Dell D1626HT - UltraScan 1600HS - 21" CRT Display, Руководство по обслуживанию

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D1626HT
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SAFETY CHECK-OUT
(US Model only)
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 meth-
ods.
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 ex-
amples of a passive VOMs that are suitable. Nearly all battery
operated digital multimeters that have a 2 V AC range are suit-
able. (See Fig. A)
WARNING!!
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 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 COMPO-
NENTS ARE REPLACED OR IMPROPER OPERATION
IS SUSPECTED.
AVERTISSEMENT!!
NE JAMAIS METTRE SOUS TENSION QUAND LA
BOBINE DE DEMAGNETISATION EST ENLEVÉE.
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. SUIVRE CES
PROCÉDURES LORS DE CHAQUE REMPLACEMENT
DE COMPOSANTS CRITIQUES, OU LORSQU’UN
MAUVAIS FONCTIONNE-MENT EST SUSPECTÉ.
After correcting the original service problem, perform the fol-
lowing 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 transis-
tors, 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 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. Check the antenna terminals, metal trim, “metallized” knobs,
screws, and all other exposed metal parts for AC Leakage.
Check leakage as described below.
1.5 k
Ω
0.15
µ
F
AC
Voltmeter
(0.75 V)
To Exposed Metal
Parts on Set
Earth Ground
Fig. A. Using an AC voltmeter to check AC leakage.
CAUTION ON DAS (ECS) CONNECTOR
•
The connector for DAS (ECS) adjustment is provided inside the
cover shown below. Be careful with an electrical shock when
connecting the connector with the power supplied. Also, return
the removed cover to the home position.
Rear side