Sony TRINITRON KV-20EXR20 Service Manual page 3

KV-20EXR20
RM-Y103
SAFETY CHECK-OUT
(US Model only)
To Exposed Metal
Parts on Set
AC
voltmeter
lime] (0.75)
= Earth Ground
Fig. A. Using an AC voltmeter to check AC leakage.
LEAKAGE TEST
The AC leakage from any exposed metal part to
earth ground and from al} exposed metal parts to any
exposed metal part having a return to chassis, must
not exceed 0.5mA (S00 microampers). Leakage
current can be measured by any one of three
methods.
1. A commercial leakage tester, such as the
Simpson 229 or RCA WT-S40A. Follow the
manufacturers' instructions to use these instru-
ments.
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 volt-
meter. The 'limit' indication is 0.75V, so
analog meters must have an accurate low-
voltage scale. The Simpson 250 and Sanwa
SH-63Trd are examples of a passive VOM that
is suitable. Nearly all battery operated digital
multimeters that have a 2V AC range are
suitable. (See Fig. A)
Trouble Light
Ohmmeter
= AC Outlet Box
Cold-water Pipe
Fig. B. Checking for earth ground.