JVC AV-28GT10UF, AV-28GT1BJF, AV-28GT1BUF/A /B /C, AV-28GT1SJF, AV-28GT1SUF/A /B /C Service Manual

52136200310

SERVICE MANUAL

COLOUR TELEVISION

AV-28GT1BJF, AV-28GT1BUF AV-28GT1SJF, AV-28GT1SUF AV-28GT10UF

/A, /B, /C,

TABLE OF CONTENTS

1 PRECAUTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3

2 SPECIFIC SERVICE INSTRUCTIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4

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

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

5 TROUBLESHOOTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-24

No.52136

2003/10

SPECIFICATION

Items Contents

Dimensions ( W × H × D ) 81cm × 51cm × 48.5cm Mass 36kg 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 NICAM / A2 (Germany system) Teletext System FLOF (Fastext) / TOP (German system) Tuning System Frequency synthesizer tuning system Number of CH memory position 100 ch Receiving

Frequency

Intermediate Frequency

Colour Sub Carrier Frequency PAL (4.43MHz), SECAM (4.43MHz), NTSC (3.58MHz/4.43MHz) Power Input AC220V ~ AC240V, 50Hz Power Consumption 148W(Max), 3W(Standby) Aerial Input Terminal 75Ω unbalanced, coaxial Picture Tube Visible size : 66cm (Measured diagonally) High Voltage 29kV Speaker Main:5.7cm × 16cm oval type × 2 / Tweeter: 8W,15W × 2 Audio Output 10W + 10W Input Video 1V(p-p) 75Ω

Output Video 1V(p-p) 75Ω

Input Terminal Rear Side EXT-1 (Video / Audio / RGB)

Output Terminal Rear Side EXT-1 (Video / Audio)

Remote Control Unit VE-30021286 (RM-C1512B), (AA/R06 dry battery × 2)

VHF Low 46.25MHz ~ 168.25MHz

VHF High 175.25MHz ~ 463.25MHz

UHF 471.25MHz ~ 863.25MHz

CATV S01-S41 & S75-S79

VIF 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')

S-Video Y : 1V(p-p) positive

C : 0.286V(p-p)

Audio (L/R) 500mV(rms) (-4dBs), High impedance (RCA pin jack × 2)

Audio (L/R) 500mV(rms), Low Impedance

EXT-2 (Video / Audio / RGB / S-VHS) EXT-3 (Video / Audio)

Right Side EXT-4 (Video / Audio)

EXT-2 (Video / Audio) EXT-3 (Video / Audio)

Right Side Headphone Jack (Stereo mini jack O3.5mm × 1)

: AV-28GT1BJF, AV-28GT1BUF VE-30021287 (RM-C1512S), (AA/R06 dry battery × 2)

: AV-28GH1SJF, AV-28GH1SJF, AV-28GH10UF

Design & specifications are subject to change without notice.

1-2 (No.52136)

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 B1 POWER SUPPLY check).

(6) The high voltage appli ed to the picture tube must confo rm

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 d rawing 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 gr ound frame and connecting the other end of the lead through a 10kΩ 2W resistor to the anode button.

(8) When service is required, obse rve 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 Chec k

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 ac ross 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 METAL PART

(No.52136)1-3

SECTION 2

SPECIFIC SERVICE INSTRUCTIONS

2.1 21-pin Euro connector (SCART) : EXT-1 / EXT-2 / EXT-3 Pin No. Signal Designation Matching Value EXT-1 EXT-2 EXT-3

1 AUDIO R output 500mV(rms) (Nominal),

Low impedance

2 AUDIO R input 500mV(rms) (Nominal),

High impedance

3 AUDIO L output 500mV(rms) (Nominal),

Low impedance 4 AUDIO GND --- Used Used Used 5 GND (B) --- Used Used Used 6 AUDIO L input 500mV(rms) (Nominal),

High impedance 7 B input 700mV(B-W), 75 Ω Used Used Not used 8 FUNCTION SW

(SLOW SW)

9 GND (G) --- Used Used Used

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

11 G input 700mV(B-W), 75 Ω Used Used Not used 12 SDA3 --- Not used Not used Not used 13 GND (R) --- Used Used Used 14 GND (YS) --- Used Used Used 15 R / C input R : 700mV(B-W), 75 Ω

16 Ys input

(FAST SW) 17 GND (VIDEO output) --- Used Used Used 18 GND (VIDEO input) --- Used Used Used 19 VIDEO output 1V

20 VIDEO / Y input 1V

21 COMMON GND --- Used Used Used

Low : 0V-3V, High : 8V-12V, High impedance

C : 300mV Low : 0V-0.4V, 75 Ω

High : 1V-3V, 75 Ω

(Negative sync),

(P-P)

75 Ω

(Negative sync),

(P-P)

75 Ω

(P-P)

, 75 Ω

Used Used Used

Used (R1) Used (R2) Used (R3)

Used Used Used

Used (L1) Used (L 2) Used (L3)

Used Used Used

Not used

(SCL / TV-LINK)

Used (R) Used (C2/R) Not used

Used Used Not used

Used Used Used

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

[Pin assignment]

21 19 17 15 13 11 9 7 5 3 1

1-4 (No.52136)

20 18 16 14 12 10 8 6 4 2

2.2 FEATURES

• It is a remote controlled color television.

