Sony AC-V60A - Service Manual Safety Checks; AC Leakage Test Procedure

AC-V60A/V65A
SAFETY CHECK-OUT
After correcting the original service problem, perform the following
safety checks before releasing the set to the customer:
1. Check the area of your repair for unsoldered or
poorly-soldered connections. Check the entire
board surface for solder splashes and bridges.
oD Check the interboard wiring to ensure that no
wires are “pinched” or contact high-wattage
resistors.
:
|
3. Look for unauthorized replacement parts, par-
ticularly transistors, that were installed during.a
previous repair. Point them out to the customer
and recommend their replacement. |
which, though functioning, show
4. Look for parts
obvious signs of deterioration. Point them out
to the customer and recommend their replace-
ment.
$. Check the line cord for cracks and abrasion.
Recommend the replacement of any such line
cord to the customer.
6. Check the B+ voltage to see it is at the values
specified.
7. Check the antenna terminals,
“metallized’”” knobs, screws, and all
exposed metal parts for AC leakage.
leakage as described below.
metal trim,
other
Check
To Exposed Metal
Parts on Set
AC
voltmeter
{0.75 V)
Earth Ground
Fig. A. Using an AC voltmeter to check AC leakage.
SAFETY-RELATED COMPONENT WARNING!!
COMPONENTS IDENTIFIED BY SHADING AND MARK
ON THE SCHEMATIC DIAGRAMS, EXPLODED
VIEWS AND IN THE PARTS LIST ARE CRITICAL TO
SAFE OPERATION. REPLACE THESE COMPONENTS
WITH SONY PARTS WHOSE PART NUMBERS APPEAR
AS
SHOWN
IN
THIS
MANUAL
OR
IN
SUPPLEMENTS
PUBLISHED
BY
SONY.
CIRCUIT
ADJUSTMENTS
THAT
ARE
CRITICAL
TO
SAFE
OPERATION
ARE
IDENTIFIED
IN
THIS
MANUAL.
FOLLOW
THESE
PRO-
CEDURES
WHENEVER
CRITICAL
COMPONENTS
ARE
REPLACED
OR
IMPROPER
OPERATION
IS
SUSPECTED.
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 0.5mA (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 instru-
3 +
nents.
=
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)
ATTENTION AU COMPOSANT AYANT RAPPORT
A LA ’SECURITE!! ;
LES COMPOSANTS IDENTIFIES PAR UN TRAME ET
UNE MARQUE SUR LES DIAGRAMMES SCHE-
MATIQUES, LES VUES EXPLOSEES ET LA LISTE DES
PIECES SONT CRITIQUES POUR LA SECURITE DE
FONCTIONNEMENT. NE REMPLACER CES COMPO.
SANTS QUE PAR DES PIECES SONY DONT LES
NUMEROS SONT DONNES DANS CE MANUEL OU DES
SUPPLEMENTS PUBLIES PAR SONY. LES REGLAGES
DU CIRCUIT QUI SONT CRITIQUES POUR LA SE-
CURITE DE FONCTIONNEMENT SONT IDENTIFIES -
DANS CE MANUEL.
PLACES OU LE FONCTIONNEMENT IMPROPRE EST
SUSPECTE. | |
SUIVRE LES PROCEDURES =
QUAND LES COMPOSANTS CRITIQUES SONT REM. ~