Sony tc rx 420 service manual

Page 1

SERVICE MANUAL

US Model
Canadian Mode/

Dolby noise reduction manufactured under license from
Dolby Laboratories Licensing Corporation.
DOLBY" and the double-D symbol DU are trademarks of
Dolby Laboratories Licensing Corporation.

SPECIFICATIONS
Ft d' 4t k 2 h l t Model Name Using Similar Mechanism Tc-WR620
ecor mg sys em »rac »c anne sereo _
Fast winding Approx. 90 sec. (with 0-60 cassette) Tape Transport Mechanism Type TCM'190R312
Bias AC Bias
Signal-tonoise ratio (NAB, at peak level) Outputs
DOLBY NR button OFF B-TYPE C-TYPE Line outputs Output level 0.44 V (-5 dB) at
Cassette ON ON (phono jacks) a load impedance
Type IV (Sony METAL-ES) 58dB 65dB 71dB 0 47k Ohms
Type ll (Sony UX-S) 57 dB 64 dB 70 dB Load Impedance over 10k ohms
Headphones Output level -28 dB at a load
Type I (80W HRS) 54dB 61dB 67dB output (stereo impedance of 8
phone jack) ohms
Total harmonic distortion
1.0 % (with Sony MEI'AL»ES cassettes)
General

Frequency response (DOLBY NR OFF)

Type IV cassette 20-16000 HZ (:3 (13)
(Sony MEFALES) 30-15900 Hz (:3 dB, OVU recording)

Type II cassette 20-16900 Hz (:3 dB)

(Sony UX-S) (SO-15,000 Hz
Type | cassette 25-15000 Hz (:3 dB)
(Sony HF-S) 30-14000 Hz

Wow and flutter 0.09% WRMS (NAB)

lnputs

l Microphone inputs Sensitivity 025 mV (-70 dB)

I (phone jacks)

For a low-impedance microphone

| Line inputs Sensitivity 77.5 mV (-20 dB)

(phono jacks)

Input impedance 50k ohms

Power requirements
120 V AC, 60 Hz
Power consumption
22 W
Dimensions Approx. 430 x 123 x 295 mm (w/h/d)
(17 x 47/8 x115/3 inches)
including projecting parts and controls
Weight Approx. 4.0 kg (8 lbs 13 oz)
Supplied accessory

Connecting cord (2)

Design and specifications are subject to change without
notice.

STEREll CASSETTE DECK
S 0 NY;

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TC-RX420

MODEL IDENTIFICATION
-Specification Label-

SONYw

STER E0 CASSETTE DECK

WWW

MODEL Nor TORX420

SERIAL No.
MADE IN JAPAN

US, Canadian MODEL: AC 120 60H: 22W

SAFETY CHECK-OUT

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 {or

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 In chassis. must

not exceed 0.5mA (500 microarnpers). Leakage
current can he measured by any one of three
methods.

1 /\ commercial leakage tester, such as the

Simpson 229 or RCA \V'I-S4()A l-ollow the
manufacturers' instructions to use these instr'u»

merits

SAFETY-RELATED GOMPONENT WARNING! !

COMPONENTS IDENTIFIED BY MARK & 0R 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.

.._2

A battery-operated AC milliammcler, l'hel)a1:r
lreorsion 245 digital multimeter is suitable for
this job.

3. Measuring the voltage drop across a resistor by

means of a VOM or haltery~operated A( volt-
'lhe limit" indication rs ().75V. 30
analog meters must have an accurate low-
voltage scale. The Simpson 250 and Sanwa
SII63'IrtI are examples of a passive VOM that

meter.

is suitable. Nearly all battery operated digital
multimeters that haw a ZV Al range are
suitable. (See Fig. Al

I» To Exposed Mela/

I Pam on Set

I

r r

I I

I _

; r"t

. _1_ 4 .Ac

0.75uF I 5km ITT/ vo/rmerm

a T ,

i

4

faith Ground

Fig, ,4. Using an AC vo/zmeter to check AC leakage

ATTENTION AU COMPOSANT AYANT RAPPORT
A LA SECURITE!

LEs COMPOSANTS IDENTIFrEs PAR UNE MARQUE A
sun LEs DIAGRAMMES SCHEMATIOUES ET LA LISTE
DES PIECES SONT CRITIQUES POUR LA sEcuané
DE FONCTIONNEMENT. NE REMPLACER CES COM-
POSANTS QUE PAR DES PIECES 'SONY DONT LES
NUMERos SONT DONNEs DANS CE MANUEL 0U
DANS LEs SUPPLEMENTS PUBLIES PAR SONY.