Chapter 12: Hardware and Network Troubleshooting

A+ Core 1 — 220-1101 | Objectives 2.8, 5.3 – 5.7

Chapter 12:
Hardware & Network Troubleshooting

Storage, video, mobile devices, printers, and network connectivity. This chapter covers more exam objectives than any other — symptom recognition and component mapping are the core skills.

22 Slides Objectives 2.8, 5.3–5.7 Storage • Display • Mobile • Printers • Network Exam 220-1101

Slide 2 of 22

Networking Tools

Objective 2.8: physical tools for cable installation, testing, and signal tracing.

Crimper

Attaches RJ-45 connectors to Ethernet cables. Essential for making custom-length patch cables and terminating network drops. Requires correct wire order (T568A or T568B) before crimping.

Cable Stripper

Removes the outer jacket from cables without cutting internal pairs. Used before crimping or punch-down termination. Improper stripping depth is a common cause of failed cable certification.

Wi-Fi Analyzer

Detects wireless networks, measures signal strength (RSSI), identifies channel overlap and interference sources. Can be hardware-based or software on a mobile device. Used to select optimal AP channel and placement.

Tone Generator & Probe

Traces cables through walls and ceilings. Generator sends an audible tone on the known end; the probe (wand) detects the tone to identify the other end. Also called "fox and hound" or "toner." Exam favorite for cable tracing scenarios.

Punchdown Tool

Inserts conductors into 110-block patch panels and 66-block cross-connects. Spring-loaded mechanism cuts excess wire simultaneously. Used for structured cabling termination in wiring closets and wall jacks.

Cable Tester & Loopback Plug

Cable tester: verifies continuity, identifies opens, shorts, and miswires pin-by-pin. Loopback plug: connects TX to RX pins — if a ping to the loopback succeeds, the NIC is functioning and the problem is external to the adapter.

Slide 3 of 22

Network Tap & Advanced Tools

Tools for packet capture, certification testing, and throughput measurement.

Network Tap

A passive inline device that copies network traffic without interrupting the live connection. Used for packet capture (Wireshark), security monitoring, and performance analysis. Unlike a SPAN port, a tap is hardware-based and captures all traffic including errors. Requires two capture ports (one per direction) on a full-duplex link.

Cable Certifier

High-end tool that certifies cable against TIA/EIA standards (Cat5e, Cat6, Cat6A). Tests parameters including attenuation, near-end crosstalk (NEXT), return loss, and propagation delay. Produces a pass/fail certification report. Required for warranty validation on structured cabling installations. Much more capable than a basic continuity tester.

Exam Tip

Know the distinction: a cable tester checks continuity and wiring order (pass/fail for basic connectivity); a cable certifier validates full performance parameters against a standard (required for Cat5e/6/6A certification). The tone generator finds a cable; the cable tester verifies it works; the certifier proves it meets spec.

A new office has 48 drops installed by a cabling contractor. Before accepting the work, a cable certifier is used on every drop. Three drops fail attenuation tests due to excessive untwisting at the punch-down terminations. The contractor re-terminates those drops at no charge because the certification report is contractual evidence of the failure.

Slide 4 of 22

Storage Troubleshooting

Objective 5.3: recognizing storage failure symptoms and mapping them to the correct response.

Symptom	Probable Cause	Correct Action
Grinding / clicking noises	HDD read/write head or motor failure	Back up immediately; replace drive; do not defrag
S.M.A.R.T. failure warning	Drive predicting imminent failure	Replace drive now; restore from backup
Bootable device not found	Boot order, loose cable, dead drive	Check BIOS boot order; reseat data cable
Extended read/write times	Fragmentation (HDD), drive degradation	Defrag HDD (not SSD); check S.M.A.R.T. status
Data loss / corruption	Bad sectors, malware, file system error	Run CHKDSK; verify S.M.A.R.T.; scan for malware
Drive missing in OS	Driver, cable, BIOS detection	Check BIOS, reseat cables, update drivers
LED indicators solid/flashing	Activity indicator or error code	Check manufacturer documentation for LED meaning

Critical

Grinding or clicking from an HDD means mechanical failure is in progress. Do NOT run defragmentation — this forces additional read/write operations that accelerate failure. Back up all accessible data by the most direct method available, then replace the drive.

