Hardware Troubleshooting

Troubleshooting Methodology

7-Step Process

1. Identify the problem
   - Gather information
   - Question users
   - Identify symptoms
   - Determine changes

2. Establish a theory of probable cause
   - Question the obvious
   - Research symptoms

3. Test the theory
   - Confirm or deny
   - If denied → new theory

4. Establish a plan of action
   - Research solutions
   - Plan before acting

5. Implement the solution
   - Document steps
   - Verify full functionality

6. Verify full system functionality
   - Test all related functions
   - Prevent recurrence

7. Document findings
   - Update KB
   - User training

Desktop/Laptop Hardware

Boot Issues

Không khởi động được

Check order:
1. Power source (adapter, battery)
2. Power button/LED
3. Fans, noises
4. POST errors (beep codes)
5. BIOS settings
6. Boot order
7. HDD/SSD detection
8. OS corruption

Common causes:
- Dead battery
- Dead adapter
- RAM faulty
- HDD failure
- MBR corrupted
- Boot sector virus

Beep codes (AMI BIOS)

1 beep:  DRAM refresh failure
2 beeps: Parity circuit failure
3 beeps: Base 64K RAM failure
4 beeps: System timer failure
5 beeps: Processor failure
6 beeps: Keyboard controller failure
7 beeps: Virtual mode exception
8 beeps: Display memory read/write failure
9 beeps: ROM BIOS checksum failure
10 beeps: CMOS shutdown register error
11 beeps: Cache memory error

RAM Issues

Symptoms:
- BSOD
- Random reboots
- Boot failures
- Application crashes
- Data corruption

Diagnosis:
- Memtest86+
- Windows Memory Diagnostic
- Swap/test RAM sticks
- Reseat RAM

Solutions:
- Replace faulty RAM
- Reseat contacts
- Update BIOS
- Check compatibility

Storage Issues

Symptoms:
- Slow performance
- Boot failures
- Clicking noises (HDD)
- Read/write errors
- SMART warnings

Diagnosis:
- CrystalDiskInfo (SMART)
- chkdsk /f /r
- sfc /scannow
- HDTune
- Manufacturer tools

Solutions:
- Replace faulty drive
- Clone to new drive (Acronis, Clonezilla)
- Recover data
- Update firmware

Display Issues

Symptoms:
- No display
- Flickering
- Artifacts
- Wrong resolution
- Dim/tinted

Diagnosis:
- Test external monitor
- Test different cable
- Safe Mode test
- Update drivers
- Check connections

Solutions:
- Reseat display cable
- Replace cable
- Update/reinstall GPU driver
- Replace display (laptop)
- Replace GPU (desktop)

Power Issues

Laptop:
- Not charging
- Battery not detected
- Shuts down randomly

Diagnosis:
- Battery health (powercfg /batteryreport)
- Test different charger
- Check DC jack
- Reset power (hold power 30s)

Desktop:
- No power
- Random shutdowns

Diagnosis:
- PSU tester
- Test PSU voltage
- Check motherboard capacitors
- Reset CMOS

Solutions:
- Replace battery
- Replace charger
- Replace DC jack
- Replace PSU
- Replace CMOS battery

Overheating

Symptoms:
- Loud fans
- Throttling
- Sudden shutdown
- Very hot surface

Diagnosis:
- HWMonitor, Core Temp
- Check fan speeds
- Visual inspection

Solutions:
- Clean dust/fans
- Replace thermal paste
- Replace faulty fans
- Improve airflow
- Undervolt CPU

Printer Troubleshooting

Common Issues

1. Not printing
2. Paper jam
3. Poor print quality
4. Offline status
5. Toner/ink issues
6. Network connectivity

Troubleshooting steps:
- Check power/connections
- Check paper/toner
- Print test page
- Check print queue
- Restart spooler
- Reinstall driver
- Network ping test

Windows Print Spooler

# Restart print spooler
Restart-Service -Name Spooler -Force

# Clear print queue
Stop-Service -Name Spooler -Force
Remove-Item -Path "C:\Windows\System32\spool\PRINTERS\*" -Force
Start-Service -Name Spooler

