IBM 7940, Problem Determination And Service Manual

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v
Do not touch the reflective surface of a dental mirror to a live electrical circuit.
The surface is conductive and can cause personal injury or equipment damage if
it touches a live electrical circuit.
v Some rubber floor mats contain small conductive fibers to decrease electrostatic
discharge. Do not use this type of mat to protect yourself from electrical shock.
v
Do not work alone under hazardous conditions or near equipment that has
hazardous voltages.
v
Locate the emergency power-off (EPO) switch, disconnecting switch, or electrical
outlet so that you can turn off the power quickly in the event of an electrical
accident.
v Disconnect all power before you perform a mechanical inspection, work near
power supplies, or remove or install main units.
v
Before you work on the equipment, disconnect the power cord. If you cannot
disconnect the power cord, have the customer power-off the wall box that
supplies power to the equipment and lock the wall box in the off position.
v
Never assume that power has been disconnected from a circuit. Check it to
make sure that it has been disconnected.
v
If you have to work on equipment that has exposed electrical circuits, observe
the following precautions:
– Make sure that another person who is familiar with the power-off controls is
near you and is available to turn off the power if necessary.
– When you work with powered-on electrical equipment, use only one hand.
Keep the other hand in your pocket or behind your back to avoid creating a
complete circuit that could cause an electrical shock.
– When you use a tester, set the controls correctly and use the approved probe
leads and accessories for that tester.
– Stand on a suitable rubber mat to insulate you from grounds such as metal
floor strips and equipment frames.
v
Use extreme care when you measure high voltages.
v
To ensure proper grounding of components such as power supplies, pumps,
blowers, fans, and motor generators, do not service these components outside of
their normal operating locations.
v If an electrical accident occurs, use caution, turn off the power, and send another
person to get medical aid.
Safety
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