Slide 5 of 22

S.M.A.R.T. and IOPS

Self-monitoring technology and the performance metric that quantifies storage throughput.

S.M.A.R.T.

Self-Monitoring, Analysis, and Reporting Technology. Built into all modern HDDs and SSDs since approximately 2004. Monitors drive health metrics including read error rate, reallocated sector count, spin-up time, uncorrectable sector count, and temperature. No universal standard — attribute meanings vary by manufacturer. Tools: CrystalDiskInfo, HD Tune, SpeedFan, GSmartControl. A yellow (caution) or red (bad) status means replace the drive regardless of current functionality.

IOPS

Input/Output Operations Per Second. Measures how many discrete read or write operations a storage device completes per second. HDDs typically deliver 100–200 IOPS. SSDs deliver tens of thousands to hundreds of thousands of IOPS. IOPS is the critical metric for RAID arrays, NAS devices, and server storage — not just sequential read/write throughput. Low IOPS causes application latency even when throughput appears adequate.

RAID Troubleshooting

RAID-specific failures in addition to standard drive problems: controller failure vs. individual drive failure — isolate which component failed before replacing both. Degraded array: one drive failed in a redundant set (RAID 1, 5, or 10); array still functions but has no fault tolerance until rebuilt. Rebuild time can be hours to days with significant performance impact. RAID is not a backup.

Boot Repair Commands

When a drive is present but the OS cannot be found, the MBR or boot sector may be corrupt. From Windows Recovery Environment: bootrec /fixmbr rewrites the Master Boot Record; bootrec /fixboot rewrites the boot sector; bootrec /rebuildbcd scans for installations and rebuilds the Boot Configuration Data store.

Slide 6 of 22

Display & Video Troubleshooting

Objective 5.4: two categories — No Video (nothing shows) vs. Bad Video (image quality problems).

Symptom	Probable Cause	Resolution
No image on screen	Monitor off, cable loose, video card failure	Check power and cable; test with different monitor
Dead pixels	Manufacturing defect or physical damage	Set background to white to identify count; replace monitor
Burn-in / ghosting	Static image displayed too long (OLED/plasma)	Use screen saver; replace if permanent
Dim or flickering image	Failing backlight (LED/CCFL) or inverter	Replace backlight assembly or monitor
Incorrect colors	Loose/damaged cable, bent pins, failing panel	Reseat cable; test different cable; replace monitor
Fuzzy/blurry image	Wrong resolution, analog interference, bad cable	Set native resolution; use digital (HDMI/DP) connection
Overheat shutdown	Blocked vents, dust, GPU fan failure	Clean vents; check GPU fan; improve case airflow
Distorted geometry	Wrong aspect ratio or scaling	Match resolution to monitor's native spec

Exam Tip

Always check the input source first. Many display calls are resolved by pressing the monitor's Input/Source button. Also verify brightness is not at minimum. These are the simplest explanations and the exam expects you to eliminate them first.

Slide 7 of 22

Projector-Specific Issues

Projectors have unique failure modes beyond standard monitor problems.

Burned-Out Bulb

Projector lamps have a finite lifespan: typically 2,000–5,000 hours depending on bulb type. Most projectors display a warning when lamp hours approach the end of rated life. Symptoms: sudden darkness, flickering at startup, or dim image that worsens over time. Replace with the manufacturer-specified lamp, not a generic substitute.

Intermittent Shutdown

Almost always a thermal issue. Projectors generate substantial heat and require clean air filters and unobstructed vents. If the projector shuts off mid-presentation after running for a while, check and clean air filters. Ensure adequate ventilation clearance around the unit. A failed internal fan will also cause thermal shutdown quickly after startup.

Fuzzy or Misaligned Image

First adjust the focus ring on the lens. Verify throw distance matches the lens specifications. Check that the input source resolution matches the projector's native resolution. Clean the lens with a lens cloth — dust or fingerprints create soft, degraded images. Keystone correction adjusts for non-perpendicular projection angles.

