Sony STR-DA7ES Service Manual page 6

STR-DA4ES/DA7ES/VA333ES
After correcting the original service problem, perform the fol-
lowing safety checks 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
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 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 0.75
V, so analog meters must have an accurate low-voltage scale.
The Simpson 250 and Sanwa SH-63Trd are examples of a pas-
sive VOM that is suitable. Nearly all battery operated digital
multimeters that have a 2V AC range are suitable. (See Fig. A)
6
SAFETY CHECK-OUT
(US model only)
EXTENSION CABLE AND SERVICE POSITION
When repairing or serving this set, connect the jig (extension cable)
as shown below.
• Connect the Digital board (CN2102) and the E-Vol board
(CNP402) with the extension cable (Part No. J-2501-049-A).
To Exposed Metal
Parts on Set
0.15 µ F
Fig. A. Using an AC voltmeter to check AC leakage.
Notes on chip component replacement
• Never reuse a disconnected chip component.
• Notice that the minus side of a tantalum capacitor may be
damaged by heat.
J-2501-049-A
CN2102
DIGITAL board
AC
Voltmeter
1.5 k Ω
(0.75 V)
Earth Ground
E-VOL board
CNP402