JVC AV-28RT4BU/A, AV-28RT4BU/B, AV-28RT4BU/C, AV-28RT4SU/A, AV-28RT4SU/B Service Manual

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SERVICE MANUAL

COLOUR TELEVISION

YA07920052

AV-28RT4BU/A, AV-28RT4BU/B, AV-28RT4BU AV-28RT4SU

RM-C1100

STEREO

/C, AV-28RT4SU/A,

/B, AV-28RT4SU/C

TABLE OF CONTENTS

1 PRECAUTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4

2 SPECIFIC SERVICE INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5

3 DISASSEMBLY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6

4 ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-10

5 TROUBLESHOOTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-20

No.YA079

2005/2

SPECIFICATION

Item Content

Dimensions ( W × H × D ) 76.5cm × 58.5cm × 48.6cm

Mass 33.8kg

TV RF System B/G, D/K, L/L'

Colour System TV Mode PAL / SECAM

Video Mode PAL / SECAM / NTSC 3.58 / NTSC 4.43

Sound System A2 (B/G, D/K), NICAM (B/G, D/K, L/L')

Teletext System Fastext / TOP / WST

Tuning System Frequency synthesizer tuning system

Receiving Frequency VHF(VL)

VHF(VH)

Intermediate Frequency VIF

Colour Sub Carrier Frequency PAL

SECAM

Power Input AC220V - AC240V, 50Hz

Power Consumption 120W (Max) / 3W (Standby)

Aerial Input Terminal 75Ω unbalanced, coaxial Picture Tube Size Visible size : 66cm (28”), Measured diagonally (H: 58.3cm × V: 33.0cm)

High Voltage 29kV (at zero bean current)

Speaker 5.7cm × 12.6cm, Oval type × 2

Audio Output 10W + 10W (THD10%)

EXT-1 Input / Output 21-pin Euro connector (SCRAT socket) × 1 EXT-2 Input / Output 21-pin Euro connector (SCRAT socket) × 1

EXT-3 Input Video

Audio (L/R)

Headphone jack Stereo mini jack 3.5mm

Remote Control Unit VE-30017763 (RM-C1100), (AA/R06 dry battery × 2)

Design & specifications are subject to change without notice.

46.25MHz - 168.25MHz

175.25MHz - 463.25MHz

UHF

471.25MHz - 863.25MHz

CATV

S01 - S41 & S75 - S79

38.9MHz (B/G, D/K, L) / 33.9MHz (L')

SIF

33.4MHz (5.5MHz:B/G) / 32.9MHz (6.0MHz:D/K) /

32.4MHz (6.5MHz:L) / 40.4MHz (6.5MHz:L')

4.43MHz

4.40625MHz / 4.43MHz

NTSC

3.58MHz / 4.43MHz

1V(p-p) 75Ω, RCA pin jack × 1 500mV(rms) (-4dBs), High Impedance, RCA pin jack × 2

1-2 (No.YA079)

21-PIN EURO CONNECTOR (SCRAT) : EXT-1 / EXT-2

Pin No. Signal designation Matching value EXT-1 EXT-2

1 AUDIO R output 500mV(rms) (Nominal), Low impedance Used (TV OUT) Used (LINE OUT)

2 AUDIO R input 500mV(rms) (Nominal), High impedance Used (R1) Used (R2)

3 AUDIO L output 500mV(rms) (Nominal), Low impedance Used (TV OUT) Used (LINE OUT)

4 AUDIO GND --- Used Used

5 GND (B) --- Used Used

6 AUDIO L input 500mV(rms) (Nominal), High impedance Used (L1) Used (L2)

7 B input 700mV

8 FUNCTION SW (SLOW SW) Low : 0V-3V

, 75 Ω Used Not used

(B-W)

Used Used

High : 8V-12V, High impedance

9 GND (G) --- Used Used

10 SCL / T-V LINK --- Not used Used

(SCL / T-V LINK)

11 G input 700mV(B-W), 75 Ω Used Not used

12 SDA3 --- Not used Used

13 GND (R) --- Used Used

14 GND (YS) --- Used Not used

15 R / C input R : 700mV

C : 300mV

(B-W)

(P-P)

, 75 Ω

16 Ys input (FAST SW) Low : 0V-0.4V, 75 Ω

Used (R) Used (C)

Used Not used

High : 1V-3V, 75 Ω

17 GND (VIDEO output) --- Used Used

18 GND (VIDEO input) --- Used Used

19 VIDEO output 1V

20 VIDEO / Y input 1V

(Negative sync),75 Ω Used (TV OUT) Used (LINE OUT)

(P-P)

(Negative sync), 75 Ω Used Used

(P-P)

21 COMMON GND --- Used Used

(P-P= Peak to Peak, B-W= Blanking to white peak)

[Pin assignment]

20 18 16 14 12 10 8 6 4 2

21 19 17 15 13 11 9 7 5 3 1

(No.YA079)1-3

SECTION 1

PRECAUTION

1.1 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) Don't short between the LIVE side ground and

ISOLATED (NEUTRAL) 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 the LIVE side GND and ISOLATED (NEUTRAL) side GND or EARTH side GND at the same time with a measuring apparatus (oscilloscope etc.). If above note will not be kept, a fuse or any parts will be broken.

(5) 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).

(6) 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.

(7) 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 10kΩ

2W resistor to the anode button.

(8) 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.