No Image from Projector

Check the input source selection on the projector itself. Verify the laptop is outputting to an external display (typically Fn + a display key). Confirm the cable is seated at both ends. If the projector shows a "no signal" OSD, the hardware connection is the problem. If no OSD appears at all, the projector may not be powering on correctly.

Slide 8 of 22

Mobile Devices: Power & Battery

Objective 5.5: battery issues are the most safety-critical mobile troubleshooting category.

Poor Battery Health

Battery capacity degrades with charge cycles. A battery that originally lasted 10 hours lasting only 4 hours after 2 years is normal degradation, not a defect. Check battery health percentage in device settings. iOS: Settings → Battery → Battery Health. Android: manufacturer diagnostic apps vary. At 80% or below, replacement is recommended for heavy users.

Swollen Battery

A swollen or puffed lithium-polymer battery is undergoing chemical decomposition and is a fire and explosion hazard. Symptoms: case bulging, screen separating from the frame, or the device visibly thicker than normal. Stop using the device immediately. Do not charge it. Do not compress or puncture the battery. Deliver to an electronics recycling facility. Continued use risks fire.

Improper Charging

Use the OEM charger and cable where possible. Third-party chargers that do not correctly negotiate charging profiles can damage the battery over time. Inspect the charging port for debris (especially USB-C and Lightning ports), which is a common cause of "not charging" symptoms. A can of compressed air or a wooden toothpick clears most port debris safely.

Overheating

Mobile device overheating causes: runaway background process consuming CPU; direct sunlight or hot environment; battery nearing end of life; background app or malware. Remediation: close all apps and restart. If persistent, check which app is consuming CPU in settings. Identify and remove rogue apps. Move device to a cooler location. Factory reset as last resort.

Slide 9 of 22

Mobile Devices: Display & Connectivity

Physical and software causes of screen, touch, and wireless failures.

Broken Screen / Digitizer

The LCD displays the image; the digitizer detects touch. Both can fail independently. A cracked digitizer that still displays an image may lose touch accuracy (cursor drift) or responsiveness in specific areas. Screen assembly replacement includes both layers. Always test touch calibration after installation. Third-party screen protectors can interfere with digitizer sensitivity.

Wireless Connectivity

No Wi-Fi: check that Wi-Fi is toggled on and airplane mode is off. Verify the network exists and the password is correct. Forget and rejoin the network. Check for router issues by testing with another device. Bluetooth pairing fails: unpair both devices and re-pair. Check for interference from 2.4 GHz devices. A persistent Wi-Fi issue on one device may indicate a hardware Wi-Fi module failure.

Liquid Damage

Do not charge a liquid-damaged device — applying power to wet components causes short circuits and accelerates corrosion. Power off immediately. Remove case and SIM card. Place in a container with silica gel packets for 48 hours minimum (rice is ineffective). Professional ultrasonic cleaning and inspection is the correct repair path. Data recovery may be possible even if the device does not revive.

1

Slow performance or frozen screen: force restart (hold power + volume down typically). Clear app cache. Check available storage — at least 10% free space is needed for normal operation.

2

Persistent issues unresolvable by software: factory reset after backing up data. This eliminates all software as a cause and confirms or rules out hardware.

Slide 10 of 22

Impact Printer Problems

Objective 5.6: dot matrix and impact printers have specific failure modes tied to mechanical components.

Symptom	Cause	Solution
Faded / light characters	Worn ribbon	Adjust print head closer to platen; replace ribbon
Print goes from dark to light	Ribbon-advance gear slipping	Replace ribbon-advance mechanism
Consistent blank line across page	Print head pin permanently stuck in	Replace print head
Intermittent blank line	Loose print head cable	Secure or replace the cable
Garbled characters	Wrong driver, bad interface cable, PCB failure	Verify driver; replace cable; replace interface board
Unevenly spaced lines	Stepper motor problem	Replace stepper motor

Context

Impact printers are still encountered in environments requiring multi-part forms (carbon copies): shipping docks, auto repair shops, medical records, and point-of-sale systems where a physical impression through multiple layers is required. No other technology can print through carbon paper; this is the sole remaining use case for impact technology.

