Desktop Computer Hardware Maintenance Manual

If any unsafe conditions are present, you must determine how serious the apparent
hazard could be and whether you can continue without first correcting the
problem.
Consider these conditions and the safety hazards they present:
v Electrical hazards, especially primary power (primary voltage on the frame can
cause serious or fatal electrical shock).
v Explosive hazards, such as a damaged CRT face or bulging capacitor
v Mechanical hazards, such as loose or missing hardware
The guide consists of a series of steps presented in a checklist. 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 frame ground.
b. The power cord should be the appropriate type as specified in the parts
listings.
c. Insulation must not be frayed or worn.
4.
Remove the cover.
5. Check for any obvious alterations. Use good judgment as to the safety of any
alterations.
6. 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.
7. Check for worn, frayed, or pinched cables.
8. Check that the power-supply cover fasteners (screws or rivets) have not been
removed or tampered with.
Handling electrostatic discharge-sensitive devices
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:
v Keep the parts in protective packages until they are inserted into the product.
v Avoid contact with other people while handling the part.
v Wear a grounded wrist strap against your skin to eliminate static on your body.
6 Hardware Maintenance Manual