CPD-4403
SAFETY CHECK-OUT
After correcting the original service problem, perform the fol-LEAKAGE TEST
lowing safety checks before releasing the set to the customer:The AC leakage from any exposed metal part to earth ground
1. Check the area of your repair for unsoldered or poorly-sol-and from all exposed metal parts to any exposed metal part hav-
dered connections. Check the entire board surface for soldering a return to chassis, must not exceed 0.5 mA (500 microam-
splashes and bridges.peres).
2. Check the interboard wiring to ensure that no wires areLeakage current can be measured by any one of three methods.
Opinched� or contact high-wattage resistors.1. A commercial leakage tester, such as the Simpson 229 or
3. Check that all control knobs, shields, covers, ground straps,RCA WT-540A. Follow the manufacturersO instructions to
and mounting hardware have been replaced. Be absolutelyuse these instruments.
certain that you have replaced all the insulators.2. A battery-operated AC milliammeter. The Data Precision
4. Look for unauthorized replacement parts, particularly tran-245 digital multimeter is suitable for this job.
sistors, that were installed during a previous repair. Point3. Measuring the voltage drop across a resistor by means of a
them out to the customer and recommend their replacement.VOM or battery-operated AC voltmeter. The Olimit� indica-
5. Look for parts which, though functioning, show obvioustion is 0.75 V, so analog meters must have an accurate low-
signs of deterioration. Point them out to the customer andvoltage scale. The Simpson 250 and Sanwa SH-63Trd are
recommend their replacement.examples of a passive VOMs that are suitable. Nearly all
6. Check the line cords for cracks and abrasion. Recommendbattery operated digital multimeters that have a 2 V AC
the replacement of any such line cord to the customer.range are suitable. (See Fig. A)
7. Check the B+ and HV to see if they are specified values.
Make sure your instruments are accurate; be suspicious of WARNING!!
your HV meter if sets always have low HV.NEVER TURN ON THE POWER IN A CONDITION IN
WHICH THE DEGAUSS COIL HAS BEEN REMOVED.8. Check the antenna terminals, metal trim, Ometallized�
knobs, screws, and all other exposed metal parts for AC
Leakage. Check leakage as described below.SAFETY-RELATED COMPONENT WARNING!!
COMPONENTS IDENTIFIED BY SHADING AND MARK
! ON THE SCHEMATIC DIAGRAMS, EXPLODEDTo Exposed Metal
Parts on SetVIEWS 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-
ACMENTS THAT ARE CRITICAL FOR SAFE OPERATION
0.15 ?F1.5 k&VoltmeterARE IDENTIFIED IN THIS MANUAL. FOLLOW THESE
(0.75 V)
PROCEDURES WHENEVER CRITICAL COMPONENTS
ARE REPLACED OR IMPROPER OPERATION IS SUS-
PECTED.
Earth Ground
Fig. A. Using an AC voltmeter to check AC leakage.
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ACEC
