IBM 7940, Problem Determination And Service Manual

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Guidelines for trained service technicians
This section contains information for trained service technicians.
Inspecting for unsafe conditions
Use the information in this section to help you identify potential unsafe conditions in
an IBM product that you are working on. Each IBM product, as it was designed and
manufactured, has required safety items to protect users and service technicians
from injury. The information in this section addresses only those items. Use good
judgment to identify potential unsafe conditions that might be caused by non-IBM
alterations or attachment of non-IBM features or optional devices that are not
addressed in this section. If you identify an unsafe condition, you must determine
how serious the hazard is and whether you must correct the problem before you
work on the product.
Consider the following conditions and the safety hazards that 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 inspect the product for potential unsafe conditions, complete the following steps:
1. Make sure that the power is off and the power cord is disconnected.
2. Make sure that the exterior cover is not damaged, loose, or broken, and
observe any sharp edges.
3. Check the power cord:
v
Make sure that the third-wire ground connector is 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.
v
Make sure that the power cord is the correct type, as specified in “Power
cords” on page 25.
v Make sure that the insulation is not 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 server for any obvious unsafe conditions, such as metal filings,
contamination, water or other liquid, or signs of fire or smoke damage.
7. Check for worn, frayed, or pinched cables.
8. Make sure that the power-supply cover fasteners (screws or rivets) have not
been removed or tampered with.
Guidelines for servicing electrical equipment
Observe the following guidelines when you service electrical equipment:
v
Check the area for electrical hazards such as moist floors, nongrounded power
extension cords, power surges, and missing safety grounds.
v Use only approved tools and test equipment. Some hand tools have handles that
are covered with a soft material that does not provide insulation from live
electrical currents.
v
Regularly inspect and maintain your electrical hand tools for safe operational
condition. Do not use worn or broken tools or testers.
viii
IBM System x3455 Type 7940 and 7941: Problem Determination and Service Guide