(9) 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, screw heads, earphone jack, control shafts, etc.) to be sure the product is safe to operate without danger of electrical shock.

a) 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 3000V 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.

b) 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 1000Ω per volt or more sensitivity in the following manner. Connect a 1500Ω 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.).

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

0.15 F AC-TYPE

PLACE THIS PROBE

1500 10W

GOOD EARTH GROUND

ON EACH EXPOSED ME TAL PAR T

1-4 (No.YA079)

SECTION 2

SPECIFIC SERVICE INSTRUCTIONS

2.1 FEATURES

• It is a remote controlled colour television.

• Controlling the TV is very easy by its menu driven system.

• It has 2 Euroconnector sockets for external device (such as video recorder, video games, audio set, etc.)

• Stereo sound systems (A2 / Nicam) are available.

• Full function Teletext (Fastext, Toptext, WST).

• It is possible to connect headphone.

• Direct channel access.

• APS (Automatic Programming System).

2.2 MAIN DIFFERENCE LIST

Items AV-28RT4BU AV-28RT4SU

CABINET COLOUR BLACK SILVER

• All programs can be named.

• Forward or backward automatic tuning.

• Sleep timer. / . Child Lock. / . T-V Link

• Blue Background / . NTSC Playback.

• Automatic sound mute when no transmission.

• 5 minutes after the broadcasting (close down), the TV switches itself automatically to stand-by mode.

• WSS (Wide Screen Signaling)

Items

MAIN PWB VE-20160397 VE-20160371 VE-20160393

IC500 (MI-COM) VE-30029564 VE-30029565 VE-20173330

IC502 (MEMORY) VE-20120610 VE-20134092 VE-20126318

English, German, French, Italian,

OSD LANGUAGES

Spanish, Dutch, Portuguese, Turkish

AV-28RT4BU/A AV-28RT4SU/A

English, German, French, Swedish, norwegian, Danish, Finnish, greek

AV-28RT4BU/B AV-28RT4SU/B

AV-28RT4BU/C AV-28RT4SU/C

English, German, Czech, Polish, Hungarian, Bulgarian, Romanian, Croatian

(No.YA079)1-5

SECTION 3

DISASSEMBLY

3.1 DISASSEMBLY PROCEDURE

3.1.1 REMOVING THE REAR COVER

(1) Unplug the power cord. (2) Remove the 10 screws [A]. (3) Remove the 4 screws [B]. (4) Withdraw the REAR COVER toward you.

3.1.2 REMOVING THE BACK DOOR

• Remove the REAR COVER. (1) Remove the 2 screws [C]. (2) Withdraw the BACK DOOR toward you.

3.1.3 REMOVING THE MAIN PWB

• Remove the REAR COVER. (1) Remove the 4 screws [D]. (2) Slightly raise the both sides of the MAIN PWB by hand and

withdraw the MAIN PWB backward.

[CAUTION]

If necessary, take off the wire clamp, connectors etc. Be careful enough when developing a MAIN PWB.

3.1.4 REMOVING THE CHASSIS BASE

• Remove the REAR COVER. (1) Remove the 2 screws [E]. (2) Remove the CHASSIS BASE.

3.1.10 CHECKING THE PW BOARD

• To check the back side of the PW Board. (1) Pull out the PW Board. (Refer to REMOVING THE MAIN

PWB).

(2) Erect the PW Board vertically so that you can easily check

the back side of the PWB.

[CAUTION]

• When erecting the PW Board, be careful so that there will be

no contacting with other PW Board.

• Before turning on power, make sure that the wire connector

is properly connected.

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

confirm that the CRT EARTH WIRE (BRAIDED ASS'Y) is connected to the CRT SOCKET PWB.

3.1.11 WIRE CLAMPING AND CABLE TYING

(1) Be sure to 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.

3.1.5 REMOVING THE AV & HEADPHONE PWB

• Remove the REAR COVER.

• Remove the MAIN PWB. (1) Remove the 2 screws [F]. (2) Remove the AV & HEADPHONE PWB.

3.1.6 REMOVING THE FRONT CONTROL PWB

• Remove the REAR COVER.

• Remove the CHASSIS BASE. (1) Remove the 3 screws [G], and remove the FRONT

CONTROL PWB.

3.1.7 REMOVING THE POWER SWITCH PWB

• Remove the REAR COVER.

• Remove the CHASSIS BASE. (1) Remove the 2 screws [H], and remove the POWER

SWITCH PWB.

3.1.8 REMOVING THE LED PWB

• Remove the REAR COVER.

• Remove the CHASSIS BASE. (1) Remove the 2 screws [I], and remove the LED PWB.

3.1.9 REMOVING THE SPEAKER

• Remove the REAR COVER. (1) Remove the 4 screws [J], and remove the SPEAKER. (2) Remove the opposite side similarly.

1-6 (No.YA079)

(x10)

CRT SOCKET PWB

REAR COVER

(x4)

(x2)

BACK DOOR

CHASSIS FRAME

CHASSIS BASE

(x2)

(x4)

MAIN PWB

SPEAKER

(x3)

(x2)

POWER SWITCH PWB

PICTURE TUBE

(x4)

FRONT CONTROL PWB

(x2)

AV & HEADPHONE PWB

(x2)

LED PWB

FRONT CABINET

Fig.1

(No.YA079)1-7

+ 14 hidden pages