Lenovo T420i About this manual

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.

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