XBR-55X800B - Sony TV Service Manual (repair manual). Page 4

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XBR-55X800B iii
CAUTIONS AND WARNINGS
LEAKAGE TEST
The AC leakage from any exposed metal part to earth ground and from all 
exposed metal parts to any exposed metal part having a return to chassis, 
must  not  exceed  0.5  mA  (500  microamperes).  Leakage  current  can  be 
measured by any one of three methods.
1. 
A commercial leakage tester.  
Follow the manufacturers’ instructions provided with the tester.
2. 
A battery-operated AC milliammeter. 
3. 
Measuring the voltage drop across a resistor by means of a VOM 
or battery-operated AC voltmeter. The “limit” indication is 0.75 V, so 
analog meters must have an accurate low voltage scale. Nearly all 
battery-operated digital multimeters that have a 2 VAC range are 
suitable. (see Figure A)
To Exposed Metal
Parts on Set
0.15 µF
Earth Ground
AC
Voltmeter
(0.75V)
Figure A. Use an AC voltmeter to check AC leakage.
HOW TO FIND A GOOD EARTH GROUND
The cover-plate retaining screw on most AC outlet boxes is at earth ground. 
Verify  the AC  outlet  box  retaining  screw  ground  by  connecting  a  60W  to 
100W incandescent (not a neon or fluorescent lamp) between the hot side of 
the receptacle and the retaining screw. Try both slots, if necessary, to locate 
the hot side on the line; the lamp should light at normal brilliance if the screw 
is at ground potential. (see Figure B)
Figure B. Checking for earth ground.
Trouble Light
AC Outlet Box
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