Document Outline

• About this manual
• Chapter 1. Safety information
  • General safety
  • Electrical safety
  • Safety inspection guide
  • Handling devices that are sensitive to electrostatic discharge
  • Grounding requirements
  • Safety notices (multilingual translations)
  • Laser compliance statement (multilingual translations)
• Chapter 2. Important service information
  • Strategy for replacing FRUs
    • Strategy for replacing a hard disk drive
    • Important notice for replacing a system board
    • How to use error message
  • Strategy for replacing FRUs for CTO, CMV, and GAV
    • Product definition
    • FRU identification for CTO, CMV, and GAV products
• Chapter 3. General checkout
  • What to do first
  • Checkout guide
    • Diagnostics using PC-Doctor for DOS
    • Lenovo ThinkVantage Toolbox
    • FRU tests
  • Power system checkout
    • Checking the ac power adapter
    • Checking operational charging
    • Checking the battery pack
    • Checking the backup battery
• Chapter 4. Related service information
  • Restoring the factory contents by using Recovery Disc Set
  • Passwords
    • Power-on password
    • Hard-disk password
    • Supervisor password
    • How to remove the power-on password
    • How to remove the hard-disk password
  • Power management
    • Screen blank mode
    • Sleep (standby) mode
    • Hibernation mode
  • Symptom-to-FRU index
    • Numeric error codes
    • Error messages
    • Beep symptoms
    • No-beep symptoms
    • LCD-related symptoms
    • Intermittent problems
    • Undetermined problems
• Chapter 5. Status indicators
• Chapter 6. Fn key combinations
• Chapter 7. FRU replacement notices
  • Screw notices
  • Retaining serial numbers
    • Restoring the serial number of the system unit
    • Retaining the UUID
    • Reading or writing the ECA information
• Chapter 8. Removing and replacing a FRU
  • Before servicing ThinkPad T420 and T420i
  • 1010 Battery pack
  • 1020 ExpressCard blank bezel
  • 1030 Serial Ultrabay Enhanced device or travel bezel
  • 1040 Hard disk drive (HDD) and solid state drive (SSD)
  • 1050 DIMM slot cover
  • 1060 DIMM (in the slot on the underside of the computer)
  • 1070 PCI Express Mini Card for wireless WAN
  • 1080 Keyboard
  • 1090 DIMM (in the slot under the keyboard)
  • 1100 Backup battery
  • 1110 PCI Express Mini Card for wireless LAN
  • 1120 Keyboard bezel assembly, FPC cable, and Bluethooth daughter card
  • 1130 SmartCard
  • 1140 Modem daughter card (MDC)
  • 1150 Speaker assembly
  • 1160 LCD unit
  • 1170 Fan assembly
  • 1180 CPU
  • 1190 Base cover assembly and DC-in connector cable
  • 1200 Magnesium structure frame
  • 1210 System board and ExpressCard slot assembly
  • 1220 mSATA solid state drive
  • 2010 LCD bezel assembly
  • 2020 LED board
  • 2030 Integrated camera
  • 2040 LCD panel and LCD cable
  • 2050 Camera cable
  • 2060 Wireless LAN antenna assembly or wireless LAN/WAN antenna assembly
  • 2070 Hinges and LCD rear cover assembly
• Chapter 9. Locations
  • Front view
  • Rear view
  • Bottom view
• Chapter 10. Parts list
  • Overall
  • LCD FRUs
  • Keyboard
  • Miscellaneous parts
  • Information about ac power adapters
  • Power cords
  • Recovery discs
  • Common service tools
• Appendix A. Notices
  • Electronic emissions notices
  • Trademarks