About this manual
This manual contains service and reference information for the following ThinkPad
ThinkPad T420 and T420i
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
Machine Type 4177, 4178, 4179, 4180, 4236, 4237, and 4238
®
products.
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