinning drive access, writing or reading the data to
the storage device, etc. - Delays can occur anywhere along the way
– Need a way to measure storage device access - Input/output operations per second (IOPS)
– A broad metric of maximum performance - Useful for comparing storage devices
– Hard drive: 200 IOPS
– SSD: 1,000,000 IOPS
Common Storage Devices Problems –Missing drives in OS
- OS boots normally
– Other drives not shown - Check the BIOS - Internal drives
– Bad drive or disconnected cable - External drives
– No power to the drive or bad cable connection - Network shares
– Shared drives can be connected during startup
– Option to reconnect at sign-in
– Connected with login script
Troubleshooting Video and Display Issues – No video image
- Is it connected?
– We wouldn’t ask if it wasn’t a real solution
– Check both power and signal cable - Input selection on monitor
– HDMI, DVI, VGA, etc. - Image is dim
– Check brightness controls - Swap the monitor
– Try the monitor on another computer - No video after Windows loads
– Use VGA mode (F8)
Troubleshooting Video and Display Issues – Image quality problems
- Flickering, color patterns incorrect
– You can almost work with this - Check the cable pins
– Especially if missing a color - Distorted image and geometry
– Check the OS refresh rate and resolution settings
– Need to match the display specifications
– Check or replace cable - Disable hardware acceleration
– Troubleshoot with the software drivers
Troubleshooting Video and Display Issues – Native resolution
- An LCD display is fixed
– The number of pixels doesn’t change - A display looks best when the video settings match
a display’s native resolution
– A mismatch can cause distortion - If changing the display resolution,try using a multiple
of the native resolution
– 2560 x 1600 is the same ratio as 1920 x 1200
Troubleshooting Video and Display Issues – Burn-in
- A problem across all monitor types
– Some displays will pixel-shift
– You probably won’t notice it - LCDs have “image sticking”
– Try to remove by displaying a white screen for an
extended period
Troubleshooting Video and Display Issues – Dead pixels
- Always black
– A manufacturing defect - This probably isn’t a problem on your side
– Not a cable or power issue - Clean the monitor screen
– Damp cloth - You’ll have to replace the monitor
– No other option
Troubleshooting Video and Display Issues – Flashing screen
Check the video cable connections
– A loose cable will cause loss of signal
* Replace the video cable
– Usually a quick fix
* The problem could be with the monitor
– Try switching the display
* Confirm the display settings in the operating system
– May not match the monitor
Troubleshooting Video and Display Issues – Incorrect color display
- Colors may not be properly represented
– Too much red, green, blue, yellow, etc. - Monitor settings
– Tint
– Custom color presets
– Factory Reset - Driver configuration
– Color tint - OS configuration - Very blue
– Night light settings
Troubleshooting Video and Display Issues – Audio issues
- Many monitors include speakers
– No sound, low volume - Monitor may have audio controls
– Check volume levels and mute status - Confirm audio input over HDMI, DisplayPort, or
Thunderbolt
– Check the HDMI audio output in the OS - The monitor may support other audio input interfaces
– Check for audio jacks
Troubleshooting Video and Display Issues – Dim image
- Monitor video settings
– Brightness
– Contrast - Check the OS
– Auto-dimming
– Dim on battery power
– Driver settings - Backlight failure
– Some or all of the light
– May only be a section of the screen
Troubleshooting Video and Display Issues – LCD projector troubleshooting
- Large screen projection
– Conference rooms, large gatherings - Not always LCD
– But common to see LCD - Metal-halide lamp
– Very bright (very hot) light
– Relatively expensive
– (~ $35 to $350+ US) - Always let bulbs cool
– Fan will run after shutting off
– Keep it plugged in - Intermittent projector shutdown
– No light output
– Fans may continue to run - Cooling issue
– Fans constantly cool the bulb
– Shuts down if temperatures are high - Check the airflow
– Remove any blockages
– Clean dust from the air filters and external
air input/output
Troubleshooting Mobile Devices – Poor battery health
- Replace aging battery
– There’s only so many recharges - Bad reception
– Always searching for signal
– Airplane mode on the ground - Disable unnecessary features
– 802.11 wireless, Bluetooth, GPS - Check application battery usage
– iOS and iPadOS: Settings/Battery
– Android: Settings/Battery
Troubleshooting Mobile Devices – Swollen battery
Buildup of gas
– Designed to self-contain
– Do NOT open the battery packet/container
– Significant fire risk
– You’ll be sorry
* Faulty battery
– Stop using immediately
– Dispose of properly
* Device can be damaged
– Better than having a fire
Troubleshooting Mobile Devices – Broken screen
- Time for a backup - Do this first!
