Sony KDE42XBR950 Service Manual page 3

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-sol-
dered connections. Check the entire board surface for solder
splashes and bridges.
2. Check the interboard wiring to ensure that no wires are
"pinched" or contact high-wattage resistors.
3. Check that all control knobs, shields, covers, ground straps,
and mounting hardware have been replaced. Be absolutely
certain that you have replaced all the insulators.
4. Look for unauthorized replacement parts, particularly tran-
sistors, that were installed during a previous repair. Point them
out to the customer and recommend their replacement.
5. Look for parts which, though functioning, show obvious signs
of deterioration. Point them out to the customer and recom-
mend their replacement.
6. Check the line cords for cracks and abrasion. Recommend
the replacement of any such line cord to the customer.
7. Check the antenna terminals, metal trim, "metallized" knobs,
screws, and all other exposed metal parts for AC Leakage.
Check leakage as described right.
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" indica-
tion 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 VOMs that are suitable. Nearly all bat-
tery operated digital multimeters that have a 2 V AC range
are suitable. (See Fig. A)
To Exposed Metal
Parts on Set
0.15 F
Fig. A. Using an AC voltmeter to check AC leakage.
AC
1.5 k Voltmeter
(0.75 V)
Earth Ground
WARNING!!
SAFETY-RELATED COMPONENT WARNING!!
COMPONENTS IDENTIFIED BY SHADING AND MARK
! ON THE SCHEMATIC DIAGRAMS, EXPLODED
VIEWS AND IN THE PARTS LIST ARE CRITICAL FOR
SAFE OPERATION. REPLACE THESE COMPONENTS
WITH SONY PARTS WHOSE PART NUMBERS AP-
PEAR AS SHOWN IN THIS MANUAL OR IN SUPPLE-
MENTS PUBLISHED BY SONY. CIRCUIT ADJUST-
MENTS THAT ARE CRITICAL FOR SAFE OPERATION
ARE IDENTIFIED IN THIS MANUAL. FOLLOW THESE
PROCEDURES WHENEVER CRITICAL COMPONENTS
ARE REPLACED OR IMPROPER OPERATION IS
SUSPECTED.
AVERTISSEMENT!!
ATTENTION AUX COMPOSANTS RELATIFS À LA
SÉCURITÉ!!
LES COMPOSANTS IDENTIFIÉS PAR UNE TRAME ET
UNE MARQUE ! SONT CRITIQUES POUR LA SÉCURITÉ.
NE LES REMPLACER QUE PAR UNE PIÈCE PORTANT
LE NUMÉRO SPECIFIÉ. LES RÉGLAGES DE CIRCUIT
DONT L'IMPORTANCE EST CRITIQUE POUR LA
SÉCURITÉ DU FONCTIONNEMENT SONT IDENTIFIÉS
DANS LE PRÉSENT MANUEL.
PROCÉDURES LORS DE CHAQUE REMPLACEMENT DE
COMPOSANTS CRITIQUES, OU LORSQU'UN MAUVAIS
FONCTIONNEMENT EST SUSPECTÉ.
KDE42XBR950/KDE50XBR950 (UC)
SUIVRE CES
3