1. Precautions
1. Be sure that all of the built-in protective devices are
(READING SHOULD
replaced. Restore any missing protective shields.
NOT BE ABOVE
0.5mA)
LEAKAGE
2. When reinstalling the chassis and its assemblies, be DEVICECURRENT
UNDERTESTER
sure to restore all protective devices, including :
TEST
control knobs and compartment covers.
TEST ALL
EXPOSED METER
3. Make sure that there are no cabinet openings SURFACES
through which people--particularly children2-WIRE CORD
--might insert fingers and contact dangerous
ALSO TEST WITH
voltages. Such openings include the spacing EARTH
PLUG REVERSEDGROUND
between the picture tube and the cabinet mask, (USING AC ADAPTER
PLUG AS REQUIRED)
excessively wide cabinet ventilation slots, and
improperly fitted back covers.
Fig. 1-1 AC Leakage Test
If the measured resistance is less than 1.0 megohm
or greater than 5.2 megohms, an abnormality exists
7. Antenna Cold Check :
that must be corrected before the unit is returned
With the unit?s AC plug disconnected from the
to the customer.
AC source, connect an electrical jumper across the
two AC prongs. Connect one lead of the ohmmeter
4. Leakage Current Hot Check (See Fig. 1-1) :to an AC prong.
Warning : Do not use an isolation transformer Connect the other lead to the coaxial connector.
during this test. Use a leakage current tester or a
metering system that complies with American 8. High Voltage Limit :
National Standards Institute (ANSI C101.1, High voltage must be measured each time
Leakage Current for Appliances), and Underwritersservicing is done on the B+, horizontal deflection
Laboratories (UL Publication UL1410, 59.7).or high voltage circuits.
5. With the unit completely reassembled, plug the ACHeed the high voltage limits. These include the
line cord directly the power outlet. With the unit?s
X-ray protection Specifications Label, and the
AC switch first in the ON position and then OFF,
Product Safety and X-ray Warning Note on the
measure the current between a known earth
service data schematic.
ground (metal water pipe, conduit, etc.) and all
exposed metal parts, including : antennas, handle9. Some semiconductor (?solid state?) devices are
brackets, metal cabinets, screwheads and control
easily damaged by static electricity.
shafts. The current measured should not exceed
Such components are called Electrostatically
0.5 milliamp. Reverse the power-plug prongs in theSensitive Devices (ESDs); examples include
AC outlet and repeat the test.integrated circuits and some field-effect transistors.
The following techniques will reduce the
6. X-ray Limits :occurrence of component damage caused by static
The picture tube is designed to prohibit X-ray electricity.
emissions. To ensure continued X-ray protection,
replace the picture tube only with one that is the 10. Immediately before handling any semiconductor
same type as the original.
components or assemblies, drain the electrostatic
charge from your body by touching a known
earth ground. Alternatively, wear a discharging
Wrist-strap device. (Be sure to remove it prior to
applying power--this is an electric shock
precaution.)
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