1. Precautions
1.Be sure that all of the built-in protective devices are replaced. Restore any missing protective shields.
2.When reinstalling the chassis and its assemblies, be sure to restore all pretective devices, including : control knobs and compartment covers.
3.Make sure that there are no cabinet openings through which people--particularly children --might insert fingers and contact dangerous voltages. Such openings include the spacing between the picture tube and the cabinet mask, excessively wide cabinet ventilation slots, and improperly fitted back covers.
If the measured resistance is less than 1.0 megohm or greater than 5.2 megohms, an abnormality exists that must be corrected before the unit is returned to the customer.
4.Leakage Current Hot Check (See Fig. 1) : Warning : Do not use an isolation transformer during this test. Use a leakage current tester or a metering system that complies with American National Standards Institute (ANSI C101.1,
Leakage Current for Appliances), and Underwriters Laboratories (UL Publication UL1410, 59.7).
5.With the unit completely reassembled, plug the AC line cord directly the power outlet. With the unit’s AC switch first in the ON position and then OFF, measure the current between a known erath ground (metal water pipe, conduit, etc.) and all exposed metal parts, including : antennas, handle brackets, metal cabinets, screwheads and control shafts. The current measured should not exceed 0.5 milliamp. Reverse the power-plug prongs in the AC outlet and repeat the test.
6.X-ray Limits :
The picture tube is designed to prohibit X-ray emissions. To ensure continued X-ray protection, replace the picture tube only with one that is the same type as the original.
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(Reading should |
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not be above |
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Device |
0.5mA) |
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Leakage |
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Under |
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Test |
Currant |
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Test all |
Tester |
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exposed metal |
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surfaces |
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2-Wire Cord |
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Also test with |
Earth |
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plug reversed |
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Ground |
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(using AC adapter |
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plug as required) |
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Fig. 1-1 AC Leakage Test
7. Antenna Cold Check :
With the unit’s AC plug disconnected from the AC source, connect an electrical jumper across the two AC prongs. Connect one lead of the ohmmeter to an AC prong.
Connect the other lead to the coaxial connector.
8.High Voltage Limit :
High voltage must be measured each time servicing is done on the B+, horizontal deflection or high voltage circuits.
Heed the high voltage limits. These include the
X-ray protection Specifications Label, and the Product Safety and X-ray Warning Note on the service data schematic.
9.Some semiconductor (“solid state”) devices are easily damaged by static electricity.
Such components are called Electrostatically Sensitive Devices (ESDs); examples include integrated circuits and some field-effect transistors. The following techniques will reduce the occurrence of component damage caused by static electricity.
10.Immediately before handling sny semiconductor 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.)
Samsung Electronics |
1-1 |
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