Features; Safety Check-Out; Leakage Test; Table Of Contents - Sony TA-N77ES Service Manual

Stereo power amplifier
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TA.N77ES
TABLE OF CONTENTS
Section
Title
Specifications
. .
Model Identification
Features
Safety Check-out
.
System Connections
Function of Controls
1.
DISASSEMBLY
Circuit Boards Location
2 .
E L E C T R I C A L A D J U S T M E N Ï S .
3 .
D I A G R A M S
3-1. Semiconductor Lead Layouts
3-2. Mounting Diagram
3-3. Schematic Diagram
4 .
E X P L O D E D V I E W S A N D
PARTS LIST .
Super legalo linear system
This unit employs super legato linear system which drives
low impedance speakers and assures powerful reproduction
without low crossover distortion and switching distortion
over the wide range.
Spontaneous twin drive power supply clrcuit
Condensers having large capacity are used for the voltage
amplification drive stage of class A and power output stage
of class B. Thus, a stable output and high quality sound are
obtained, resulting in exclusion of power interferences. The
class A stage realizes a stable operation free from
interference of the power stage even when an
instantaneous or strong output is received.
G chassls
A onepiece, hard chassis, named "Gibraltar", reduces
distortion caused by vibrations.
This reduces air vibrations from the floor and speakers and
also reduces vibrations caused by the power translormer
and power transistors.
Pege
I
2
5
4
5
9
l l
t 2
l 7
2 l
5 .
E L E C T R I C A L P A R T S L I S T . .
2 5
Troubleshooting Guide
30
S A F E T Y C H E C K . O U T
After
correcting
the original
service problem,
perform the following
safety check 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.
L E A K A G E T E S T
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
methods.
I .
A
commercial leakage tester, such as the
Simpson 229 or RCA WT-540A.
Follow the
manufacturers' instructions to use these instru-
ments.
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 volt-
meter.
The "limit"
indication is 0.75V. 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 Metel
Parts on Set
0.1 5 ttF
Fig. A.
tJsing an AC voltmeter to check AC leakage.
- 3-

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