JVC AV-21PX - Service Manual Immediate Download

No. 56039

AV-21PX

CONTENTS

s SPECIFICATIONS ........................................................................................................................... 2

s SAFETY PRECAUTIONS ................................................................................................................ 3

s FEATURES ...................................................................................................................................... 4

5 OPERATING INSTRUCTIONS (APPENDED) .............................................................................. 1-1

s SPECIFIC SERVICE INSTRUCTIONS ............................................................................................ 4

s SERVICE ADJUSTMENTS ............................................................................................................10

5 STANDARD CIRCUIT DIAGRAM (APPENDED) ......................................................................... 2-1

s PARTS LIST ................................................................................................................................... 29

BASIC CHASSIS

CM-F

No. 56039

Jul. 2000

AV-21PX

SERVICE MANUAL

COLOUR TELEVISION

AV-21PX

No. 56039

SPECIFICATIONS

Item

Content

Dimensions (W

× H × D)

596mm

× 468.5mm × 481.5mm

Mass

25kg

TV RF System

B / G, I, D / K, K1, M

Colour System

TV Mode

PAL / SECAM / NTSC3.58 / NTSC4.43

VIDEO Mode

PAL / SECAM / NTSC3.58 / NTSC4.43

Receiving Frequency

VHF (VL)

46.25MHz ~ 168.25MHz

VHF (VH)

175.25MHz ~ 463.25MHz

UHF

471.25MHz ~ 863.25MHz

CATV

q Cable TVs of Mid (X-Z, S1-S10)

Super (S11-S20) & Hyper (S21-S41) bands receivable

Intermediate

VIF Carrier

38.0MHz

Frequency

31.5MHz (6.5MHz)

SIF Carrier

32.0MHz (6.0MHz)

32.5MHz (5.5MHz)

33.5MHz (4.5MHz)

Colour Sub Carrier Frequency

PAL (4.43MHz), SECAM (4.40625MHz / 4.25MHz)

NTSC (3.58MHz / 4.43MHz)

Aerial Input Terminal

Unbalanced

Power Input

AC110 ~ 240V, 50/60Hz

Power Consumption

135W (Max.) / 89W (Avg.)

Picture Tube

Visible size : 51cm measured diagonally

High Voltage

29kV

+1/-1.5kV (at zero beam current)

Speaker

× 12cm Oval type × 2

Audio Output

5W + 5W

Input (S/Video-1,

Video

1Vp-p, 75

Video-2 & -3, Audio)

S/Video

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

)

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

)

Audio (L/R)

500mVrms (

-4dBs), High impedance

Output

Video

1Vp-p, 75

Audio (L/R)

500mVrms (4dBs), Low impedance

Headphone Jack

Stereo mini jack (3.5ø)

Remote Control Unit

RM-C235-1C

(Battery size : AA/R06/UM-3

× 2)

Design & specifications are subject to change without notice.

No. 56039

AV-21PX

SAFETY PRECAUTIONS

When service is required, observe the original lead dress. Ex-

tra 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 com-

ponents.

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 ter-

minals, 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 elec-

trical 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 hav-

ing 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.

(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 ex-

posed 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.).

q 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 volt-

meter having 1000 ohms per volt or more sensitivity in the fol-

lowing manner. Connect a 1500

10W resistor paralleled by a

0.15

µF 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 volt-

age measured must not exceed 0.75V AC (r.m.s.). This corre-

sponds 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.).

The design of this product contains special hardware, many

circuits and components specially for safety purposes. For con-

tinued protection, no changes should be made to the original

design unless authorized in writing by the manufacturer. Re-

placement parts must be identical to those used in the original

circuits. Service should be performed by qualified personnel

only.

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 manufac-

turer of responsibility for personal injury or property damage

resulting therefrom.

Many electrical and mechanical parts in the products have spe-

cial safety-related characteristics. These characteristics are of-

ten not evident from visual inspection nor can the protection

afforded by them necessarily be obtained by using replace-

ment components rated for higher voltage, wattage, etc. Re-

placement parts which have these special safety characteris-

tics are identified in the parts list of Service manual. Electrical

components having such features are identified by shad-

ing on the schematics and by (!) on the parts list in Ser-

vice 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.

Don't short between the LIVE side ground and ISOLATED

(NEUTRAL) side ground or EARTH side ground when re-

pairing.

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 ISO-

LATED (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 bro-

ken.

If any repair has been made to the chassis, it is recommended

that the B1 setting should be checked or adjusted (See AD-

JUSTMENT OF B1 POWER SUPPLY).

