JVC JX-S555 Service Manual

SERVICE MANUAL

AV SELECTOR

JX-S555 (J)

JX-S555(J)JX-S555(J)

Contents

Safety Precautions ............................... 2

Main Parts Locations ............................ 3

Disassembly of Parts ............................ 4

Connection Diagram ............................. 6

Circuit Description ................................ 7

Design and specifications are subject to change without notice.

Adjustments ......................................... 11

Position of ICs and Adjustment Points

Servicing Guidelines ............................ 13

Block View Inside IC ............................. 17

....... 12

No.70251

Mar. 2001

JX-S555(J)

1. This design of this product contains special hardware and many circuits and components specially

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

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

Safety Precautions

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.

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.

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 metal part and a known good earth ground. Measure the AC voltage across the resistor with the AC voltmeter. Move the resistor connection to eachexposed metal part, particularly any exposed metal part having a return path to the chassis, and meausre the AC voltage across the resistor. Now, reverse the plug in the AC outlet and repeat each measurement. voltage measured Any must not exceed 0.75 V AC (r.m.s.). This corresponds to 0.5 mA AC (r.m.s.).

0.15 F AC TYPE

1500 10W

Good earth ground

AC VOLTMETER (Having 1000 ohms/volts, or more sensitivity)

Place this probe on each exposed metal part.

Warning

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.

2 (No. 70251)

Main Parts Locations

JX-S555(J)

Top cover

Jack board

MAIN board

AUDIO 2 boardAUDIO 1 board

Front panel ass'yFront 2 board

Front 1 board

Bottom chassis

Rear panel

(No. 70251) 3

JX-S555(J)

Disassembly of Parts

4 (No. 70251)

Note : For the positions of the connectors, see the connection

diagram (page 6).

JX-S555(J)

Removing the top cover

1. Remove the two screws 3 retaining the top cover 1 from the

rear panel 2, then remove the four screws 4 retaining the top cover from the side panels.

2. Slightly open out the bottoms of the side skirts I of the top

cover 1 as shown in the figure, then pull the top cover straight upward II . Do not remove the top cover by pulling it up in an oblique direction.

Removing the Audio 1 Board Board

1. Remove the top cover 1.

2. From the rear panel 2, remove the six screws 7 retaining the Audio 1 board 5 and the six screws 7 retaining the

3. Gently remove the Audio 1 board 5 and then unplug the connectors CN809 and CN810 from it.

4. Gently remove the Audio 2 board 6 and then unplug the connectors CN807 and CN808 from it.

Audio 2 board 6.

Removing the Main Board

1. Remove the top cover 1, then the Audio 1 board 5 and finally the Audio 2 board 6.

2. From the rear panel 2, remove the nineteen screws C retaining the Main board B.

3. Unplug the connectors CN1, CN3, CN804 and CN811 (and the wire from the Front Panel Assembly D )on the Main

board B .

4. Unplug the connector CN901 (in the power supply circuit) on the Main board B.

5. Remove the two clamping screws E on the Main board B.

6. Disengage the three claws of the locking card spacer F on the Main board B, then remove the Main board by lifting

it in an oblique direction.

5 and Audio 2

Removing the Rear Panel

1. Remove the top cover 1.

2. Unplug the connector CN901 (in the power supply circuit) on the Main board B.

3. Remove the twelve screws 7 retaining the Audio 1 board 5 and the Audio 2 board 6, then remove the nineteen screws

C retaining the Main board B.

4. Remove the three screws H retaining the bottom chassis G and the rear panel 2.

5. Gently remove the rear panel 2.

(Take care of the AC power cord I connected to the rear panel 2.)

Removing the Front Panel Assembly

1. Remove the top cover 1.

2. Remove the three retaining screws J from the bottom of the Front Panel Assembly D.

3. Disengage the fittings between the side panels of the Front Panel Assembly D with the bottom chassis G, then

gently pull out the Front Panel Assembly D from the bottom chassis G toward the front.

4. Unplug the connectors CN1, CN3, CN804 and CN811 from the Main board B.

5. Remove the Front Panel Assembly D.

Removing the Front 1 Board

1. Remove the top cover 1 and the Front Panel Assembly D.

2. Remove the two screws M retaining the Front 1 board K, five screws M retaining the Front 2 board L and the two screws

9 retaining the Jack board 8.

3. Remove the Front 1 board K, the Front 2 board L and the Jack board 8.

K, Front 2 Board

L and Jack Board

(No. 70251) 5

JX-S555(J)

Connection Diagram

Rear

CN809

CN810

AUDIO 1 board

CN807CN808

CN811

CN812

CN813

CN804

Front

CN805

CN806

6 (No. 70251)

AUDIO 2 board

MAIN board

CN901

CN1

CN3

CN701

CN702 CN703 CN101

Front 1 board Front 2 board Jack board

Circuit Description

1. IC2 (µPD780021ACWW01)

The µPD780021ACWW01 is a 64-pin, 8-bit single-chip microcomputer with an 8K-byte ROM and 512-byte RAM.

JX-S555(J)

Pin Name

P40/AD0

P41/AD1

P42/AD2

P43/AD3

P44/AD4

P45/AD5

P46/AD6

P47/AD7

P50/A8

P51/A9

P52/A10

P53/A11

P54/A12

P55/A13

P56/A14

P57/A15

Vss

VDD0

P30

P31

Pin No.

I/O

—

I/O

Function

Key scan inputs.

Key scan outputs.

Scan signal outputs for LED lighting.

Dubbing lock ON/OFF. H = ON. L = OFF.

Scan signal outputs for LED lighting.

CH1 INHIBIT ON/OFF. H = ON. L = OFF.

Not used.

Port grounding potential.

Port positive potential.

CH2 INHIBIT ON/OFF. H = ON. L = OFF.

CH3 INHIBIT ON/OFF. H = ON. L = OFF.

(No. 70251) 7

+ 14 hidden pages