JVC AV-27D50 Schematic

SERVICE MANUAL

COLOR TELEVISION

AV-27D502

BASIC CHASSIS

AV-27D502 AV-27D502

a SPECIFICATIONS ....................................................................................................................................2

a SAFETY PRECAUTIONS ........................................................................................................................3

a FEATURES ..............................................................................................................................................5

a MAIN DIFFERENCE LIST........................................................................................................................6

a HOW TO IDENTIFY MODELS ..................................................................................................................6

a FUNCTIONS .............................................................................................................................................7

a SPECIFIC SERVICE INSTRUCTIONS ....................................................................................................8

a SERVICE ADJUSTMENTS ....................................................................................................................12

¤ STANDARD CIRCUIT DIAGRAM (APPENDIX) .................................................................................. 2-1

a PARTS LIST ...........................................................................................................................................31

No. 51797

Mar. 2001

AV-27D502

SPECIFICATIONS

Items Contents

Dimensions (W × H × D)

················································································································································································································

Mass

TV RF System

Color Sound System

TV Receiving Channels and Frequency

VL Band

VH Band

UHF Band

CATV Receiving Channels and Frequency

Low Band

High Band

Mid Band

Super Band

Hyper Band

Ultra Band

Sub Mid Band

TV/CATV Total Channel

Intermediate Frequency

Video IF Carrier

Sound IF Carrier

Color Sub Carrier

Power Input

Power Consumption

Picture Tube

High Voltage

Speaker

Audio Power Output

Video / Audio Input (1 / 2 / 3)

29-5/8” × 23-1/4” × 19-1/2” / 75.2cm × 59.1cm × 49.4cm

71.3 Ibs/32.4kg

CCIR(M)

NTSC, BTSC System (Multi Channel Sound)

(02~06) 54MHz~88MHz

~13) 174MHz~216MHz

(07

(14

~69) 470MHz~806MHz

(02~06, A-8) by (02~06&01)

(07~13) by (07~13)

(A~1) by (14~22)

(J~W) by (23~36) (54MHz~804MHz)

(W+1~W+28) by (37~64)

(W+29~W+84) by (65~125)

(A8, A4~A1) by (01, 96~99)

180 Channels

45.75MHz

41.25MHz (4.5MHz)

3.58MHz

120V AC, 60Hz

123W

27” (68cm) Measured Diagonally

29kV±1.3kV (at zero beam current)

2” × 4-3/4” / 5 × 12cm Oval type × 2

5W × 2

Video(1,3) : 1Vp-p, 75Ø (RCA pin jack)

Audio(1,2,3) : 500mVrms ( -4dBs ), High Impedance (RCA pin jack)

S-Video ( Input 1 / 2 Over )

Y : 1Vp-p Positive (negative sync provided, when terminated with 75Ø)

C : 0.286Vp-p (burst signal, when terminated with 75Ø)

Component Input ( Input 2 )

Y : 1Vp-p positive (negative sync provided, when terminated with 75Ø)

PB/PR : 0.7Vp-p 75 Ø

—

Audio Output

(Variable)

AV Compu link EX Input

Antenna terminal

Remote Control Unit

Variable : More then 0~1550mVrms (+6dBs)

Low impedance (400Hz when modulated 100%)

3.5mm mini jack

75Ø(VHF/UHF) Terminal, F-Type Connector

RM-C301G-2A

(AA/R6/UM-3 battery × 2)

(RCA pin jack)

Design & specifications are subject to change without notice.

2 No. 51797

GOOD EARTH GROUND

0.15 µF AC-TYPE

AC VOLTMETER (HAVING 1000Ø/V, OR MORE SENSITIVITY)

PLACE THIS PROBE ON EACH EXPOSED METAL PART

1500Ø 10W

A V

This mark shows a fast

POWER CORD REPLACEMENT WARNING

Connecting thr white line side of power cord to “WHT” character side.

operating fuse, the letters indicated below show the rating.

