Lenovo ThinkPad Edge E420s Hardware Maintenance Manual page 83

• Avoid rough handling of any kind.
• At every point in the process, be sure not to drop or stack the system board.
• If you put a system board down, be sure to put it only on a padded surface such as an ESD mat or a corrugated
conductive surface.
If your computer supports PC-Doctor for DOS, after replacing the system board, run PC-Doctor for DOS to make sure
that the HDD Active Protection System still functions. The procedure is as follows:
1. Place the computer on a horizontal surface.
2. Run Diagnostics ➙ ThinkPad Devices ➙ HDD Active Protection Test.
Attention: Do not apply physical shock to the computer while the test is running.
For access, remove these FRUs in order:
• "1020 Hard disk drive or solid state drive assembly" on page 60
• "1030 Keyboard" on page 61
• "1040 Top case assembly" on page 63
• "1090 Battery pack" on page 68
• "1120 PCI Express Mini Card for wireless LAN" on page 71
• "1130 PCI Express Mini Card for wireless WAN" on page 72
• "1130 mSATA solid state drive" on page 73
• "1100 Optical drive or travel cover" on page 69
• "1140 Bluetooth daughter card" on page 75
• "1150 Media Card Reader slot board assembly" on page 75
• "1180 LCD unit" on page 80
• "2010 LCD bezel assembly" on page 82
Removal steps of system board
Step Screw (quantity)
2
M2 × 4 mm, wafer-head, nylon-coated (3)
Torque
Color
Black 0.181 Nm
(1.85 kgfcm)
.
Chapter 8 Removing and replacing a FRU
77