Safety Check-Out - Sony KLV-B20G10 Service Manual

KLV-B15G10/B20G10
RM-Y1108

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.
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 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 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" indication 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 battery operated digital
multimeters that have a 2 V AC range are suitable. (See Fig. A)
To Exposed Metal
Parts on Set
0.15 µF
Fig. A. Using an AC voltmeter to check AC leakage.
AC
1.5 kΩ Voltmeter
(0.75 V)
Earth Ground
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.
– 2 –
WARNING!!