PWB

WHT

White line side

SAFETY PRECAUTIONS

1. The design of this product contains special hardware, 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. Service should be performed by qualified personnel only.

2. Alterations of the design or circuitry of the products should not be made. Any design alterations or additions will void the manufacturer's warranty and will further relieve the manufacturer 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 Service manual. The use of a substitute replacement

which does not have the same safety characteristics as the recommended replacement part shown in the parts list of Service manual may cause shock, fire, or other hazards.

4. Use isolation transformer when hot chassis. The chassis and any sub-chassis contained in some products are connected to one side of the AC power line. An isolation transformer of adequate capacity should be inserted between the product and the AC power supply point while performing any service on some products when the HOT chassis is exposed.

5. Don't short between the LIVE side ground and ISOLATED (NEU-

TRAL) side ground or EARTH side ground when repairing.

Some model's power circuit is partly different in the GND. The difference of the GND is shown by the LIVE : ( ) side GND, the ISOLATED(NEUTRAL) : ( ) side GND and EARTH : ( ) side GND. Don't short between the LIVE side GND and ISOLATED(NEUTRAL) side GND or EARTH side GND and never measure with a measuring apparatus (oscilloscope etc.) the LIVE side GND and ISOLATED(NEUTRAL) side GND or EARTH side GND at the same time. If above note will not be kept, a fuse or any parts will be broken.

6. If any repair has been made to the chassis, it is recommended that the B1 setting should be checked or adjusted (See ADJUSTMENT OF B1 POWER SUPPLY).

7. The high voltage applied to the picture tube must conform with that specified in Service manual. Excessive high voltage can cause an increase in X-Ray emission, arcing and possible component damage, therefore operation under excessive high voltage conditions should be kept to a minimum, or should be prevented. If severe arcing occurs, remove the AC power immediately and determine the cause by visual inspection (incorrect installation, cracked or melted high voltage harness, poor soldering, etc.). To maintain the proper minimum level of soft X-Ray emission, components in the high voltage circuitry including the picture tube must be the exact replacements or alternatives approved by the manufacturer of the complete product.

8. Do not check high voltage by drawing an arc. Use a high voltage meter or a high voltage probe with a VTVM. Discharge the picture tube before attempting meter connection, by connecting a clip lead to the ground frame and connecting the other end of the lead through a 10kØ 2W resistor to the anode button.

9. When service is required, observe the original lead dress. Extra precaution should be given to assure correct lead dress in the high voltage circuit area. Where a short circuit has occurred, those components that indicate evidence of overheating should be replaced. Always use the manufacturer's replacement components.

No. 51797 3

AV-27D502

10. Isolation Check

(Safety for Electrical Shock Hazard)

After re-assembling the product, always perform an isolation check on the exposed metal parts of the cabinet (antenna terminals, video/ audio input and output terminals, Control knobs, metal cabinet, screwheads, earphone jack, control shafts, etc.) to be sure the product is safe to operate without danger of electrical shock.

(1) Dielectric Strength Test

The isolation between the AC primary circuit and all metal parts exposed to the user, particularly any exposed metal part having a return path to the chassis should withstand a voltage of 1100V AC (r.m.s.) for a period of one second.

(. . . . Withstand a voltage of 1100V AC (r.m.s.) to an appliance rated

up to 120V, and 3000V AC (r.m.s.) to an appliance rated 200V or more, for a period of one second.) This method of test requires a test equipment not generally found in the service trade.

(2) Leakage Current Check

Plug the AC line cord directly into the AC outlet (do not use a line isolation transformer during this check.). Using a “Leakage Current Tester”, measure the leakage current from each exposed metal part of the cabinet, particularly any exposed metal part having a return path to the chassis, to a known good earth ground (water pipe, etc.). Any leakage current must not exceed 0.5mA AC (r.m.s.). However, in tropical area, this must not exceed 0.2mA AC (r.m.s.).

