Lenovo ThinkCentre M75n, Hardware Maintenance Manual, Page: 3 / 120

Contents
About this manual . . . . . . . . . . . . iii
Chapter 1. Important safety
information . . . . . . . . . . . . . . . . 1
General safety . . . . . . . . . . . . . . . . 1
Electrical safety . . . . . . . . . . . . . . . . 2
Safety inspection guide . . . . . . . . . . . . . 3
Handling electrostatic discharge-sensitive
devices . . . . . . . . . . . . . . . . . . . 4
Grounding requirements . . . . . . . . . . . . 4
Safety notices (multi-lingual translations) . . . . . . 4
Chapter 2. Important service
information . . . . . . . . . . . . . . . 27
Strategy for replacing FRUs . . . . . . . . . . 27
Strategy for replacing a hard disk drive or a
solid-state drive . . . . . . . . . . . . . 27
Important notice for replacing a system
board . . . . . . . . . . . . . . . . . 27
How to use error codes . . . . . . . . . . 27
Strategy for replacing FRUs for CTO, special-bid,
and standard models. . . . . . . . . . . . . 28
Product definition . . . . . . . . . . . . 28
FRU identification . . . . . . . . . . . . 28
Chapter 3. Product overview . . . . . 29
Top . . . . . . . . . . . . . . . . . . . 29
Front . . . . . . . . . . . . . . . . . . . 30
Rear . . . . . . . . . . . . . . . . . . . 31
Bottom . . . . . . . . . . . . . . . . . . 32
Chapter 4. Service checkout and
symptom-to-FRU index . . . . . . . . 33
Service checkout . . . . . . . . . . . . . . 33
Problem determination tips . . . . . . . . 33
Symptom-to-FRU index . . . . . . . . . . . 34
Hard disk drive boot error . . . . . . . . . 34
Power supply problems . . . . . . . . . . 35
Beep symptoms . . . . . . . . . . . . . 35
POST error codes . . . . . . . . . . . . 36
Miscellaneous error conditions . . . . . . . 37
Undetermined problems
. . . . . . . . . 39
Chapter 5. Troubleshooting,
diagnostics, and recovery . . . . . . . 41
Basic procedure for resolving computer
problems . . . . . . . . . . . . . . . . . 41
Troubleshooting
. . . . . . . . . . . . . . 41
Startup problems . . . . . . . . . . . . 42
Audio problems . . . . . . . . . . . . . 43
Network problems . . . . . . . . . . . . 43
Performance problems . . . . . . . . . . 46
Storage drive problems . . . . . . . . . . 47
CD or DVD problems . . . . . . . . . . . 47
Serial connector problems . . . . . . . . . 48
USB device problems
. . . . . . . . . . 48
Software problems . . . . . . . . . . . . 49
Diagnostics . . . . . . . . . . . . . . . . 49
Lenovo diagnostic tools . . . . . . . . . . 49
UEFI diagnostic program . . . . . . . . . 49
Recovery . . . . . . . . . . . . . . . . . 50
Restore system files and settings to an earlier
point . . . . . . . . . . . . . . . . . 50
Restore your files from a backup . . . . . . 50
Reset your computer . . . . . . . . . . . 50
Use advanced options . . . . . . . . . . 50
Windows automatic recovery. . . . . . . . 51
Create and use a recovery USB device . . . . 51
Update the device driver
. . . . . . . . . 51
Chapter 6. Hardware removal and
installation . . . . . . . . . . . . . . . 53
Handling static-sensitive devices . . . . . . . . 53
Service tool kit . . . . . . . . . . . . . . . 53
Major FRUs and CRUs (fan models) . . . . . . . 54
Major FRUs and CRUs (fanless models) . . . . . 55
System board
. . . . . . . . . . . . . . . 58
Removing and installing hardware (fan models) . . 59
External options . . . . . . . . . . . . . 59
Power adapter and power cord . . . . . . . 60
DIN rail bracket kit . . . . . . . . . . . . 61
Power adapter bracket kit . . . . . . . . . 63
VESA mount bracket kit . . . . . . . . . . 67
Rear Wi-Fi antenna. . . . . . . . . . . . 68
Bottom cover . . . . . . . . . . . . . . 69
Wi-Fi card . . . . . . . . . . . . . . . 71
M.2 solid-state drive . . . . . . . . . . . 72
Computer cover and rear I/O bracket
. . . . 73
Coin-cell battery . . . . . . . . . . . . . 75
System fan . . . . . . . . . . . . . . . 76
Internal speaker . . . . . . . . . . . . . 77
Heat sink
. . . . . . . . . . . . . . . 78
System board . . . . . . . . . . . . . . 79
Front Wi-Fi antenna and cable . . . . . . . 81
Rear Wi-Fi antenna cable . . . . . . . . . 82
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