Safety Guidelines - Ramsey Electronics PG13 Instruction Manual

SAFETY GUIDELINES FOR HIGH VOLTAGE AND/OR LINE POWERED
EQUIPMENT
Author: Samuel M. Goldwasser
Corrections/suggestions: sam@stdavids.picker.com
Copyright (c) 1994, 1995, 1996, 1997, 1998
All Rights Reserved
Reproduction of this document in whole or in part is permitted if both of the
following conditions are satisfied:
1. This notice is included in its entirety at the beginning.
2. There is no charge except to cover the costs of copying.
Introduction
Consumer electronics equipment like TVs, computer monitors, microwave
ovens, and electronic flash units, use voltages at power levels that are
potentially lethal. Normally, these are safely enclosed to prevent accidental
contact. However, during servicing, the cabinet will likely be open and safety
interlocks may be defeated. Depending on overall conditions and your general
state of health, there is a wide variation of voltage, current, and total energy
levels that can kill.
Microwave ovens in particular are probably THE most dangerous household
appliance to service. There is high voltage - up to 5,000 V or more - at high
current - more than an amp may be available momentarily. This is an instantly
lethal combination.
TVs and monitors may have up to 35 KV on the CRT but the current is low—a
couple of milliamps. However, the CRT capacitance can hold a painful charge
for a long time. In addition, portions of the circuitry of TVs and monitors - as
well as all other devices that plug into the wall socket - are line connected. This
is actually more dangerous than the high voltage due to the greater current
available - and a few hundred volts can make you just as dead as 35 KV!
Electronic flash units and strobelights have large energy storage capacitors
which alone can deliver a lethal charge - long after the power has been
removed. This applies to some extent even to those little disposable pocket
cameras with flash!
Even some portions of apparently harmless devices like VCRs and CD
players or vacuum cleaners and toasters - can be hazardous (though the live
parts may be insulated or protected - but don't count on it!
This information also applies when working on other high voltage or line
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PG13 4