Alternate Check Method

•

Plug the AC line cord directly into the AC outlet (do not use a line isolation transformer during this check.). Use an AC voltmeter having 1000 ohms per volt or more sensitivity in the following manner. Connect a 1500Ø 10W resistor paralleled by a 0.15µF AC-type capacitor between an exposed metal part and a known good earth ground (water pipe, etc.). Measure the AC voltage across the resistor with the AC voltmeter. Move the resistor connection to each exposed metal part, particularly any exposed metal part having a return path to the chassis, and measure the AC voltage across the resistor. Now, reverse the plug in the AC outlet and repeat each measurement. Any voltage measured must not exceed 0.75V AC (r.m.s.). This corresponds to 0.5mA AC (r.m.s.). However, in tropical area, this must not exceed 0.3V AC (r.m.s.). This corresponds to 0.2mA AC (r.m.s.).

11. High voltage hold down circuit check. After repair of the high voltage hold down circuit, this circuit shall be checked to operate correctly. See item “How to check the high voltage hold down circuit”.

AV-27D502

REPLACEMENT OF CHIP COMPONENT

CAUTIONS

1. Avoid heating for more than 3 seconds.

2. Do not rub the electrodes and the resist parts of the pattern.

3. When removing a chip part, melt the solder adequately.

4. Do not reuse a chip part after removing it.

SOLDERING IRON

1. Use a high insulation soldering iron with a thin pointed end of it.

2. A 30w soldering iron is recommended for easily removing parts.

REPLACEMENT STEPS

1. How to remove Chip parts

Resistors, capacitors, etc.

(1) As shown in the figure, push the part with tweezers and alter-

nately melt the solder at each end.

2. How to install Chip parts

Resistors, capacitors, etc.

(1) Apply solder to the pattern as indicated in the figure.

(2) Shift with tweezers and remove the chip part.

Transistors, diodes, variable resistors, etc.

(1) Apply extra solder to each lead.

SOLDER

(2) As shown in the figure, push the part with tweezers and alter-

nately melt the solder at each lead. Shift and remove the chip part.

SOLDER

(2) Grasp the chip part with tweezers and place it on the solder.

Then heat and melt the solder at both ends of the chip part.

Transistors, diodes, variable resistors, etc. (1) Apply solder to the pattern as indicated in the figure. (2) Grasp the chip part with tweezers and place it on the solder. (3) First solder lead A as indicated in the figure.

(4) Then solder leads B and C.

Note : After removing the part, remove remaining solder from the

pattern.

4 No. 51797

FEATURES

IC702

E2PROM 4k bit

IC701

MAIN MICON

IF2

SCL 1 SDA 1

SCL 0 SDA 0

AFC 2

AFC 1

Remote

control

unit

IC301

PIP

CONTROL

IC001

MTS, TONE

SURROUND CONTROL

TU001

TUNER 1

TU001

TUNER 2

IC101

1 CHIP

CONTROL

IC501

AVSW

CONTROL

Full-square CRT (cathode ray tube) reproduces fine textured pic-

•

ture in every detail. I2C bus control utilizes single chip ICs.

•

Built in Twin Tuner system.

•

Built-in HYPER-SURROUND system.

•

Built-in BBE.

•

Adoption of the Picture-In-Picture (PIP) function.

•

3 LINE DIGITAL COMB FILTER circuit improved picture quality.

•

a SYSTEM BLOCK DIAGRAM

AV-27D502

Component input terminal for talking best advantage of Component

•

Video Signal. Audio Video input terminal. (S-input ×2, V-input ×2)

•

Variable audio output terminal.

•

Closed-caption broadcasts can be viewed.

•

With AV COMPU LINK EX terminal.

