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Hitachi D-900BS User Manual

Hitachi D-900BS
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SERVICE
MANUAL
English
Deutsch
Frongois
No. I
O55
.
SAFETY
PRECAUTION
The following
precautions
should be observed
when servicing.
1.
Since
many
parts
in
the
unit have
special
safety.
related characteristics, always
use
genuine
Hitachi's replacdment
parts,
Especially
critical
parts
in
the
power
circuit
block
should
not be replaced with
those
of other manufacturers.
Critical
parts
are marked with
A
in the
schematic
diagram,
and
circuit board
diagram.
2.
Before
returning
a
repaired
unit to
the customer,
the service
technicían must
thoroughly test the unit to ascertain
that
it is completely safe
to operate without
danger
of electrical shock.
SicherheitsmaRnahmen
Bei
Wartungsarbeiten
sind die
folgenden
SicherheitsmaBnahmen zu
beachten:
1. Da verschiedene
Teile dieses Geràtes
Sicherheitsfunktionen
aufweisen, nur
Original-Hitachi-Ersatzteile verwenden.
Kritische
Teile
im
Netzteil
sollten nicht durch
àhnliche
Teile anderer
Hersteller
ersetzt werden. Alle kritischen
Teile
sind im
Schaltplan und im Diagramm der
Schaltplantinen mit dem
SymbolA
gekennzeichnet,
2.
Vor der
Auslieferung eines reparierten
Geràtes
an den kunden muR der Wartungstechniker
das Geràt einer
grùnd-
lichen
Prúfung
unterziehen, um
sicherzustellen,
daB
sicherer Betrieb ohne die Gefahr von
elektrischen
Schlàgen
gewàhrleistet
ist.
Précautions
de
sécu
rité
Les
précautions
suívantes doivent étre observées
à
chaque
qu'une
réparation doit étre faite.
1.
Etant
donné
que
de nombreux
composants de
I'appareil
possèdentdes
caractéristiques
relatives
à la
sécurité, utiliser
uniquement
des
pièces
de rechange
d'origine Hitachi
pour
effectuer
un remplacement. Ceci se rapporte
notamment
aux
pièces
critiques du bloc d'alimentation
qui
ne
doivent en
aucun cas
étre remplacées
par
celles d'autres fabricants.
Les
pièces
critiques
sont accompagnés du
symbole
A
dans le
schéma
de
montage et sur le
schéma
de
plaque
de
c6blage.
2. Avant de retourner
I'appareil réparé
au client, le
technicien doit
procéder
à
un essai complet
pour
s'assurer
que
l'appareil ne
présente
aucun
danger de
chocs électriques.
Note:
W
FS.....
8S.....
c......
AU
Hinweis:
W
FS.....
8S.....
c......
AU
Remarque:
General
Area
Switzerland
and Scandinavia
Great
Britain
Canada
Australia
Allgemeine Gebiete
Schweiz
und
Skandinavien
GroBbritannien
Kanada
Australien
Tous
pays
Suisse et
Scandinavie
G rande-B retagne
Canada
Australie
STEREO
CASSETTE
TAPE
DECK
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Hitachi D-900BS Specifications

General IconGeneral
Track System4-track, 2-channel stereo
Tape Speed4.76 cm/s
Total Harmonic Distortion1.0%
TypeCassette Deck
Heads1 x Record/Playback, 1 x Erase
MotorDC servo motor
Tape TypeCrO2, Metal

Summary

Safety Precautions

Technical Specifications

Disassembly Procedure

Unit Adjustments

Tape Speed Adjustment

Procedure to adjust the motor speed for correct tape transport speed.

Head Azimuth Adjustment

Aligning the playback head for optimal signal retrieval and clarity.

Playback Output and Level Meters Adjustment

Calibrating output levels and meter responses for accurate playback indication.

Source Monitor Level Adjustment

Adjusting the monitor circuit's signal level for accurate source monitoring.

Bias Trap Adjustment

Tuning the bias trap circuit to minimize unwanted signal leakage.

Bias Current and Record Level Adjustment

Setting bias current and record levels for optimal recording quality.

19kHz Trap Adjustment

Adjusting the 19kHz pilot tone trap for accurate signal processing.

Dolby NR Adjustment

Calibrating the Dolby Noise Reduction system for both recording and playback.

Mechanism Inspection

Pressure Roller Pressure Check

Measuring the pressure applied by the pressure roller to the capstan shaft.

Torque Specifications

Checking the rotational torque of the take-up and rewind mechanisms.

Back Tension Measurement

Measuring tape tension on the supply reel during rewind and playback modes.

Braking Force Check

Verifying the braking force applied to the take-up and supply reels.

Switching Time Specifications

Checking the time required for the auto-stop mechanism to engage.

Lubrication Guide

Signal Level Diagrams

Playback Signal Level Diagram

Illustrates signal levels during playback mode for various stages.

Recording Signal Level Diagram

Illustrates signal levels during recording mode for various stages.

Schematic Diagram (Amplifier Section)

Circuit Board Diagram (Amplifier Section)

Schematic Diagram (Control Section)

Circuit Board Diagram (Control Section)

Wiring Diagram

Exploded View Diagram

Replacement Parts List

Capacitors

List of capacitors used in the unit with their specifications.

Resistors

List of resistors used in the unit with their specifications.

Semi-Conductors

List of transistors, diodes, and ICs with their part numbers and specifications.

Transformers and Coils

List of transformers and coils used in the unit with their specifications.

Miscellaneous Components

List of other components like fuses, jacks, switches, and lamps with specifications.

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