Read Sony KDL-32EX725 / KDL-40EX725 / KDL-46EX725 / KDL-55EX725 Service Manual online
KDL-32EX725/40EX725/46EX725/55EX725 7
SECTION 1 - SAFETY AND FEATURES
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, such as the Simpson 229 or RCA WT-
540A. Follow the manufacturers’ instructions to use these instructions.
2. A battery-operated AC milliammeter. The Data Precision 245 digital
multimeter is suitable for this job.
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.The Simpson’s
250 and Sanwa SH-63TRD are examples of passive VOMs that are
suitable. Nearly all battery-operated digital multimeters that have a 2
VAC range are suitable (see Figure A).
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 60-to 100-watt trouble-light
(not a neon 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).
Trouble Light
AC Outlet Box
Figure B. Checking for earth ground.
To Exposed Metal
Parts on Set
0.15 µF
Earth Ground
AC
Voltmeter
(0.75V)
Figure A. Using an AC voltmeter to check AC leakage.
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