SAFETY CHECK-OUT
After correcting the original service problem, perform the following
safety check before releasing the set to the customer :
Check the antenna terminals, metal trim, "metallized" knobs, screws,
and all other exposed metal parts for AC leakage. Check leakage as
described below.
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 re-
turn to chassis, must not exceed 0.5mA (500 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-540A. Follow the manufacturers’ instructions to use these
instruments.
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 0.75V,
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)
Earth Ground
Fig. A. Using an AC voltmeter to check AC leakage.
AC
Voltmeter
(0.75V)
0.15 F
µ
1.5k
Ω
To Exposed Metal
Parts on Set
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