Slide 11 of 22

Inkjet Printer Problems

Most inkjet problems trace back to the ink cartridge. Replace the cartridge first.

Thin Blank Lines in Print

Plugged or clogged nozzle in the cartridge. Run the print head cleaning utility from the printer software or control panel. This forces ink through the nozzles to clear blockages. Run twice if the first pass does not fully clear. If cleaning fails after multiple attempts, replace the cartridge. Cartridges left unused for extended periods dry out and clog.

Faded or Light Output

Cartridge is low on ink or nozzles are partially blocked. Replace the cartridge if the ink level is low. If the cartridge is not empty, run the head cleaning utility. Verify that photo-quality paper is being used for photo printing — plain paper produces visibly lighter results from the same cartridge.

Color Bleeding / Wrong Colors

Color bleeding: using wrong paper type (plain paper absorbs more ink) or a cartridge with a micro-leak. Use the paper type specified for the printer. Wrong colors: cartridges installed in incorrect slots. Remove all cartridges and reinstall each in its labeled slot. Run the alignment utility after reinstallation.

Too Much Ink / Smearing

A hole or crack in the cartridge floods the paper. Replace the cartridge immediately. Excess ink can contaminate the print head assembly if the cartridge continues to run. Inspect the print head for ink pooling after replacing a leaking cartridge.

Multiple Sheets Feed

Bad or worn separator pad rollers, or sticky / damp paper. Replace separator pads if worn. Fan the paper stack before loading to separate sheets. Use dry, properly stored paper. High humidity environments cause paper to stick together and misalign.

Slide 12 of 22

Laser Printer Problems

Laser symptoms map directly to the 7-step imaging process: Processing → Charging → Exposing → Developing → Transferring → Fusing → Cleaning.

Symptom	Failing Component / Step
Blank pages output	Empty toner, failed transfer corona, high-voltage power supply (HVPS)
All-black pages	Primary corona wire failure — drum not receiving initial charge
Vertical white lines (streaks)	Dirty corona wire or scratched drum surface
Vertical black lines	Groove or deep scratch in the EP drum
Toner smears / rubs off	Fuser not reaching correct temperature (~350°F / 177°C)
Ghosting (faint repeated image)	Toner cartridge — drum not cleaning properly (Cleaning step)
Repetitive spots or marks	Toner spill or cracked/chipped drum surface
Pages of garbage text	Wrong printer driver or formatter board failure
Paper jams	Worn pickup rollers, incorrect paper type, overfilled tray

Exam Strategy

Match the symptom to the imaging step that failed. Smearing = fuser. All-black = primary corona. Blank = transfer corona or HVPS. Ghosting = cleaning blade. Vertical lines = dirty corona or drum scratch. This mapping is exam-tested in scenario format.

Slide 13 of 22

Print Queue & Spooler Management

Print jobs stuck in the queue require a specific resolution sequence on Windows.

Print Spooler Service

The Windows Print Spooler service (spoolsv.exe) manages all print jobs. A stuck or corrupted job in the queue can prevent any new jobs from printing. Symptoms: jobs appear in the queue but the printer does nothing, even after a printer reboot. The queue cannot be cleared normally because the spooler holds file locks on the spool files.

Clear Stuck Queue

Stop the Print Spooler service (services.msc or net stop spooler). Navigate to C:\Windows\System32\spool\PRINTERS and delete all files in this directory (not the directory itself). Restart the Print Spooler service (net start spooler). The queue is now empty and new jobs can be sent. This resolves the majority of stuck queue issues.

1

Print a test page first (Printer Properties → Print Test Page). If the test page prints, the hardware is functional and the problem is software-side: driver, queue, or application.

2

Check error codes on the printer display. Most modern printers show specific error codes. Look up the code in the manufacturer documentation for directed troubleshooting.

3

Update or reinstall the driver if output is garbled or the printer is misidentified. Always use the manufacturer's driver, not a generic or Windows-provided driver, for full feature support.

4

For network printers: verify the IP address is correct, ping the printer from the workstation, and check that port 9100 (JetDirect/RAW printing) or port 631 (IPP) is not blocked by firewall.

