Jvc MXG 70 Service Manual

Page 1

MX-G70

JVB

SERVICE MANUAL

COMPACT COMPONENT SYSTEM

MX-G70

Area Suffix

J ................... u.S.A.
C ................. Canada

[flfimapifi

DIGITAL AUDIO

SP-MXG70 CA-MXG70 SP-MXG70

Contents
Safety precautions ----------------------- 1-2 Adjustment method - 1-25
Important for laser products ------------ 1-3 Flow of functional operation
Warnings and Cautions ----------------- 1-3 until TOC read ........... 1.30
Preventing static electricity ------------- 1-4 Maintenance of laser pickup ---------- 1-31
Importance administering Replacement of laser pickup ............ 1-31

point on the safety ----- 1-5 Description of major ICs ................. 1-32
Disassembiy method --------------------- 1-6

No.20920

COPYRIGHT (C) 2001 VICTOR COMPANY OF JAPAN, LTD.

Mar. 2001

Page 2

MX-G70

-Safety Precautions

1.This design of this product contains special hardware and many circuits and components specially
for safety purposes. For continued protection, no changes should be made to the original design
unless authorized in writing by the manufacturer. Replacement parts must be identical to those
used in the original circuits. Services should be performed by qualified personnel only.

2. Alterations of the design or circuitry of the product should not be made. Any design alterations of

the product should not be made. Any design alterations or additions will void the manufacturers
warranty and will further relieve the manufacture of responsibility for personal injury or property
damage resulting therefrom.

3. Many electrical and mechanical parts in the products have special safety-related characteristics.

These characteristics are often not evident from visual inspection nor can the protection afforded
by them necessarily be obtained by using replacement components rated for higher voltage,
wattage, etc. Replacement parts which have these special safety characteristics are identified in
the Parts List of Service Manual. Electrical components having such features are identified by
shading on the schematics and by (A) on the Parts List in the Service Manual. The use of a
substitute replacement which does not have the same safety characteristics as the recommended
replacement parts shown in the Parts List of Service Manual may create shock, fire, or other
hazards.

4.The leads in the products are routed and dressed with ties, clamps, tubings, barriers and the

like to be separated from live parts, high temperature parts, moving parts and/or sharp edges
for the prevention of electric shock and fire hazard. When service is required, the original lead
routing and dress should be observed, and it should be confirmed that they have been returned
to normal, after re-assembling.

5. Leakage currnet check (Electrical shock hazard testing)

After re-assembling the product, always perform an isolation check on the exposed metal parts
of the product (antenna terminals, knobs, metal cabinet, screw heads, headphone jack, control
shafts, etc.) to be sure the product is safe to operate without danger of electrical shock.

Do not use a line isolation transformer during this check.

0 Plug the AC line cord directly into the AC outlet. Using a "Leakage Current Tester", measure
the leakage current from each exposed metal parts of the cabinet , particularly any exposed
metal part having areturn path to the chassis, to a known good earth ground. Any leakage
current must not exceed 0.5mA AC (r.m.s.)

0 Alternate check method
Plug the AC line cord directly into the AC outlet. Use an AC voltmeter having, 1,000 ohms
per volt or more sensitivity in the following manner. Connect a 1,5009 10W resistor paralleled by
a 0.15uF AC-type capacitor between an exposed

ACVOLTMETER

metal part and a known good earth ground. (Having 1000
Measure the AC voltage across the resistor with the 7 ohms/volts,
AC voltmeter. or more sensitivity)
Move the resistor connection to each exposed ° °
metal part, particularly any exposed metal part 0_15uF AC TYPE
having a return path to the chassis, and meausre _"_ Placethis
the AC voltage across the resistor. Now, reverse probeon
the plug in the AC outlet and repeat each WV " each exposed
measurement. voltage measured any must not 15009 10W metal part.
exceed 0.75V AC (r.m.s.).This corresponds to 0.5
mA AC (r.m.s.). Good earth ground

-Warnmg

1.This equipment has been designed and manufactured to meet international safety standards.

2. It is the legal responsibility of the repairer to ensure that these safety standards are maintained.
3. Repairs must be made in accordance with the relevant safety standards.

4. It is essential that safety critical components are replaced by approved parts.

5. If mains voltage selector is provided, check setting for local voltage.

1-2

A CAUTION Burrs formed during molding may be left over on some parts of the chassis. Therefore,

pay attention to such burrs in the case of preforming repair of this system.

Page 7

lRemoving the CD changer mechanism
assembly (See Fig.4 and 5)

- Prior to performing the following procedure, remove
the metal cover.

1. Disconnect the card wire from connector CN661 on
the Main board.

2. Remove the two screws C on the upper side of the
body and the two screws D on the back of the rear
panel.

3. Remove the plastic rivet attaching the main board.

4. Remove the fan connector CN705.

5. Pull both the rear panel and the front panel assembly
to the outside, then remove the CD changer

mechanism assembly by lifting the rear part of the
assembly.

CAUTION: To prevent damage to the CD fitting, be
sure to pull both the rear panel and the
front panel assembly enough to remove
the CD changer mechanism assembly.

l Removing the front panel assembly
(See Fig.6 to 10)
Prior to performing the following procedure, remove

the metal cover and CD changer mechanism
assembly.

1. Disconnect the card wires from connector CN870,
CN871 and CN315 on the main board respectively.

2. Remove the tie band and disconnect the wire from
connector CN703 on the amplifier board.

3. Disconnect the wire from connector CN220 on the
transformer board.

MX-G70

Front panel assembly

CD changer

Main board mechanism assembly

CN661

D
Plastic rivet
Front panel assembly
Fig.5
A rr Tie band Main board
mpérile;obsoard CN870
CN871
CN315
\ F
ront panel
assembly

Transformer board
CN220

Front panel assembly

Main board

Fig.7