Table Of Contents - Sony TA-AV571 Service Manual

SAFETY CHECK-OUT
After correcting the original service problem, perform the follow-
ing safety checks before releasing the set to the customer:
Check the antenna terminals, metal trim, "metallized" knobs, screws,
and all other exposed metal parts for AC leakage. Check leakage as
described below.
LEAKAGE
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). Leak-
age 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 pas-
sive VOM that is suitable. Nearly all battery operated digital
multimeters that have a 2V AC range are suitable. (See Fig. A)
To Exposed Metal
Parts on Set
0.15µF
Fig. A. Using an AC voltmeter to check AC leakage.
AC
1.5k Ω
voltmeter
(0.75V)
Earth Ground

TABLE OF CONTENTS

1. SERVICING NOTE
2. GENERAL
.......................................................................... 4
3. DIAGRAMS
3-1. Circuit Boards Location ........................................................ 5
3-2. Waveforms ........................................................................... 6
3-3. Schematic Diagram - Main Section - .............................. 7
3-4. Printed Wiring Board - Main Section - .......................... 11
3-5. Printed Wiring Board - Power Section - ........................ 13
3-6. Printed Wiring Board - Display Section - ...................... 15
3-7. Schematic Diagram - Display Section - ........................ 17
3-8. IC Block Diagrams ............................................................. 19
3-9. IC Pin Function
• IC401 µPD78042FGF-036-3BP (RF System Control) .... 21
4. EXPLODED VIEWS
4-1. Case and Back Panel Section .............................................. 23
4-2. Front Panel Section ............................................................. 24
4-3. Chassis Section ................................................................... 25
5. ELECTRICAL PARTS LIST
SAFETY-RELATED COMPONENT WARNING !!
COMPONENTS IDENTIFIED BY MARK ! OR DOTTED LINE
WITH MARK ! ON THE SCHEMATIC DIAGRAMS AND IN
THE PARTS LIST ARE CRITICAL TO SAFE OPERATION.
REPLACE THESE COMPONENTS WITH SONY PARTS
WHOSE PART NUMBERS APPEAR AS SHOWN IN THIS
MANUAL OR IN SUPPLEMENTS PUBLISHED BY SONY.
- 2 -
.......................................................... 3
........................................ 26