SAFETY CHECK-OUT
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, Ometallized� 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 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 manufacturersO 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 Olimit� indica-
tion is 0.75 V, so analog meters must have an accurate low-
voltage scale. The Simpson 250 and Sanwa SH-63Trd are ex-
amples of a passive VOM that is suitable. Nearly all battery
operated digital multimeters that have a 2 V AC range are suit-
able. (See Fig. A)
To Exposed Metal
Parts on Set
AC
0.15 ?F1.5 kWvoltmeter
(0.75 V)
Earth Ground
Fig. A. Using an AC voltmeter to check AC leakage.
Flexible Circuit Board Repairing
Y Keep the temperature of the soldering iron around 270 uC dur-
ing repairing.
Y Do not touch the soldering iron on the same conductor of the
circuit board (within 3 times).
Y Be careful not to apply force on the conductor when soldering
or unsoldering.
Notes on chip component replacement
Y Never reuse a disconnected chip component.
Y Notice that the minus side of a tantalum capacitor may be dam-
aged by heat.
ATTENTION AU COMPOSANT AYANT RAPPORT
SAFETY-RELATED COMPONENT WARNING!!� LA S?CURIT?!
COMPONENTS IDENTIFIED BY MARK ! OR DOTTEDLES COMPOSANTS IDENTIFI?S PAR UNE MARQUE !
LINE WITH MARK ! ON THE SCHEMATIC DIAGRAMSSUR LES DIAGRAMMES SCH?MATIQUES ET LA LISTE
AND IN THE PARTS LIST ARE CRITICAL TO SAFEDES PIéCES SONT CRITIQUES POUR LA S?CURIT?
OPERATION. REPLACE THESE COMPONENTS WITHDE FONCTIONNEMENT. NE REMPLACER CES COM-
SONY PARTS WHOSE PART NUMBERS APPEAR ASPOSANTS QUE PAR DES PIéCES SONY DONT LES
SHOWN IN THIS MANUAL OR IN SUPPLEMENTS PUB-NUM?ROS SONT DONN?S DANS CE MANUEL OU
LISHED BY SONY.DANS LES SUPPL?MENTS PUBLI?S PAR SONY.
� 2 � |
ACEC
