Lenovo ThinkPad P50 Hardware Maintenance Manual Download

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Consider these conditions and the safety hazards they present:
• Electrical hazards, especially primary power (primary voltage on the frame can cause serious or fatal

electrical shock)

• Explosive hazards, such as a damaged CRT face or a bulging capacitor
• Mechanical hazards, such as loose or missing hardware

To determine whether there are any potentially unsafe conditions, use the following checklist at the beginning
of every service task. Begin the checks with the power off, and the power cord disconnected.

Checklist:

1. Check exterior covers for damage (loose, broken, or sharp edges).

2. Power off the computer. Disconnect the power cord.

3. Check the power cord for:

a. A third-wire ground connector in good condition. Use a meter to measure third-wire ground

continuity for 0.1 ohm or less between the external ground pin and the frame ground.

b. The power cord should be the authorized type specified for your computer. Go to:

http://www.lenovo.com/serviceparts-lookup

c. Insulation must not be frayed or worn.

4. Check for cracked or bulging batteries.

5. Remove the cover.

6. Check for any obvious non-ThinkPad alterations. Use good judgment as to the safety of any

non-ThinkPad alterations.

7. Check inside the unit for any obvious unsafe conditions, such as metal filings, contamination, water or

other liquids, or signs of fire or smoke damage.

8. Check for worn, frayed, or pinched cables.

9. Check that the power-supply cover fasteners (screws or rivets) have not been removed or tampered with.

Handling devices that are sensitive to electrostatic discharge

Any computer part containing transistors or integrated circuits (ICs) should be considered sensitive to
electrostatic discharge (ESD.) ESD damage can occur when there is a difference in charge between objects.
Protect against ESD damage by equalizing the charge so that the machine, the part, the work mat, and the
person handling the part are all at the same charge.

Notes:

1. Use product-specific ESD procedures when they exceed the requirements noted here.

2. Make sure that the ESD protective devices you use have been certified (ISO 9000) as fully effective.

When handling ESD-sensitive parts:
• Keep the parts in protective packages until they are inserted into the product.
• Avoid contact with other people.
• Wear a grounded wrist strap against your skin to eliminate static on your body.
• Prevent the part from touching your clothing. Most clothing is insulative and retains a charge even

when you are wearing a wrist strap.

• Use a grounded work mat to provide a static-free work surface. The mat is especially useful when

handling ESD-sensitive devices.

• Select a grounding system, such as those listed below, to provide protection that meets the specific

service requirement.

Note:

The use of a grounding system to guard against ESD damage is desirable but not necessary.

– Attach the ESD ground clip to any frame ground, ground braid, or green-wire ground.

Chapter 1

Safety information