JVC XM-PX70BU, XM-PX70PN, XM-PX70WT Service Manual

XM-PX70WT/BU/PN

SERVICE MANUAL

PORTABLE MINIDISC PLAYER

XM-PX70WT/BU/PN

Area Suffix

UB					Hong Kong

Contents

Safety Precautions	1-2
Attention when
MD pick up is exchanged	1-3
Disassembly method	1-4
Adjustment method	1-9
Maintenance of laser pickup	1-10
Replacement of laser pickup	1-10
Description of major ICs	1-11
Attention when parts
are exchanged	1-24

COPYRIGHT 2001 VICTOR COMPANY OF JAPAN, LTD.

No.20897

Jan. 2001

XM-PX70WT/BU/PN

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 manufacturer`s

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 () 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.

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 a return path to the chassis, to a known

good

earth ground. Any leakage

current must not exceed 0.5mA AC (r.m.s.)

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

1,500

10W resistor paralleled by

a 0.15

F AC-type

capacitor

between an

exposed

AC VOLTMETER

metal part and a known good earth ground.

(Having 1000

Measure the

AC

voltage across the resistor

with the

ohms/volts,

AC voltmeter.

or more sensitivity)

Move the

resistor

connection

to eachexposed metal

part,

particularly

any exposed metal part having a

0.15

F

AC TYPE

return

path

to the

chassis, and meausre the AC

Place this

voltage across the

resistor. Now, reverse the plug in

probe on

the AC outlet and repeat each measurement. voltage

each exposed

1500

10W

measured Any must

not exceed 0.75 V AC

(r.m.s.).

metal part.

This

corresponds

to 0.5 mA AC (r.m.s.).

Good earth ground

1.

has been designed and manufactured to meet international

safety

standards.

This equipment

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.

!

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.

1-2

XM-PX70WT/BU/PN

Attention when MD pickup is exchanged

1. About the static electricity protection measures

The laser diode in the traverse unit (optical pick up) is easy to be destroyed by clothes and the human body to the electrified static electricity.

Please note the explosion by static electricity when repairing.

2. About the earth processing for the electrostatic destruction prevention

In the equipment which uses an optical pick up (laser diode), an optical pick up is destroyed by the static electricity of the work environment.

Please do the earth processing and work.

1) Earth of work stand

Please pull the conductive material (conductive sheet) or the iron plate to the depository place of the traverse unit (optical pick up), and take the earth to ground.

2) Human body earth

Please use the anti-static wrist strap to exhaust the electrified static electricity to the human body.

anti-static wrist strap

Conductive material (conductive sheet) or the iron plate

3.Handling the optical pick up

1)Please return according to a correct procedure based on short processing after exchanging parts.

2)Do not use a tester to check the condition of the laser diode in the optical pick up .The tester 's internal power source can easily destroy the laser diode.

4.Attention when unit is disassembled

Please refer to "Disassembling method" for how to detach .

1)Please be sure to solder before a flexible wire is removed from connector on a main printed circuit board as shown.

if you removes without soldering.the MD picking up assembly might destroy

2)When installing , solder in the part of short round should be removed after a flexible wire is connected with connector.

Solder short

1-3

XM-PX70WT/BU/PN

Disassembly method

Removing the MD door assembly

(See Fig.1 and 2)

MD door assembly

1.Shift the door lever to open the door.

2.Remove the four screws A and detach the MD door assembly from the main body.

A

Door lever

Fig.1

Removing the holder assembly

(See Fig.3 and 4)

Prior to performing the following procedure, remove the MD door assembly.

1.Turn the holder assembly as shown in Fig.3.

2.Pull the side arm (L) marked a and remove outward. Open the holder assembly as shown in Fig.4.

3.Move the marked b in the direction of the arrow and release it from the shaft.

4.Move the part c inward and pull out the holder assembly from the shaft.

ATTENTION: When reassembling, first reattach the part c to the shaft of the chassis assembly. And next, fit the “U-shaped” notch to the shaft.

