Technics RSB 905 Service Manual

Page 1

ORDER NO. HADB705124CO

Service Manual

>i¢i<
dbx/Closed Loop Dual Capstan
DOUBLE DOLBY SYSTEM

at:

DC] DOLBY B-C NR Hx PRO

SPECIFICATIONS
Deck system Stereo cassette deck
Track system detrack, 2-cnannel
Heads
REC/PLAY Combination head
Erasing Doublegap ferrite head
Motors
Capstan Electronically controlled DC motor
Reel table drive Electronically controlled DC motor
Recording system AC bias
Bias frequency 85 kHz
Erasing system AC erase
Tape speed 4.8 cm/sec (1-7/8 ips)
Frequency response
METAL 20 Hz~22 kHz (£15 dB)
30 Hz~21 kHz (DIN)
Cr02 20 Hz~2l kHz (i153 dB)
30 Hz~20 kHz (DIN)
NORMAL 20 HZ~20 kHz (:15 dB)
30 Hz~19 kHz (DIN)
Dynamic Range (with dbx on) 110 dB (1 kHz)
Max. Input level improvement (with dbx on) 10 dB
5/ (Signal level : max recording level, 00; type tape)
dbx on 92 d8 (A weighted)
Dolby C NR on 75 dB (CCIR)
Dolby B NR on 67 dB (CCIR)
NR 0" 57 (18 (A weighted)

Motsusnltn Sowices Company Pnnnoonic Haw-Ii. Inc.
50 Meadowland Parkway,

Cassette Deck

IRS-8905

Color
(K)...Black Type

00'" Areas
(K)
(K)
(K) [E]..... ..... All European

areas except

United Kindom.
(K) ...United Kingdom.
(K) F.R.Germany.
(K) Holland.
(K) Asia, Latin

America, Middle
Nea- East, Africa
and Oceania.

(K) [XL] ........ Australia.

(K) [XB] ....... Saudi Arabia.

0,04% (WRMS)
:Ot12% (DIN)

Wow and flutter

Fast Forward and Rewind Time
Approx. 95 seconds with C-iO cassette tape
input sensitivity and impedance

LINE 60 mV/47 k0
Output voltage and impedance

LINE 400 mV/2.2 k0

HEADPHONES 125 mV/B Q
I GENERAL
Power consumption 25W

Power supply
For USA. and Canada A0 60 Hz. 120V
For continental Europe AC 5091/6on, 220v
For United Kingdom and other area
AC 50HzI60Hz, novr12w/220Vl240V
Dimensions (w x H x D) 430x 25 x 1095mm
(16»15/16 x11-732 x4-5I16)
Weight 5kg (11 lb.)
:0: HX Pro headroom extension originated by Bar; Olufse" and
manufactured under license from Dolby Laboratories
Licensing Corporation.
DOLBV, the doubie~D symbol. and Hi PRO: are
trademarks oi Dolby Laboratories Licensing brpmamm
M The term dbx is a registered trademark oi db inc-
- Specifications are subject to change withoutnotice-
Weight and dimensions are approximate

Matsuamu Enrlc Tr. dlw 00.. Ltd.
SL236, Kauni St. Ewa Beach Po. Box 288, lgnt ral osnka Japan

Secaucus, New Jersey 0709 PO. Box 774

Technics

Honolulu, Hawaii 9660343774

Pannonic Solo. Compony,
Divlolon oi Mitoushltl Eloclrlc Mittuihill Eioclrtr:
ot Pulrlu Rico, Inc.
Avst 65 De Inianteria, KM 9.7 5770 Ambler Drive, Mississauga,
Victoria Industrial Park

at Can-d: Limltod

Ontario, LAW 2T3

Carolina, Fuertu Rico 00630

Page 2

I CONTENTS
Page

I Safety Precautlon ............................................................. 2
Accessories ..............
Location of Controls
Technical Guides.
Disassenbly Instructions.
Measurement and Adiustment Methodes.
Microcomputer Terminal Function and

Waveform ................ ..
Resistors 8. Capacitors.
Terminal Guide of lCS, Transistors and Diodes ........ 18

Wiring Connection Diagram.
Printed Circuit Boards
Block Diagram ...........
Replacement Parts List
Cabinet Parts Location
Schematic Diagram ..
Replacement Parts List
Mechanical Parts Location
Description of FL Panel .....

I SAFETY PRECAUTION (This safety precaution" is applied only in U.S.A.)

mews):-

O INSULATION RESISTANCE TEST

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

When replacing parts, use only manufacturer's 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, Equipment with antenna terminals should read between 3M!)
and 5.2MS'2 to all exposed parts. (Fig. A) Equipment without antenna terminals should read approximately infinity to
all exposed parts, (Fig. B)

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

4.

Antenna
terminal \

Exposed Exposed
metal metal
part part

Ohmmeter Ohmmeter

(FieA) (Fig.8)

Resistance: 3M9-5.2 MQ Resistance =Approx 00

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

I ACCESSORIES

0 AC power supply cord...1 - Stereo connectiont..2 (SJP2264)

(sumac-[M]
SFDAcoseos-[e EG. EH]
SFDACOsaoz-[EK]
SJA173-[XL]
SJAise-IXA]
SJA183-[XB])

- AC plug adaptor...1 (SJP9215-[XA, XB])