- Replace the screen - No easy fixes
- The glass is sharp
– Screen protectors can help
– Use clear tape until repaired
Troubleshooting Mobile Devices – Improper charging
- Check everything in the charging process
– Cables, interfaces - Check the cable interface
– Remove any obstructions - Check the cable
– Don’t use frayed or damaged cables
– Try a known-good cable - Verify the power adapter
– Check with a multimeter
Troubleshooting Mobile Devices – Poor or no connectivity
Cellular or Wi-Fi
– Location, location, location
* Cellular
– Signal strength
– Location matters
– Outdoor connectivity may be better
* Wi-Fi
– Limited range
– Interference can limit throughput
– May need a channel/frequency configuration change
Troubleshooting Mobile Devices –Liquid damage
Many phones have a Liquid Contact Indicator (LCI)
– Turns color when liquid has been present
* Power down the phone
– Don’t power it back on. Don’t do it.
* Remove the case, cards, back, and battery
– If possible
* Putting the phone in a bag of rice doesn’t
actually work very well
– Silica gel is better
* Leave it alone
– Don’t turn it on
– Do not charge the phone
– Don’t connect it to power
– Don’t press any keys
– Don’t heat the phone
– Don’t move it around
* Wait at least a day
– Or until the phone appears to be dry
– And then perhaps a few hours after that
* Once you’re sure, power it on
– Hope for the best
Troubleshooting Mobile Devices –Overheating
- Phone will automatically shut down
– Avoid overheating damage - Charging/discharging the battery, CPU usage,
display light
– All of these create heat - Check app usage
– Some apps can use a lot of CPU - Avoid direct sunlight
– Quickly overheats
Troubleshooting Mobile Devices –Digitizer issues
- Touchscreen completely black or
not responding to input
– Screen presses do not register - Apple iOS reset
– Press power button, slide to power off,
press power button
– Hold down power button and Home|Volume
for 10 seconds - Android device restart
– Remove battery, put back in, power on
– Hold down power and volume down until restart
– Some phones have different key combinations
– Some phones do not have a key-based reset
Troubleshooting Mobile Devices –Physically damaged ports
- External interface - Charging and data transfer
- Rough handling and accidents
– Damages the interface - Not charging - Look closely
- Not modular - Requires a system board replacement
Troubleshooting Mobile Devices –Malware
- Always a concern
– Even on mobile devices
– The device type doesn’t matter - Look for symptoms
– Unusual apps, large data transfers, pop up messages,
high CPU usage, device overheating, excessive
battery use
Troubleshooting Mobile Devices –Cursor drift
- Random input or cursor moves without
touching the device
– Common on older screens - Use a touch calibration app
– Requires user input
– Touch certain areas of the screen - The system will adjust to the new calibration parameters
– No more drif
Troubleshooting Networks – No network connectivity
Do you have a link light?
– Is it plugged in?
* Ping loopback (127.0.0.1)
– Is the protocol stack working?
– Availability and intermittent connectivity
* Ping local IP address
– Checks local configuration, adapter, and link signal
* Ping default gateway
– Connectivity on the local network
* Ping devices on router’s other side
– 8.8.8.8 or 9.9.9.9
Troubleshooting Networks – Intermittent wireless connectivity
- Interference
– Something else is using our frequency - Signal strength
– Transmitting signal, transmitting antenna,
receiving antenna, etc. - Incorrect channel
– Usually automatic; look for manual tuning - Bounce and latency
– Multipath interference; flat surfaces - Incorrect access point placement
– Locate close to the users
Troubleshooting Networks – Wireless interference
- Predictable
– Fluorescent lights
– Microwave ovens
– Cordless telephones
– High-power sources - Unpredictable
– Multi-tenant building - Measurements
– Signal to noise ratio (SNR)
– Performance Monitor
Troubleshooting Networks – Signal to noise ratio (SNR)
- Signal
– What you want - Noise
– What you don’t want
– Interference from other networks and devices - You want a very large ratio
– The same amount of signal to noise (1:1)
would be bad
Troubleshooting Networks – Limited or no connectivity
- Windows alert in the system tray
– “Limited or No connectivity”
– “No Internet Access” - Check the local IP address
– An APIPA address will only have local connectivity - If DHCP address is obtained,perform the ping tests
– Local gateway, remote IP address
Troubleshooting Networks – Jitter
- Most real-time media is sensitive to delay
– Data should arrive at regular intervals
– Voice communication, live video - If you miss a packet, there’s no retransmission
– There’s no time to “rewind” your phone call - Jitter is the time between frames
– Excessive jitter can cause you to miss information,
“choppy” voice calls
Troubleshooting Networks – Poor VoIP quality
- High speed and low latency
– Real-time applications are demanding - Check the Internet connection
– A speed test can identify slow links - Verify the local networking equipment
– An old router can cause significant problems - View the network performance
– A packet capture would be usefu
Troubleshooting Networks – Latency
- A delay between the request and the response
– Waiting time - Some latency is expected and normal
– Laws of physics apply - Examine the response times at every step along the way
– This may require multiple measurement tools - Packet captures can provide detailed analysis
– Microsecond granularity
– Get captures from both sides
Troubleshooting Networks – Port flapping
Network interface goes up and down
– Over and over again
* Verify the cable
– Check the wiring
* Move between switch interfaces
– Is the flapping associated with the switch
interface or the device?
* Replace bad hardware or cables
– May require additional purchases
