Safety; General Safety Procedure; Safety Guidelines For High-Voltage Testing - HP 9020 Service Manual

General Information
1-5
Safety
WARNING
LETHAL VOLTAGES ARE PRESENT INSIDE THE COMPUTER.
OBSERVE ALL WARNINGS IN THIS MANUAL, AND OBSERVE
THE FOLLOWING SAFETY PROCEDURES AND GUIDELINES.
General Safety Procedure
• Do all possible operations with the computer unplugged from the power source.
• If installation, maintenance, or repair must be done with the computer energized, take the
following precautions:
a. Never work alone in high-voltage areas. In case of accidental shock, a life may depend
on rapid removal from the energized source and appropriate first -aid action.
b. Employees working in high-voltage areas should know where to obtain respiratory
resuscitation and/or cardiopulmonary resuscitation (CPR), in case a fellow worker needs
assistance.
c. In case of burns, treat only after the person is breathing and has a normal heartbeat.
• If primary wiring change is made, perform continuity test between power cord ground and
metal chassis. Record results on Repair Order.
These simple precautions can save a life.
Safety Guidelines for High-Voltage Testing
Here is a list of safety guidelines to be followed when working with voltages in excess of SOV dc or
SOV ac root-mean-square (RMS).
1. Know each step of the test procedure. Check the test setup to be sure the instruments are
connected properly and that all control settings are correct.
2. Never defeat interlocks.
3. Never have one hand on chassis or other ground while measuring high voltages with a probe
held in the other hand. Use the one hand method, that is, probe in one hand, the other hand
behind the back or in a pocket.
4. Make sure the probe being used has voltage insulation higher than the voltage being mea-
sured. Check wires and probes for cracked insulation and defects. If any defects are noted do
not use until repairs are made.
5. Make certain that the instrument to be serviced is turned off and all capacitors, CRTs, and
high-voltage circuits are discharged before any component or hardware is removed or
touched. Remember that a circuit can be lethally charged if a component is open or missing,
or if a wire is disconnected or open, even with the ac power switch off. Isolated heat sinks can
also be statically charged.
6. Make certain that instruments used for testing are used within their rated specification. Never
use instruments floated above their specified rating.
7. Never reach around energized high voltage circuits. Always turn equipment off and discharge
the high voltage first.