Onkyo DX 750 Service Manual

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Ref. No. 3466
ONKYO® SERVICE MANUAL
M O D EL DX-750
Black model
BMP 230V AC, SOHz
B Mw 120/220v AC, 50/60Hz
SAFETY-RELATED COMPONENT WARNING! ! SPECIFICATIONS
COMPONENTS IDENTIFIED BY MARK A ON THE Sign-31 readout system: Optical non-contact
SCHEMATIC DIAGRAM AND IN THE PARTS LIST ARE Reading rotation: About 500,- 200mm-
CRITICAL FOR RISK OF FIRE AND ELECTRIC SHOCK. Linear velocity (lcgfiajflfiw mm
REPLACE THESE COMPONENTS WITH ONKYO PARTS Error correction system: Cross Interleave Reed Solomon code
WHOSE PARTS NUMBERS APPEAR AS SHOWN IN THIS WA converter: 1 bit PWM ACCWULSE WA CON,
MANUAL. VERTER
Sampling frequency: 352.8 kHz
MAKE LEAKAGE-CURRENT 0R RESISTANCE MEA- (Eighvfimes oversampling)
SUREMENTS To DETERMINE THAT EXPOSED PARTS NumberofchanneSj 2 (stereo)
ARE ACCEPTABLY INSULATED FROM THE SUPPLY WWW 55.?0155- , _ 5 HZ 20 2
IRCUIT BEFORE RETURNING THE APPLIANCE To Total mm dsmnon' 04% (at 1 kHz)
C * DynamIc range: 96 dB
THE CUSTOMER. Signal to noise ratio: l00 dB
Channel separation: 90 dB (at 1 kHz)
Wow and Flutter: Below threshold of measurability
Output level: 2 volts r.m.s.
Power consumption: 1 1 watts
Dimensions (W x H X D): 455 X 120 x 308 mm
Weight: 5.1kg, .2 lbs.

Specifications and external appearance are subject to change with-
out notice because of product improvements.

ONKYO
Alllllfl BflMPflNENlS

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' tax-75o

TABLE OF CONTENTS

Specifications,,..,..

Service procedures...

Caution on replacement of optical pickup...,...e....

Protection of eyes from laser beam during servicing
Laser warninglabels,..,.......,.............. .. .
Exploded view.
Parts list ........
Mechanismrexploded view ........................................................................

Utbb-JWN

10

Removement of tray ass.......,....,.y

Microprocessor connection diagram

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Microprocessor terminal description..,...........t.

lC block diagrams and descriptions

Disassembling procedures

Block diagram

Adjustment procedures
Printed circuit board view from bortom side.

Schematic diagram
Printed circuit boardparts list...,._r....

k..
Packing View

Schematic diagram mechanism bloc

SERVICE PROCEDURES

1. Safety-check out
After canceling the original service problemperform
the following safety check before releasing the set
to the customer:
Connect the insulating-resistance tester between the
plug of power supply cord and chassis.
SpecificationszMore than lOMohm at 500V,

2. Voltage Selector (Back panel)
Worldwide models are equipped with a voltage selector
to conform with local power supplies.Be sure to set
this switch to match the voltage of the power supply
in user's area before turning the power switch on.
Voltage is changed by sliding the groove in the switch
with a screw driver to the right or left.
Confirm that the switch has been moved all the way to
the right or left before turning the power switch on.

[II] [H]
4 P P
220v ~ 120v ~ 220v ~ 120v ~
at ACIZOV at AC220V

CAUTION ON REPLACEMENT OF OPTICAL PICKUP

The laser diode in the optical pickup block is so
sensitive to static elecuicity,surge current and etc,
that the components are liable to be broken down
or its reliability remarkably deteriorated.

PRECAUTIONS

During repair,carefulley take the following precautions.

(The following precautions are included in the service

pans.)

1.Ground for the work-desk.
Place a conductive sheet such as a sheet of copper
(with inpedance lower than 10MB) on the work-
desk and place the set on the conductive sheet so
that the chassis.

2.Grounding for the test equipment and tools.
Test equipments and toolings should be rounded
in order that their ground level is the same the
ground of the power source.

3.Gr0unding for the human body.
Be sure to put on a wrist-strap for grounding whose
other end is grounded.
Be particularly careful when the workers wear
synthetic fiber clothes, or air is dry

4.Select a soldering iron that permits no leakage and
have the tip of the iron wellagrounded.

5.Do not check the laser diode terminals with the
probe of a circuit tester or oscilloscope.