# List printers
Get-Printer
Get-PrinterDriver

# Add printer
Add-Printer -Name "HP-01" -DriverName "HP UPD" `
    -PortName `"IP_192.168.1.50"

Network Troubleshooting

Network Commands

# IP configuration
ipconfig /all
ipconfig /release
ipconfig /renew
ipconfig /flushdns
ipconfig /registerdns

# Connectivity
ping google.com
ping -t 8.8.8.8      # Continuous
ping -n 100 8.8.8.8  # 100 pings
tracert google.com
pathping google.com

# DNS
nslookup google.com
nslookup google.com 8.8.8.8
Resolve-DnsName google.com

# Network info
netstat -an
netstat -b
Get-NetAdapter
Get-NetIPConfiguration
Get-NetRoute

# Test port
Test-NetConnection google.com -Port 443
tnc server01 -Port 3389 -InformationLevel Detailed

# ARP
arp -a

OSI Troubleshooting

Layer 1 (Physical):
- Cable connected?
- Link LED on?
- Cable damage?
- Port working?
- Test: Cable tester, different cable

Layer 2 (Data Link):
- MAC address learned?
- VLAN correct?
- Duplex mismatch?
- Test: show mac address-table

Layer 3 (Network):
- IP address correct?
- Subnet mask correct?
- Gateway reachable?
- Routing?
- Test: ping, tracert

Layer 4 (Transport):
- Firewall blocking?
- Port open?
- Test: telnet, tnc

Layer 5-7:
- Application issues
- Authentication
- Permissions

Common Network Issues

"Không có kết nối mạng"
- Check cable
- Check WiFi
- Restart router
- ipconfig /release + /renew
- Reset TCP/IP: netsh int ip reset
- Reset Winsock: netsh winsock reset

"Không vào được website"
- Ping IP (8.8.8.8) → Check DNS
- nslookup domain
- ipconfig /flushdns
- Change DNS to 8.8.8.8

"Chậm mạng"
- Speedtest
- Check bandwidth usage
- Virus scan
- Update driver
- Cable/port quality

"WiFi yếu"
- Signal strength
- Interference (channels)
- Distance
- Number of devices
- Router placement

Mobile Device Troubleshooting

Common Issues

iOS:
- Cannot connect WiFi
- App crashes
- Battery draining
- Storage full
- Email not syncing

Android:
- Similar issues
- App force close
- Overheating
- Bluetooth issues

Solutions

1. Restart device
2. Update OS
3. Clear app cache
4. Reinstall problematic app
5. Reset network settings
6. Factory reset (last resort)

Peripheral Troubleshooting

Keyboard/Mouse

Wireless:
- Batteries
- USB receiver
- Pairing
- Interference

Wired:
- USB port test
- Cable damage
- Driver issues
- Different computer test

Monitor

- No signal: check cable, input source
- Flickering: cable, refresh rate
- Wrong resolution: settings, driver
- Dead pixels: replace if many

Docking Station

- Power adapter correct?
- Firmware update
- Driver install
- USB ports test
- Display output check

Diagnostics Tools

Windows Built-in

# System info
msinfo32
dxdiag

# Performance
perfmon

# Event Viewer
eventvwr.msc

# Task Manager
taskmgr

# Resource Monitor
resmon

# System Configuration
msconfig

# Device Manager
devmgmt.msc

# Disk Management
diskmgmt.msc

Third-party Tools

- CrystalDiskInfo: HDD/SSD health
- CPU-Z: CPU, RAM, motherboard info
- GPU-Z: GPU info
- HWiNFO: Hardware monitoring
- MemTest86: RAM test
- Prime95: CPU stress test
- FurMark: GPU stress test
- SpeedFan: Fan control
- CCleaner: System cleanup
- Hiren's BootCD: All-in-one

Hardware Replacement

Warranty Check

- Serial number lookup
- Manufacturer website
- Vendor portal (Dell, HP, Lenovo)
- Parts availability
- Onsite vs depot service

Replacement Procedure

1. Backup data (if possible)
2. Document issue
3. Raise vendor ticket/RMA
4. Get replacement
5. Restore data
6. Verify functionality
7. Update asset database
8. Dispose/recycle old

Prevention

Preventive Maintenance

- Regular updates
- Dust cleaning
- Backup verification
- Disk health monitoring
- Battery calibration
- Cable inspection
- Firmware updates
- User training

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