•

No. 51797 5

AV-27D502

MAIN DIFFERENCE LIST

Part name

MAIN PWB SAC-1507A-M2 SAC-1506A-M2

CRT SOCKET PWB SAC-3507A-M2 SAC-3506A-M2

! PICTURE TUBE A68ADT25X01 A68QDN891X001

Model

AV-27D502/R AV-27D502/S

HOW TO IDENTIFY MODELS

The difference between AV-27D502/R and AV-27D502/S is in the PICTURE TUBE. As the result of the difference in PICTURE TUBE, the MAIN PWB also differ.

Part name

! RATING LABEL LC31139-001A-A

------------------------------------------------------------------------------------------------

Model

AV-27D502/R AV-27D502/S

INDICATED AV-27D502

INDICATED “R”

INDICATED “S”

6 No. 51797

FUNCTIONS

a FRONT PANEL

CHANNEL

OPERATE

VOLUME

POWER

AV-27D502

ON TIMER

CHANNEL

VOLUME

a FRONT PANEL DOOR OPENED

INPUT3

VIDEO

L/MONO-AUDIO-R

INPUT3 VIDEO/AUDIO TERMINAL

a REAR PANEL

POWER

a REMOTE CONTROL UNIT

(RM-C301G-2A)

CATV

VCR

CHANNEL

FREEZE

BBE

VOL

VCR CHANNEL

PREV NEXT

DVD

POWER

PIP

ON/MOVE

SWAP

INPUT

100+

VCR/DVD

POWER

VOL

RETURN+

LIGHT

V CHIP

EXIT

PIP OFF

TV/VCR

SOURCE

VIDEO STATUS

DISPLAY

SLEEP TIMER

HYPER SURROUND

RM-C301G

MUTING

PLAY FFREW

REC STOP

OPEN/CLOSE STILL/PAUSE

PAUSE

No. 51797 7

AV-27D502

SPECIFIC SERVICE INSTRUCTIONS

DISASSEMBLY PROCEDURE

REMOVING THE REAR COVER

1. Unplug the power supply cord.

2. Remove the 12 screws marked A as shown in Fig.1.

3. Withdraw the REAR COVER toward you.

[CAUTION]

When reinstalling the rear cover, carefully push it inward after in-

•

serting the MAIN PWB into the rear cover groove.

REMOVING THE CHASSIS

After removing the rear cover.

•

1. Slightly raise the both sides of the chassis by hand and remove the 3 claws marked B under the chassis from the front cabinet as shown in Fig.1.

2. Withdraw the chassis backward along the rail in the arrow direction marked C as shown in Fig.1.

(If necessary, take off the wire clamp, connector’s etc.)

When conducting a check with power supplied, be sure to confirm

that the CRT earth wire is connected to the CRT SOCKET PWB and the MAIN PWB.

REMOVING THE TERMINAL BOARD

After removing the rear cover.

•

1. Remove the 4 screws marked D as shown in Fig.1.

2. When you pull out the TERMINAL BOARD in the direction of arrow marked E as shown in Fig.1, it can be removed.

REMOVING THE SPEAKER

After removing the rear cover.

•

1. Remove the 4 screws marked K as shown in Fig.1.

2. Withdraw the speaker backward.

3. Follow the same steps when removing the other hand speaker.

CHECKING THE MAIN PW BOARD

1. To check the back side of the MAIN PW Board.

1) Pull out the chassis. (Refer to REMOVING THE CHASSIS).

2) Erect the chassis vertically so that you can easily check the back side of the MAIN PW Board.

[CAUTION]

When erecting the chassis, be careful so that there will be no con-

•

tacting with other PW Board. Before turning on power, make sure that the CRT earth wire and

•

other connectors are properly connected.

WIRE CLAMPING AND CABLE TYING

1. Be sure clamp the wire.

2. Never remove the cable tie used for tying the wires together. Should it be inadvertently removed, be sure to tie the wires with a new cable tie.

