Lenovo ThinkPad A31p ThinkPad A30/p, A31/p Hardware Maintenance Manual (Septem - Page 23

Safety information 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 a bulging capacitor v 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 frame ground. b. The power cord should be the type specified in the parts list. c. Insulation must not be frayed or worn. 4. Remove the cover. 5. Check for any obvious non-IBM alterations. Use good judgment as to the safety of any non-IBM 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 devices that are sensitive to electorostatic 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 Introduction 19