Technics RSB 755 Service Manual

Page 1

ORDER NO. AD590826005

ervice Manual

Dolby NR-Equipped
Stereo Cassette Deck

DEI-

* HX Pro headroom extension originated by Bang
Olufsen and manufactured under license from Dolby
Laboratories Licensing Corporation.

DOLBY, the double-D symbol, and HX PRO" are

trademarks oi Dolby Laboratories Licensing

Corporation.

MECHANISM SERIES: AR350

Cassette Deck

RS-B755

Color

Area

02:22? Area Color
(P) USA.

(PC) Canada.

(E. E5) Continental Europe. (K)
(EB) Great Britain.

(EG) F.R. Germany and Italy

l SPECIFICATIONS
I CASSETTE DECK SECTION
Deck system Stereo cassette deck Wow and flutter 0.05% (WRMS)
Track system 4-track, 2-channel i0.14% (DIN)
Heads Fast Iorward and rewind times
Record Permalloy (Combination) Approx. 90 seconds with 0-60 cassette tape
Playback Permalloy (Combination) input sensitivity and impedance
Erasure Double-gap ferrite LINE 60 mV/47 kn
Motors Output voltage and impedance
Capstan drive Quartz DD motor LINE 400 mV/SOOQ
Reel table drive DC motor HEADPHONES 125 mV/BQ
Cassette holder open/close DC motor (BQ~6000)
Recording system AC bias
Bias irequency 80 kHz
Erasing system AC erase I GENERAL
Tape speed 4,8 cm/sec. (17/a ips) Power consumption 21 W
Frequency response Power supply
NORMAL 20 Hz~ 19 kHz For U.S.A. and Canada AC 120 V, 60 Hz
20 Hz~18 kHz (DIN) For Great Britain AC 240V, 50/60 Hz
CIO: 20 Hz~20 kHz For others AC 220 V. 50/60 Hz
20 Hz~19 kHz (DIN) Dimensions (WXHXD) 430x135x290 mm
METAL 2t) Hz~21 kHz (165/15"X 5/e"><113/32)
20 Hz~20 kHz (DIN) Weight 5.3 kg (11 .7 |b,)
SIN (signal levelzmax recording level. CrOz type tape)
DoibyC NR on 74 dB(CC|R) Note:
Dolby B MB on 66 dB (CCIR) Specifications are subject to change without notice.
Dolby NR ott 57 dB (A weighted) Weight and dimensions are approximate.
Menuhin Services Company Pennant: Sam Company, Mntsushlu Electric at Canada Limited
Division of Mouulhiia Electric Diviclon or mun-rm- Electric 5770 Ambler owe. Mississauga. Ontario.
CorpemIon of America at Puma Rico, Inc. LAW 273

Technics

50 Maadomiand Parkway,
Secaucus. New Jersey 07094 65th Infantry Ava. Km.9 5

San Gabriel lndustrlai Park
Carolina. PR. 00630

Matlushlt- Electric Induotrlal
00.. Ltd.

Central PO Box 288.

Osaka 53091.Japan

Page 2

RSBYSS

. CONTENTS

SAFETY PRECAUTION
ACCESSORIES ...........
FRONT PANEL CONTROLS AND FUNCTIONS
CONNECTIONS...
RECORDING WITH HIGH T N
DISASSEMBLY INSTRUCTIONS ..............
MEASUREMENT AND ADJUSTMENT METHODES.
TERMINAL FUNCTION OF ICS.
BLOCK DIAGRAM ....................
INTERNAL CONNECTION OF FL .
SCHEMATIC DIAGRAM ..............
TROUBLESHOOTING 0F DIRECT DRIVE MOTO .

PRINTED CIRCUIT BOARDS ......
WIRING CONNECTION DIAGRAM
REPLACEMENT PARTS Lls
EXPLODED VIEWS
REPLACEMENT PA .
RESISTORS a CAPACITORS.
TERMINAL GUIDE IC'S, TRANSISTORS AND DIODES ..... 46

>2< TECHCNICAL INFORMATION

X This technical information is located on pp 45-51 of the
RS-B555 Service Manual (Order No. AD890723105).
Therefore, refer to that Service Manual.

I SAFETY PRECAUT'ON (This "safety precaution" is applied only in USA.)

UbQN-e

o INSULATION RESISTANCE TEST

, Before servicing, unplug the power cord to prevent an electric shock.

. When replacing parts, use only manufacturers recommended components for safety.

. Check the condition of the power cord. Replace if wear or damage is evident.

. After servicing, be sure to restore the lead dress, insulation barriers, insulation papers, shields, etc

. Before returning the serviced equipment to the customer, be sure to make the following insulation resistance test to
prevent the customer from being exposed to a shock hazard.

l. Unplug the power cord and short the two prongs of the plug with a jumper wire.

2. Turn on the power switch,

3, Measure the resistance value with ohmmeter between the jumpered AC plug and each exposed metal cabinet part, such as

screwheads antenna, control shafts, handle brackets, etc.

Equtpment wrth antenna terminals should read between 3M9

and 5.2MQ to all exposed parts. (Fig, A) Equipment without antenna terminals should read approximately infinity to

all exposed parts, (Fig. 8)

Note: Some exposed parts may be isolated from the chassis by design, These will read infinity

Antenna
terminal \

Exposed
metal
part

Ohrnmeter

(FigrA)

Resistance = 3MQ-5t2MQ

Exposed 9
metal
part
Ohmmeter
(Fig 8)

Resistance = Approx 00

4. If the measurement is outside the specified limits, there is a possibility of a shock hazard. The equipment should be
repaired and rechecked before it is returned to the customer.

I ACCESSORIES
0 Stereo connection cables .................................................... 2 - AC power supply cord ...............................
[SJP2249-3] SFDACOSEOS: (E, E5, E6)
SJA172: (PC)
SJA172-1: (P)

SJA193«1: (EB)