Leakage Test - Sony STR-DG720 Service Manual

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SAFETY CHECK-OUT (US MODEL)
After correcting the original service problem, perform the follow-
ing 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
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
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 passive VOM that is suitable. Nearly all battery operated
digital multimeters that have a 2 V AC range are suitable. (See
Fig. A)
To Exposed Metal
Parts on Set
TE
L 13942296513
0.15 μF
Fig. A. Using an AC voltmeter to check AC leakage.
SAFETY-RELATED COMPONET WARNING!
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COMPONENTS IDENTIFIED BY MARK 0 OR DOTTED LINE
WITH MARK 0 ON THE SCHEMATIC DIAGRAMS AND IN
THE PARTS LIST ARE CRITICAL TO SAFE OPERATION.
REPLACE THESE .
WHOSE PART NUMBERS APPEAR AS SHOWN IN THIS
MANUAL OR IN SUPPLEMENTS PUBLISHED BY SONY.
http://www.xiaoyu163.com
AC
1.5 kΩ voltmeter
(0.75 V)
Earth Ground
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COMPONENTS i WITH SONY
http://www.xiaoyu163.com
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MODEL IDENTIFICATION
–BACK PANEL–
Model
US
CND
AEP, UK
• Abbreviation
CND : Canadian model
Notes on chip component replacement
• Never reuse a disconnected chip component.
• Notice that the minus side of a tantalum capacitor may be dam-
aged by heat.
UNLEADED SOLDER
Boards requiring use of unleaded solder are printed with the lead-
free mark (LF) indicating the solder contains no lead.
(Caution: Some printed circuit boards may not come printed with
the lead free mark due to their particular size)
: LEAD FREE MARK
Unleaded solder has the following characteristics.
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• Unleaded solder melts at a temperature about 40 °C higher
than ordinary solder.
Ordinary soldering irons can be used but the iron tip has to be
applied to the solder joint for a slightly longer time.
Soldering irons using a temperature regulator should be set to
about 350 °C.
Caution: The printed pattern (copper foil) may peel away if the
heated tip is applied for too long, so be careful!
• Strong viscosity
Unleaded solder is more viscous (sticky, less prone to fl ow)
than ordinary solder so use caution not to let solder bridges
occur such as on IC pins, etc.
• Usable with ordinary solder
It is best to use only unleaded solder but unleaded solder may
also be added to ordinary solder.
Special Component Notice
The components identifi ed by mark 9 contain confi dential infor-
mation.
Strictly follow the instructions whenever the components are re-
paired and/or replaced.
Notice pour composants spéciaux
Les composants identifi és par la marque 9 contiennent des infor-
mations confi dentielles.
Suivre scrupuleusement les instructions chaque fois qu'un com-
posant est remplacé et / ou réparé.
ATTENTION AU COMPOSANT AYANT RAPPORT
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LES COMPOSANTS IDENTIFIÉS PAR UNE MARQUE 0 SUR
LES DIAGRAMMES SCHÉMATIQUES ET LA LISTE DES
PARTS PIÈCES SONT CRITIQUES POUR LA SÉCURITÉ DE FONC- .
TIONNEMENT. NE REMPLACER CES COM- POSANTS QUE
PAR DES PIÈCES SONY DONT LES NUMÉROS SONT DON-
NÉS DANS CE MANUEL OU DANS LES SUPPLÉMENTS
PUBLIÉS PAR SONY.
STR-DG720
9 4 2 8
Part No.
Part No.
3-093-898-0[]
3-093-898-1[]
3-093-898-2[]
0 5 8 2 9 9 4 2 8
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À LA SÉCURITÉ!
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9 9
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