Filter
Top Products
About this manual
This manual contains service and reference information for the following ThinkPad
®
products.
ThinkPad T420 and T420i Machine Type 4177, 4178, 4179, 4180, 4236, 4237, and 4238
Use this manual along with the advanced diagnostic tests to troubleshoot problems.
Important:
This manual is intended only for trained service technicians who are familiar with ThinkPad products. Use this
manual along with the advanced diagnostic tests to troubleshoot problems effectively.
Before servicing a ThinkPad product, be sure to read all the information under Chapter 1 “Safety information” on
page 1 and Chapter 2 “Important service information” on page 23.
© Copyright Lenovo 2011
iii