PG13
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7
materials with a high resistance path between you and the chassis
(greater than 100K ohms). Never use metallic conductors as you would
then become an excellent path to ground for line current or risk
amputating your hand at the wrist when you accidentally contacted that
1000 A welder supply!
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Don't attempt repair work when you are tired. Not only will you be more
careless, but your primary diagnostic tool - deductive reasoning - will not
be operating at full capacity.
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Finally, never assume anything without checking it out for yourself! Don't
take shortcuts!
Safety tests for leakage current on repaired equipment
It is always essential to test AFTER any repairs to assure that no accessible
parts of the equipment have inadvertently been shorted to a Hot wire or live
point in the power supply. In addition to incorrect rewiring, this could result
from a faulty part, solder splash, or kinked wire insulation.
There are two sets of tests:
DC leakage: Use a multimeter on the highest ohms range to measure the
resistance between the Hot/Neutral prongs of the wall plug (shorted together
and with the power switch on where one exists) to ALL exposed metal parts of
the equipment including metallic trim, knobs, connector shells and shields,
VHF and UHF antenna connections, etc.
This resistance must not be less than 1M ohm.
AC leakage: Connect a 1.5K ohm, 10 Watt resistor in parallel with a 0.15 uF,
150 V capacitor. With your multimeter set on ACV across this combination
and the equipment powered up, touch between a known earth ground and
each exposed metal part of the equipment as above.
WARNING: Take care not to touch anything until you have confirmed that
the leakage is acceptable - you could have a shocking experience! The
potential measured for any exposed metal surface must not exceed 0.75 V.
If the equipment fails either of these tests, the fault MUST be found and
corrected before putting it back in service (even if you are doing this for your
in-laws!).
Some notes regarding the above safety information
While the PG13 falls under the high voltage category, many of the safety
recommendations do not apply due to the nature of high frequency high
Содержание PG13
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