Slide 14 of 22

Network Connectivity Symptoms

Objective 5.7: map each symptom to probable cause and first diagnostic step.

Symptom	Probable Cause	First Step
No connectivity	Physical cable, NIC, switch port, IP config	Check physical connection; run ipconfig
SSID not found	AP off or out of range, Wi-Fi disabled, interference	Verify AP is operational; check Wi-Fi toggle
Limited connectivity	No default gateway or DNS; DHCP partial failure	Check gateway and DNS in ipconfig /all
APIPA (169.254.x.x)	DHCP server unreachable; client on wrong VLAN	Verify DHCP service is running; check VLAN assignment
IP address conflict	Duplicate static IP on network	Switch to DHCP or assign a unique static address
Intermittent drops	Bad cable, port flapping, interference (wireless)	Check switch logs; replace cable; test port

APIPA Indicator

An IP address of 169.254.x.x means the client failed to reach a DHCP server and auto-assigned a link-local address. This is always a symptom — not a configuration choice. First check: is the DHCP server running? Is the client in the correct VLAN? Is there a switch misconfiguration preventing DHCP discovery packets from reaching the server?

Slide 15 of 22

Network Performance Issues

Slow, intermittent, or degraded network performance has identifiable causes beyond "bad network."

High Latency

Measured in milliseconds via ping. Delay in packet delivery from source to destination. Causes: network congestion, excessive hops, routing inefficiency, or QoS misconfiguration. High latency devastates real-time applications (VoIP, video conferencing, online gaming) while having minimal impact on file transfers or email.

Jitter

Variation in packet arrival times. Example: packets arriving 10ms, 10ms, 40ms, 10ms, 85ms — the variation (jitter) destroys VoIP call quality even if average latency is acceptable. VoIP requires consistent latency, not just low latency. Resolve with QoS policies that prioritize voice traffic and buffer jitter at the endpoint.

Port Flapping

A switch port rapidly toggling between up and down states. Appears in switch logs as repeated link up/down events for the same port. Caused by: bad cable or connector, failing NIC, marginal SFP module, or a Spanning Tree Protocol (STP) topology issue. Replace the cable first; if it persists, swap the switch port.

Slow Network Speeds

Check for duplex mismatch: one side at full-duplex, other at half-duplex causes collisions and reduced throughput. Verify cable category is appropriate for the speed (Cat5e for GbE, Cat6A for 10GbE). Check for congestion and bandwidth contention. Ensure NIC is negotiating at the correct speed.

External Interference (Wireless)

2.4 GHz band interference from microwave ovens, cordless phones, and neighboring APs on overlapping channels (use 1, 6, or 11 for non-overlapping in 2.4 GHz). 5 GHz and 6 GHz bands have more non-overlapping channels and less device interference but shorter range. Wi-Fi analyzer identifies channel congestion and helps select the least occupied channel.

Slide 16 of 22

Network Command-Line Tools

Know each command, its function, and when to use it. These appear in A+ exam scenarios.

ipconfig / ifconfig

Windows: ipconfig. Linux/macOS: ifconfig or ip addr. Displays IP address, subnet mask, and default gateway. Use ipconfig /all for MAC address, DNS servers, DHCP server, and lease information. Use ipconfig /release then /renew to force DHCP re-assignment. First tool used in any network troubleshooting sequence.

ping

Tests ICMP echo connectivity to a host. Reports round-trip time and packet loss. ping 127.0.0.1 tests the local TCP/IP stack. ping [own IP] tests the NIC. ping [gateway] tests local connectivity. ping [internet IP] tests external routing. ping [hostname] tests DNS resolution. Each step isolates a layer of the network stack.

tracert / traceroute

Traces the path packets take to a destination, showing each hop (router) with latency. Windows: tracert. Linux: traceroute. Identifies where in the path a delay or failure occurs. A * * * response at a hop means that router does not respond to ICMP TTL-exceeded messages — it does not necessarily mean the hop is the problem.

pathping

Windows-only. Combines tracert and ping: traces the route then pings each hop repeatedly over a measurement period. Calculates packet loss percentage at each hop. More diagnostic than tracert for identifying congested or degraded links. Takes 2–5 minutes to complete (unlike the quick tracert response).

nslookup

Queries DNS servers for name resolution. nslookup google.com returns the IP address. Can specify an alternate DNS server: nslookup google.com 8.8.8.8. Confirms whether DNS resolution is the cause of connectivity issues when ping to IP works but ping to hostname fails.

netstat

Displays active TCP/IP connections, listening ports, and routing table. netstat -an shows all connections in numeric format. netstat -b shows the process associated with each connection. Used to identify unexpected listening ports, active connections to suspicious hosts, or confirm a service is actually listening on the expected port.