REMOVING THE FRONT CONTROL AND FRONT AV INPUT PW BOARDS

After removing the rear cover and chassis.

•

1. Remove the 3 screws marked F and the 2 screws marked J as shown in Fig.1.

2. Then remove the FRONT CONTROL PWB and FRONT AV INPUT PWB.

(If necessary, take off the wire, connector’s etc.)

REMOVING THE LF PW BOARD

After removing the rear cover and chassis.

•

1. Lift the left side of the LF PWB while pressing the 2 PWB stoppers marked G in the arrow direction marked H as shown in Fig.1.

2. Then remove the LF PWB.

(If necessary, take off the wire, connector’s etc.)

8 No. 51797

FRONT CABINET

PICTURE TUBE

SPEAKER

(x4)

CRT SOCKET PWB

FRONT AV INPUT PWB

AV-27D502

SPEAKER

REAR COVER

(x2)

CLAW

(x3)

CLAW

(x4)

FRONT CONTROL PWB

PWB STOPPER

LF PWB

PWB

STOPPER

AV SELECTOR PWB

PIP PWB

CHASSIS BASE

MAIN PWB

(x4)

(x12)

Fig.1

No. 51797 9

AV-27D502

MEMORY IC REPLACEMENT

1. Memory IC

This model use a memory IC. This memory IC stores data for proper operation of the video and deflection circuits. When replacing, be sure to use an IC containing this (initial value) data.

2. Memory IC replacement procedure

Procedure Screen display

(1) Power off

Switch off the power and disconnect the power cord from the outlet.

(2) Replace the memory IC

Initial value must be entered into the new IC.

(3) Power on

Connect the power cord to the outlet and switch on the power.

(4) System constant check and setting

1) Press SLEEP TIMER key and, while the indication of “SLEEP TIMER 0 MIN.” is being displayed, press DISPLAY key and VIDEO STATUS

key on the remote control unit simultaneously.

2) The SERVICE MENU screen of Fig.1 is displayed.

3) While the SERVICE MENU is displayed, again simultaneously press the DISPLAY and VIDEO STATUS keys to display the Fig.2 SYSTEM CONSTANT screen.

4) Refer to the SYSTEM CONSTANT table and check the setting items. Where these differ, select the setting item with the MENU UP/DOWN key and adjust the setting with the MENU LEFT/RIGHT keys. (The letters of the selected item are displayed in yellow.)

5) After adjusting, release the MENU LEFT/RIGHT key to store the setting value.

6) Press the EXIT key twice to return the normal screen.

(5) Receive channel setting

Refer to the OPERATING INSTRUCTIONS(USER'S GUIDE) and set the receive channels (Channels Preset) as described.

(6) User settings

Check the user setting items according to Table 2. Where these do not agree, refer to the OPERATING INSTRUCTIONS (USER'S GUIDE) and set the items as described.

SERVICE MENU

PICTURE SOUND THEATER OTHERS PIP LOW LIGHT HIGH LIGHT RF AFC1 RF AFC2 VCO(CW) I2C BUS CTRL

SELECT BY OPERATE BY

Fig.1

SYSTEM CONSTANT

MODEL :99– PURITY : NO CCD : YES V-CHIP : YES CAN V-CHIP : YES

EXIT BY

99999

999999999 999

SELECT BY OPERATE BY

Fig.2

EXIT BY

(7) SERVICE MENU setting

Verify what to set in the SERVICE MENU, and set whatever is necessary.(Fig.1) Refer to the SERVICE ADJUSTMENT for setting.

10 No. 51797

+ 21 hidden pages

JVC AV-27D50 Schematic

Specifications and Main Features

Frequently Asked Questions

User Manual

CONTENTS

SPECIFICATIONS

SAFETY PRECAUTIONS

FEATURES

MAIN DIFFERENCE LIST

HOW TO IDENTIFY MODELS

FUNCTIONS

SPECIFIC SERVICE INSTRUCTIONS