JVC AV-20D304/SA Service Manual
52103200302
AV-20D304
SERVICE MANUAL
COLOR TELEVISION
BASIC CHASSIS
AV-20D304/SA
FE2
TABLE OF CONTENTS
1 PRECAUTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
2 SPECIFIC SERVICE INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
3 ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-10
COPYRIGHT © 2003 VICTOR COMPANY OF JAPAN, LTD.
No.52103
2003/02
AV-20D304
SPECIFICATION
Items Contents
Dimensions (W x H x D) 59.2cm x 45.6cm x 48.7cm (23-3/8” x 18” x 19-1/4”)
Mass 20.4kg (45 Ibs)
TV RF System CCIR(M)
Color Sound System NTSC, BTSC system (Multi Channel Sound)
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 180 channels
Intermediate Frequency
Video IF Carrier
Sound IF Carrier
Color Sub Carrier 3.58MHz
Power Input 120V AC, 60Hz
Power Consumption 75W
Picture Tube 20” (51cm) measured diagonally H : 40.6cm x V : 30.5cm
High Voltage 26.3kV±0.5kV (at zero beam current)
Speaker 5 x 9cm (2” x 3-1/2”) Oval type x 2
Audio Power Output 1.2W x 2
Antenna terminal (VHF/UHF) F-type connector, 75ohm
Video / Audio Input (1 / 2 / 3)
Video (1 / 3)
Audio (1 / 2 / 3)
S-Video (Input 1)
Component (Input 2)
Audio Output (Variable) More then 0~1550mV(rms) (+6dBs)
Headphone Jack 3.5mm mini jack x 1
Remote Control Unit RM-C1254G (AA battery x 2)
02ch~06ch : 54MHz~88MHz
07ch~13ch : 174MHz~216MHz
14ch~69ch : 470MHz~806MHz
54MHz~804MHz
02~06, A-8 by 02~06&01
07~13 by 07~13
A~1 by 14~22
J~W by 23~36
W+1~W+28 by 37~64
W+29~W+84 by 65~125
A8, A4~A1 by 01, 96~99
45.75MHz
41.25MHz (4.5MHz)
1V(p-p), 75ohm (RCA pin jack x 2)
500mV(rms) (-4dBs), high Impedance (RCA pin jack x 8)
Mini DIN 4pin x 1
Y : 1V(p-p) positive (negative sync provided, when terminated with 75ohm)
C : 0.286V(p-p) (burst signal when terminated with 75ohm)
RCA pin jack x 3
Y : 1V(p-p) positive (negative sync provided, when terminated with 75ohm)
Pb/Pr : 0.7V(p-p) 75ohm
low impedance (400Hz when modulated 100%) (RCA pin jack x )
Design & specifications are subject to change without notice.
1-2 (No.52103)
SECTION 1
PRECAUTIONS
AV-20D304
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 that 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
(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 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) 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) 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).
(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
10kΩ 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.
(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.
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 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 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 1000 ohms per volt or more sensitivity in
the following manner. Connect a 1500ohm 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
GOOD EARTH GROUND
1500 10W
ON EACH EXPOSED
ME TAL PART
(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".
This mark shows a fast
operating fuse, the
letters indicated below
show the rating.
A V
POWER CORD
REPLACEMENT WARNING.
Connecting the white line side of power
cord to "WHT" character side.
PWB
White line side
WHT
PW
(No.52103)1-3
AV-20D304
2.1 FUNCTIONS
SECTION 2
SPECIFIC SERVICE INSTRUCTIONS
[FRONT PANEL]
MENU POWERCHANNEL
[REAR PANEL] [REMOTE CONTROL UNIT]
VOLUME
(RM-C1254G)
1-4 (No.52103)
2.2 DISASSEMBLY PROCEDURE
AV-20D304
2.2.1 REMOVING THE REAR COVER
(1) Unplug the power plug.
(2) As shown in the Fig.1, remove the 9 screws [A].
(3) As shown in Fig.1, remove the 4 screws [B].
