Compaq D-1H - Manual (Page 3)

— 3 —
P75
1.5 k W 0.15 µF
AC
Voltmeter
(0.75 V)
To Exposed Metal
Parts on Set
Earth Ground
SAFETY CHECK-OUT
(US Model only)
After correcting the original service problem, perform
the following safety checks before releasing the set to the
customer: 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 microampere).
Leakage current can be measured by any one of three methods.
W A R N I N G ! ! W A R N I N G ! ! W A R N I N G ! ! W A R N I N G ! ! W A R N I N G ! !
NEVER TURN ON THE POWER IN A CONDITION IN WHICH THE
DEGAUSS COIL HAS BEEN REMOVED.
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 APPEAR AS SHOWN IN THIS MANUAL OR IN
SUPPLEMENTS PUBLISHED BY SONY. CIRCUIT ADJUSTMENTS
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!!
NE JAMAIS METTRE SOUS TENSION QUAND LA BOBINE DE
DEMAGNETISATION EST ENLEVEE.
ATTENTION AUX COMPOSANTS RELATIFS A LA
SECURITE!!
LES COMPOSANTS IDENTIFIES PAR UNE TRAME ET PAR UNE
MARQUE
¡
SUR LES SCHEMAS DE PRINCIPE, LES VUES
EXPLOSEES ET LES LISTES DE PIECES SONT D'UNE
IMPORTANCE CRITIQUE POUR LA SECURITE DU
FONCTIONNEMENT. NE LES REMPLACER QUE PAR DES
COMPOSANTS SONY DONT LE NUMERO DE PIECE EST
INDIQUE DANS LE PRESENT MANUEL OU DANS DES SUPPLE-
MENTS PUBLIES PAR SONY. LES REGLAGES DE CIRCUIT
DONT L'IMPORTANCE EST CRITIQUE POUR LA
SECURITE DU FONCTIONNEMENT SONT IDENTIFIES DANS
LE PRESENT MANUEL. SUIVRE CES PROCEDURES LORS DE
CHAQUE REMPLACEMENT DE COMPOSANTS CRITIQUES, OU
LORSQU'UN MAUVAIS FONTIONNEMENT SUSPECTE.
1. Check the area of your repair for unsoldered or
poorly-soldered connections. Check the entire board
s u r f a c e f o r s o l d e r s p l a s h e s a n d b r i d g e s .
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. L o o k f o r u n a u t h o r i z e d re p l a c e m e n t p a r t s ,
particularly transistors, 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 recommend 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 B+ and HV to see if they are specified
values. Make sure your instruments are accurate;
be suspicious of your HV meter if sets always have
low HV.
8. C h e c k t h e a n t e n n a t e r m i n a l s , m e t a l t r i m ,
“metallized" knobs, screws, and all other exposed
metal parts for AC Leakage. Check leakage as
described below.
1. A commercial leakage tester, such as the Simpson 229 or
RCA WT-540A. Follow the manufacturers' instructions to
use these instructions.
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's 250 and Sanwa
SH-63Trd are examples of passive VOMs that are suitable.
Nearly all battery operated digital multimeters that have a
2V AC range are suitable. (See Fig. A)