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 com-

ponent damage, therefore operation under excessive high volt-

age conditions should be kept to a minimum, or should be pre-

vented. If severe arcing occurs, remove the AC power immedi-

ately and determine the cause by visual inspection (incorrect

installation, cracked or melted high voltage harness, poor sol-

dering, etc.). To maintain the proper minimum level of soft X-

Ray emission, components in the high voltage circuitry includ-

ing the picture tube must be the exact replacements or alterna-

tives approved by the manufacturer of the complete product.

Do not check high voltage by drawing an arc. Use a high volt-

age meter or a high voltage probe with a VTVM. Discharge the

picture tube before attempting meter connection, by connect-

ing a clip lead to the ground frame and connecting the other

end of the lead through a 10k

2W resistor to the anode but-

ton.

AC VOLTMETER

(HAVING 1000

/V,

OR MORE SENSITIVITY)

PLACE THIS PROBE

ON EACH EXPOSED

METAL PART

1500

10W

0.15

µF AC-TYPE

GOOD EARTH GROUND

AV-21PX

No. 56039

SPECIFIC SERVICE INSTRUCTIONS

DISASSEMBLY PROCEDURE

REMOVING THE REAR COVER

Unplug the AC power cord.

Remove the 12 screws marked "A". (See Fig. 3 on the next

page.)

Withdraw the rear cover backward.

REMOVING THE PB BASE

After removing the rear cover.

Slightly raise both sides of the PB Base by hand and remove

the 2 claws under both sides of the PB Base from the front

cabinet. (See Fig. 3.)

Withdraw the PB Base backward.

(If necessary, take off the wire clamp, connectors etc.)

REMOVING THE AV TERMINAL BOARD

After removing the rear cover.

Remove the 2 screws marked "B". (See Fig. 3.)

Unhook the claw (marked "C") of the AV Terminal Board from

the PW Board by lifting it upward. (See Fig. 1.)

Then remove the AV Terminal Board backward (in the arrow

direction marked "D"). (See Fig. 1.)

REMOVING THE CONTROL BASE

After removing the Rear Cover and the PB Base.

While pushing down the claws marked "E", remove the Control

Base forward (in the arrow direction marked "F"). (See Fig. 2.)

(If necessary, take off the wire clamp, connectors, etc.)

FEATURES

q New chassis design enables use of an interactive on-screen

control.

q Pure flat CRT produces fine textured picture in every detail.

q Wide range voltage for AC power input.

q With AUDIO / VIDEO / S-VIDEO INPUT & OUTPUT terminals.

q MUTING button can reduce the audio level to zero instantly.

q Functional remote control to operate TV set (for channel select,

volume control, power ON/OFF, etc.) from a distance.

q I2C bus control utilizes single chip ICs for IF, V/C (Video/Chroma)

and VSM (Video Status Memory).

q By means of AUTO PROGRAM, the TV stations can be selected

automatically and the TV channels can also be rearranged au-

tomatically.

q Built-in ECO MODE (ECONOMY, ECOLOGY)

In accordance with the brightness in a room, the brightness and/

or contrast of the picture can be adjusted automatically to make

the optimum picture which is easy on the eye.

q Built-in ON TIMER & RETURN +.

q By means of ALC (Auto Level Control), the audio output is auto-

matically controlled at a constant level.

REMOVING THE SPEAKER

After removing the rear cover.

Remove the Speaker block by removing the 2 screws marked

"G" . (See Fig. 3.)

Remove the Speaker by removing the 4 screws marked "H".

(See Fig. 3.)

Follow the same steps for removing the other hand speaker.

CHECKING THE MAIN PW BOARD

To check the back side of the Main PW Board, follow the next steps.

Pull out the PB Base. (Refer to "REMOVING THE PB BASE".)

Erect the PB Base vertically so that you can easily check the

back side of the Main PW Board.

CAUTION:

When erecting the PB Base, be careful so that there will be no

contacting with other PW Board.

Before turning on power, make sure that the CRT earth wire

and other connectors are properly connected.

When repairing, connect the Deg. coil to the DEG. connector

on the Main PW Board.

WIRE CLAMPING AND CABLE TYING

Be sure to clamp the wire.

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.

Fig. 1

Fig. 2

AV TERMINAL

BOARD

[REAR SIDE]

CONTROL BASE

[FRONT SIDE]

PB BASE

No. 56039

AV-21PX

Fig. 3

CRT SOCKET

PWB

FRONT CABINET

FRONT CONTROL PWB

INNER PIN PWB

CONTROL BASE

REAR COVER

CLAW

AV TERMINAL

BOARD

SPEAKER

MAIN PWB

PB BASE

B (×2)

Fig. 2

SPEAKER

Fig. 1

(

×2)

(

×2)

H (×4)

(

×4)

A (×12)

AV SW PWB

IF PWB

ALC PWB