MD door assembly

Door lever

A

Fig.2

Holder assembly

Part a

Side arm (L)

Holder assembly

Fig.3

“U-shaped” notch

Holder assembly

Holder assembly

Part c shaft

Part b

Part c

Fig.4

1-4

Removing the chassis assembly

(See Fig.5 to 7)

Prior to performing the following procedure, remove the MD door assembly and the holder assembly.

1.Open the battery lid. Release the tab d and pull out the battery lid.

2.Remove the screw B and pull out the side arm (R) upward.

3.Remove the two screws C and pull out the eject unit.

4.Remove the screw D, E, F, G and H attaching the chassis assembly respectively.

5.Disengage the three joints e of the bottom case and the battery holder. Remove the chassis assembly and the jack cover at once.

XM-PX70WT/BU/PN

Chassis assembly

Side arm (R)

Tab d

Joint e

D

B

Joint e

Battery lid

Fig.5

Battery lid

Eject unit

C

C

Chassis assembly

Fig.6

E

Chassis assembly

Joint e

H

Joint e
Bottom case	F	G

Battery holder

Fig.7

1-5

XM-PX70WT/BU/PN

	Removing the main board and the		Battery holder
	battery holder (See Fig.8 and 9)	CN401
		Soldering f
	Prior to performing the following procedures, remove	CN301
	the MD door assembly, the holder assembly and the
	chassis assembly.

ATTENTION: Before disconnecting the flexible wire extending from the pickup, make sure to solder the short circuit round to prevent

damage to the pickup.

Short circuit round

1.Solder the short circuit round of the flexible wire on the main board.

I

2.Disconnect the flexible wires from connector CN301 and CN401 on the main board.

3.Remove the one screw I attaching the main board. Remove the main board with the battery holder .

4.Unsolder the four soldered parts f retaining the main board and the battery holder.

ATTENTION: When reassembling, connect the flexible wire extending from the pickup to the connector on the main board and unsolder the short circuit round.

Headphone jack assembly	Soldering f
Main board
Fig.8
Short circuit round	CN401

CN301

Fig.9

Removing the headphone jack assembly (See Fig.10)

Prior to performing the following procedures, remove the MD door assembly, the holder assembly, chassis assembly and the main board.

1.Disconnect the flexible wire extending from the headphone jack from connector CN601 on the main board.

Battery holder

CN601

Headphone jack assembly

Main board

Fig.10

1-6

<Removal of the MD

mechanism section>

Prior to performing the following procedures, remove the MD door assembly, the holder assembly, the chassis assembly and the main board.

Removing the spindle motor

(See Fig.11)

1.Unsolder the part g on the flexible wire extending from the underside of the chassis assembly to the spindle motor.

ATTENTION: Do not spill flux on the gear and others.

Chassis assembly

Lead screw

Part i

Pickup unit

Part h

Spindle motor

2. Remove the three screws J attaching the spindle
motor.	Fig.11

Removing the pickup unit (See Fig.11)

ATTENTION: When handling the pickup unit, touch the parts marked in Fig.13 only.

1.Remove the slit washer and the worm gear from the underside of the chassis assembly.

2.Remove the screw K attaching the shaft holder and draw out the shaft (lead screw).

3.Pull out the pickup unit and the lead screw while disengaging the part h and i.

Lead screw

Lead spring

Fig.12

XM-PX70WT/BU/PN

Worm gear

Slit washer

K

Shaft holder

Part g

J

L

Pickup

Removing the pickup (See Fig.12 and 13)

Touch these parts only.

ATTENTION: When handling the pickup unit, touch the parts marked in Fig.13 only.

1.Remove the screw L and the lead spring.

2.Pull out the shaft from the pickup.

Fig.13

1-7

XM-PX70WT/BU/PN

Removing the feed motor (See Fig.14)

j

1.Peel off the adhesive tape j on the flexible wire on the underside of the feed motor.

2.Unsolder soldering k connecting the flexible wire to the feed motor.

3.Remove the two screws M attaching the feed motor.

Feed motor

ATTENTION: When reassembling, reattach the flexible wire with an adhesive tape and solder.

M

Soldering k

M

Chassis assembly	Pickup unit

Fig.14

1-8