Sony tc w 455 service manual

Page 2

'l'C-W455

SAFETY CHECK-OUT (US Model)

CONTENTS
M M 111812 After correcting the original service problem,
SPECIFICATIONS ..................... I perform the following safety check before releasing
SAFETY CHECK-OUT (US Model) .......... 2 the set to the customer:
SECTION 1 OUTLINE Check the antenna terminals, metal trim, metallized
1-1. LOCATION AND FUNCTION OF knobs, screws, and all other exposed metal parts for
CONTROLS ................ 3 AC leakage, Check leakage as described below.
1-2. IC501(M50742~404)
PIN FUNCTIONS .............. 4-6 LEAKAGE TEST
SECTIONZ DISASSEMBLY ............. 7
' Th AC 1 k f sed m t 1 tt
SECTION3 ADJUSTMENTS 8 ea age mm any expo e a p O
earth ground and from all exposed metal parts to any
3-1. MECHANICAL ADJUSTMENTS ...... 8 . .
3 2 ELECTRICAL ADJUSTMEN S 9 11 exposed metal part havrng a return to chassrs, must
' T ' ' _ not exceed 0.5 mA (500 microampers) Leakage
SECTION 4 CIRCUIT BOARDS LOCATION . . 12
current can be measured by any one of three
SEMICONDUCTOR LEAD LAYOUTS ....... 12 methods
SECTION 5 DIAGRAMS '
5-1. MOUNTING DIAGRAM ........ 13-6 1. A commercial leakage tester, such as the
5_2. SCHEMATIC DIAGRAM ....... 17-21 Simpson 229 or RCA WT-540A. Follow the
SECTION 6 EXPLODED VIEWS AND manufacturers instructions to use these instru-
PARTS LIST ................ 23-27 ments-
SECTION 7 ELECTRICAL PARTS LIST - a 28-32 2. A battery-operated AC milliammeter. The Data
SECTION 8 TROUBLE SHOOTING -------- 32 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 volt-
meter. 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 VOM that
is suitable. Nearly all battery operated digital
multimeters that have a 2 V AC range are
suitable. (See Fig. A)

To Exposed Metal
Part: on Set
AC
0,75uF g 1.5m / voltmeter
(0.75 VI
3 Earth Ground
Fig A. Using an AC voltmeter to check AC leakage.