Slide 17 of 22

Ping Troubleshooting Sequence

Use ping in order from local to remote to isolate which layer of the network stack is failing.

1

ping 127.0.0.1 — loopback address. Tests whether TCP/IP is installed and functioning on the local machine. Failure here means TCP/IP stack corruption.

2

ping [own IP address] — tests the local NIC and its driver. If step 1 passed but step 2 fails, the NIC or its driver is the problem.

3

ping [default gateway IP] — tests the local network segment and the path to the router. Failure here indicates a local network problem: cable, switch port, VLAN, or router.

4

ping [remote IP address] (e.g., 8.8.8.8) — tests routing beyond the gateway to the internet. Failure here with step 3 passing indicates a routing or ISP problem.

5

ping [hostname] (e.g., google.com) — tests DNS resolution. If steps 1–4 pass but step 5 fails, the problem is DNS configuration. Verify DNS server addresses with ipconfig /all.

Exam Alert

This sequence is tested directly. "A user can ping 8.8.8.8 but cannot reach www.google.com. What is the likely cause?" — DNS failure. They have IP connectivity (step 4 passes) but hostname resolution (step 5) fails.

Slide 18 of 22

Wireless Troubleshooting

Wi-Fi issues layer physical signal problems on top of standard network stack problems.

No SSID Visible

If the AP is broadcasting (SSID not hidden): client is out of range, Wi-Fi adapter is disabled (check Fn key + Wi-Fi key on laptops, or Device Manager), or driver has crashed. If SSID is hidden: manually enter the network name, security type, and password. If the AP is suspected: ping its management IP from a wired client to verify it is powered and connected.

Connected But No Internet

Association to the AP succeeded but IP configuration failed (APIPA address) or default gateway is unreachable. Run ipconfig to confirm the IP address. If APIPA, the DHCP server is not responding. Try ipconfig /release and /renew. If a valid IP is assigned but internet fails, run the ping sequence to identify at which hop connectivity breaks.

Weak or Intermittent Signal

Distance, physical obstructions (concrete walls, elevator shafts, RF-shielded rooms), and co-channel interference all degrade signal. Use a Wi-Fi analyzer to measure RSSI at the client location. Signal below –70 dBm is marginal; below –80 dBm is unusable. Solutions: add an AP, move existing AP, switch to 5 GHz for less congested channels, or install a wireless repeater/mesh node.

Channel Overlap

In the 2.4 GHz band, only channels 1, 6, and 11 are non-overlapping. APs on adjacent channels create co-channel interference that degrades throughput. A Wi-Fi analyzer showing neighbors on channel 6 while your AP is also on channel 6 is a co-channel interference problem. Switch to channel 1 or 11. The 5 GHz band has 24+ non-overlapping channels in most regions.

Slide 19 of 22

Practice Scenarios

Apply Chapter 12 knowledge. Identify the correct diagnosis and action.

S1

A laser printer outputs pages where the toner easily rubs off with a finger. What component is at fault? — The fuser. It is not reaching the correct temperature (~350°F) to permanently bond toner to the paper.

S2

A user's workstation gets a 169.254.x.x address after connecting to the network. What should you check first? — DHCP server availability. The client could not reach DHCP and self-assigned an APIPA address. Verify DHCP service is running and the client is on the correct VLAN.

S3

An HDD produces clicking sounds intermittently. S.M.A.R.T. shows "Caution" status. The drive still mounts. What is the correct action? — Back up all data immediately and replace the drive. A clicking drive with S.M.A.R.T. warnings is in active failure. Do not wait for full failure.