(4) Then remove the REAR COVER toward you.
2.2.2 REMOVING THE MAIN PWB
• Remove the REAR COVER.
(1) Raise the backside of the MAIN PWB, and remove the
PWB STOPPER [C] from the cabinet.
(2) Withdraw the MAIN PWB backward. (If necessary, remove
the wire clamp, connectors etc.)
2.2.3 REMOVING THE SPEAKER
• Remove the REAR COVER.
(1) As shown in Fig.1, remove the 4 screws [D], then remove
the speaker.
(2) Follow the same steps when remove the other hand
speaker.
NOTE:
When removing the 4 screws [D] of the speaker, remove the
lower side screw first, and then remove the upper one.
2.2.4 CHECKING THE PW BOARD
• Remove the REAR COVER.
(1) Pull out the MAIN CHASSIS (refer to REMOVING THE
MAIN PWB).
(2) Erect the MAIN CHASSIS vertically so that you can easily
check the backside of the PW Board.
CAUTION:
• When erecting the chassis, 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
onnected to the CRT SOCKET PW board.
2.2.5 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.
(No.52103)1-5
AV-20D304
FEONT CABINET
SPEAKER
D
CRT SOCKET PWB
MAIN PWB
HVT
SPEAKER
D
PWB STOPPER
C
REAR COVER
1-6 (No.52103)
B
A
POWER CORD
Fig.1
2.3 MEMORY IC REPLACEMENT
2.3.1 MEMORY IC
This TV use memory IC.
In the memory IC, there are memorized data for correctly operating the video and deflection circuits.
When replacing the memory IC, be sure to use IC written with the initial values of data.
2.3.2 PROCEDURE FOR REPLACING MEMORY IC
(1) Power off
Switch the power off and unplug the power cord from the outlet.
(2) Replace IC
Be sure to use a memory IC written with the initial setting data.
(3) Power on
Connect the power cord to the outlet and switch the power on.
(4) Setting of receive channels
Set the receive channels. For setting, refer to the OPERATING INSTRUCTIONS.
(5) User settings
Check the user setting items according to “USER SETTING VALUES”, and if these are different, set the correct value.
(6) SERVICE MENU setting
Verify what to set in the SERVICE MENU, and set whatever is necessary. Refer to the ADJUSTMENT for setting.
AV-20D304
SERVICE MENU
1.V/C(S)
3.SOUND(A)
7.LOW LIGHT
9.VCO
11.I2C BUS
SELECT BY
OPERATE BY
2.DEF(D)
4.OTHERS(F)
8.HIGH LI GHT
EXIT BY
EX IT
KEY ASSIGNMENT OF REMOTE CONTROL UNIT
DISPLAY
SLEEP
TIMER
VIDEO
STATUS
CHANNEL
VOLUME
- / +
+ / -
EXIT
(No.52103)1-7
AV-20D304
2.3.3 USER SETTING VALUES
Setting item Setting value Setting item Setting value
REMOTE CONTROL UNIT KEY
POWER OFF DISPLAY OFF
CHANNEL CH-02 VIDEO STATUS DYNAMIC
VOLUME 15 HYPER SURROUND OFF
TV/VIDEO TV
SETTING OF MENU
PICTURE MODE INITIAL SETUP MODE
TINT Center LANGUAGE ENG
COLOR Center FRONT PANELLOCK OFF
PICTURE +8 V2 COMPONENT-IN NO
BRIGHT Center AUTO SHUT OFF OFF
DETAIL +10 CLOSED CAPTION OFF
NOISE MUTING ON AUTO TUNER SET UP AIR
SOUND MODE CHANNEL SUMMARY Unnecessary to set
BASS Center V-CHIP OFF
TREBLE Center SET LOCK CODE (0000) Unnecessary to set
BALANCE Center XDS ID ON
MTS STEREO
CLOCK / TIMERS MODE
SET CLOCK MANUAL
TIME ZONE PACIFIC
D.S.T. OFF
ON / OFF TIMER OFF
1-8 (No.52103)
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