Sony cfs 720 service manual

Page 1

[IFS-720

SERVICE MANUAL us Model

Canadian Model
E Model

MEGABASS

Model Name Using Similar

Mechanism CF37)

Tape Transport deck A MF-730PB-780

Mechanism Type deck B MF-710RP-75D
SPECIFICATIONS

AUDIO POWER SPECIFICATIONS

POWER OUTPUT AND TOTAL HARMONIC DISTORTION

With 6 ohms loads, both channels driven from 70 - 15,000 Hz; rated 5 watts per channel
minimum RMS power, with no more than 10% total harmonic distortion in AC operation.

OTHER SPECIFICATIONS Battery life Batteries FM recording
Frequency range in 22.06 : 12:) 11:12 233.?mrsfuper Approx. 5.5 hours
Antennas FM: Telescopic antenna

Recording system fixaflrgfhfngtj :tzrreo :igirfiaw (N) Approx. 11 hours
2:21:23 response gilltrahogg??::m (43/. inches) dia. x 2 Dimensions Approx. 681 x 215 x225 mm (w/h/d)

(267/. x evzxev. inches)
not incl. projecting parts and controls
Weight Approx. 6.5 kg (14 lb 5 oz) incL batteries
Accessory supplied AC power cord (1)

Power outputs (Canadian model)
Full-range speakers: 5W + SW
(at 10% harmonic distortion) in DC operation
Inputs MIX MtC input jack (mono miniiack) (1)
sensitivity 3.9mV (or low impedance Demgn and specifications subject to change without notice
microphone
CD/LlNE IN jack (stereo phone) (2) input
impedance 50 kilohms, sensitivity 0.43V
Outputs Headphones jack (stereo miniiack) (or
16 - 58 ohm impedance headphones
Power requirements 120V AC. 50 Hz
9V DC. six size D (R20) batteries

RADIU CASSETTE-BBRDER
S O N Y;

Page 2

CFS-720

TABLE OF CONTENTS

Section Title Page
1. GENERAL

1-1. Location and Function of Controls .............. 3
2. DISASSEMBLY

2-1. Removal of Cassette Lid Assy .................. 4
3. MECHANICAL ADJUSTMENTS .................... 5
4. ELECTRICAL ADJUSTMENTS

4-1. Tape Recorder Section ........................ 6

4-2. Radio Section .................................. 8
5. DIAGRAMS

5-1. Semiconductor Lead Layouts .................. 10

SAFETY

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.

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 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-54OA. Follow the
manufacturers instructions to use these instru-
ments.

A' battery-operated AC milliammeter. The Data
Precision 245 digital multimeter is suitable for
this job.

SAFETY-RELATED COMPONENT WARNING

COMPONENTS IDENTIFIED 8V MARK A OR DOTTED
LINE WITH MARK A 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 PUB-
LISHED BY SONY.

Section Title Page
5-2. Printed Wiring Boards ........................ 11
5-3. Schematic Diagram -Tuner Section-. . . . . . . .15
5-4. Schematic Diagrams Audio Section- .. . . 19

6. EXPLODED VIEWS
6-1. Cabinet (Rear), Speaker Section ................ 22
6-2. Cabinet (Front) Section ........................ 23
6-3. Deck A mechanism Section (1) ................ 24
6-4. Deck A mechanism Section (2) ................ 25
6-5. Deck A mechanism Section (3) ................ 26
6-6. Deck B mechanism Section (1) . . . .27
6-7. Deck B mechanism Section (2) . .28

7. ELECTRICAL PARTS LIST ...................... 29

CH ECK-OUT

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 2V AC range are
suitable. (See Fig. A)

To Exposed Metal
Parts on Set

L_.
0.15,.F 1.5m
L /

._l

A C
voltmeter
(0. 75 V)

Earth Ground

Fig. A. Using an AC voltmeter to check AC leakage.

ATTENTION AU COMPOSANT AVANT RAPPORT
A LA SECURITE!

LES COMPOSANTS IDENTIFIES PAR UNE MAROUE A
son LES DIAGRAMMES SCHEMATIOUES er LA LlsTE
DES PIECES sour camouss POUR LA sécURIré
DE FONCTIONNEMENT. NE REMPLACER CES COM-
POSANTS qua PAR DES PlECEs sonv oom LES
NUMénos som DONNES DANS cs MANUEL ou
DANS LES SUPPLEMENTS Pusués PAH souv.