S4

A user can ping 192.168.1.1 (gateway) but cannot reach www.microsoft.com. Pinging 13.107.4.52 (Microsoft's IP) succeeds. What is the problem? — DNS failure. IP connectivity is present (ping to IP works) but hostname resolution fails. Check DNS server settings via ipconfig /all.

S5

A mobile phone case is visibly bulging on the back panel. What is the correct action? — Stop using the device immediately. Do not charge it. The battery is swollen and is a fire hazard. Take to an electronics recycling facility.

Slide 20 of 22

More Exam Scenarios

Display, printer, and storage scenarios with correct answers.

S6

A laser printer produces all-black pages on every print job. What component has failed? — The primary corona wire (or primary charge roller). It is not applying the initial uniform negative charge to the EP drum, so toner adheres to the entire surface.

S7

A monitor displays a blue tint on all images. The cable was recently replaced. What should you check? — Inspect the video cable connection for bent pins (VGA) or a loose connector. A missing ground pin or loose HDMI/DP connector can cause color channel imbalance.

S8

A cable run fails certification due to excessive NEXT (Near-End Crosstalk). What is the most likely installation error? — The pairs were untwisted too far at the termination point (punchdown or crimp). The pair twist reduces crosstalk; untwisting more than 0.5 inch eliminates this protection.

S9

Print jobs are sent to a network printer but nothing prints, and the queue shows jobs stuck with "deleting" status. What is the fix? — Stop the Print Spooler service, delete all files in C:\Windows\System32\spool\PRINTERS, then restart the Print Spooler service.

Slide 21 of 22

Key Vocabulary

Chapter 12 terms organized by topic area.

Storage & Display

S.M.A.R.T. — drive self-monitoring and health reporting
IOPS — Input/Output Operations Per Second
RAID degraded — one drive failed, array still running without redundancy
Burn-in — persistent image retention on OLED/plasma
Dead pixel — permanently off or stuck-on pixel
Backlight — LED or CCFL illumination source behind LCD panel

Network & Wireless

APIPA — Automatic Private IP Addressing (169.254.x.x)
Jitter — variation in packet arrival latency
Port flapping — switch port cycling up/down rapidly
SSID — Service Set Identifier (Wi-Fi network name)
Co-channel interference — neighboring APs on same channel
QoS — Quality of Service; traffic prioritization policy

Printers & Mobile

Fuser — laser printer component that bonds toner with heat
Primary corona — charges the EP drum before laser exposure
Transfer corona — transfers toner from drum to paper
Print Spooler — Windows service managing print queues
Digitizer — touch-sensing layer on mobile displays
Separator pad — prevents multiple sheets feeding together

Slide 22 of 22 — Chapter 12 Complete

Chapter 12 Summary

Eight key takeaways from Hardware and Network Troubleshooting.

1

Storage: grinding or clicking from an HDD means imminent failure. Back up immediately. S.M.A.R.T. caution status = replace the drive now, even if it still functions.

2

Laser printer symptoms map to imaging steps. Smearing = fuser. All-black = primary corona. Blank page = transfer corona or HVPS. Ghosting = cleaning blade. Vertical lines = dirty corona or drum scratch.

3

APIPA (169.254.x.x) is always a DHCP failure indicator, not a valid configuration. Diagnose the DHCP server and client VLAN before anything else.

4

Use ping in sequence: 127.0.0.1 → own IP → gateway → remote IP → hostname. Each step isolates a different layer of the network stack.

5

Swollen mobile batteries are a fire hazard. Stop use immediately, do not charge, and dispose at an electronics recycling facility. No exceptions.

6

Tone generator and probe traces cables; cable tester verifies pin-to-pin continuity; cable certifier validates performance against TIA/EIA standards. Know which tool each scenario requires.

7

Inkjet: the cartridge is almost always the problem. Replace it first. Laser: always check the consumable (toner cartridge/drum) before blaming the printer mechanism.

8

Stuck print queue: stop Print Spooler, delete files in C:\Windows\System32\spool\PRINTERS, restart Print Spooler. This resolves the majority of stuck queue issues on Windows.