Read Sony KDL-22BX325 / KDL-32BX325 / KDL-32BX326 / KDL-32BX425 / KDL-40BX425 Service Manual online
KDL-22BX325/32BX325/32BX326/32BX425/40BX425
4
SAFETY CHECK-OUT
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 milliampmeter. 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.
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