• 100 programs from VHF, UHF bands or cable channels can be preset.

• It can tune cable channels.

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

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

• Side AV Input (EXT-4) available.

• Stereo sound systems (German + Nicam) are available.

• Full function Teletext (Fastext, Toptext).

• It is possible to connect headphone.

• Direct channel access.

• APS (Automatic Programming System).

• All programs can be named.

2.3 MAIN DIFFERENCE LIST

• Forward or backward automatic tuning.

• Sleep timer.

• Child Lock.

• Blue Background

• Panoramic mode.

• Comb FIlter

• CTI (Colour Transient Improvement)

•T-V Link

• 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)

• NTSC Playback.

AV-28GT1BJF

Part Name

MODEL COLOUR BLACK MODEL SILVER MODEL FRONT CABINET VE-20121496 VE-20120047 BACK COVER VE-20121498 VE-20111866 BACK DOOR VE-20108124 VE-20120043 FUNCTION BUTTON VE-20091798 VE-20096498 POWER BUTTON VE-20111864 VE-20120046 JVC LOGO VE-40013592 VE-40013593 REMOTE CONTROL UNIT VE-30021286 (RM-C1512B) VE-30021287 (RM-C1512S)

2.4 DIFFERENCE LIST BY ELECTRONICS

Part Name

MAIN PWB VE-20120603 VE-20120602 VE-20127797 VE-20127793 IC500 (MI-COM) VE-20139901 VE-20139901 VE-20137151 VE-20139902 IC502 (MEMORY) VE-20120620 VE-20120611 VE-20134093 VE-20126316

AV-28GT1BUF

AV-28GT1BJF AV-28KT1SJF

AV-28GT1BUF/A AV-28GT1SUF/A

AV-28GT1SJF

AV-28GT1SUF

AV-28GT10UF

AV-28GT1BUF/B AV-28GT1SUF/B

AV-28GT10UF

AV-28GT1BUF/C AV-28GT1SUF/C

2.5 DIFFERENCE LIST BY OSD LANGUAGE

Part Name

OSD LANGUAGES ENG, GER, FRE, ITA

AV-28GT1BUF/A AV-28GT1SUF/A

SPA, DUT, POR, TUR

AV-28GT1BUF/B AV-28GT1SUF/B

ENG, GER, FRE, SWE

NOR, DAN, FIN, GRE

AV-28GT1BUF/C AV-28GT1SUF/C

ENG, GER, CZE, POL

HUN, BUL, ROM, CRO

(No.52136)1-5

SECTION 3

DISASSEMBLY

3.1 DISASSEMBLY PROCEDULE

3.1.1 REMOVING THE REAR COVER

(1) Unplug the power cord. (2) Remove the 8 screws [A] as shown in the Fig. 1. (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 SPEAKER and TWEETER

• Remove the REAR COVER. (1) Remove the 4 screws [H], and remove the SPEAKER. (2) Remove the other hand SPEAKER in the same steps. (3) Remove the 2 screws [I], and remove the TWEETER. (4) Remove the other hand TWEETER in the same steps.

3.1.4 REMOVING THE MAIN PWB

• Remove the REAR COVER.

• Remove the BACK DOOR. (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.

3.1.8 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 PW Board.

3.1.9 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 PW board.

3.1.10 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 SIDE CONTROL PWB

• Remove the REAR COVER. (1) Remove the 4 screws [E]. (2) Remove the SIDE PWB.

3.1.6 REMOVING THE POWER SWITCH PWB

• Remove the REAR COVER. (1) Remove the 2 screws [F], and remove the POWER

SWITCH PWB.

3.1.7 REMOVING THE LED PWB

• Remove the REAR COVER.

• Remove the POWER SWITCH PWB. (1) Remove the 2 screws [G], and remove the LED PWB.

1-6 (No.52136)

CRT PWB

REAR COVER

BACK DOOR

MAIN PWB

TWEETER

SPEAKER

POWER SWITCH PWB

LED PWB

Fig.1

SIDE CONTROL PWB

(No.52136)1-7

3.2 REPLACEMENT OF CHIP COMPONENT

3.2.1 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.

3.2.2 SOLDERING IRON

(1) Use a high insulation soldering iron with a thin pointed end of it. (2) A 30w soldering iron is recommended for ea sily removing parts.

3.2.3 REPLACEMENT STEPS

1. How to remove Chip parts

2. How to install Chip parts

[Resistors, capacitors, etc.]

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

alternately melt the solder at each end.

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

[Transistors, diodes, variable resistors, etc.]

(1) Apply extra solder to each lead.

SOLDER

[Resistors, capacitors, 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. 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.

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

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

NOTE :

After removing the part, remove remaining solder from the pattern.

1-8 (No.52136)

(4) Then solder leads B and C.

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