JVC AV-20420 Service Manual
52111200303
POWER
DISPLAY
INPUT
100+
RETURN+
MUTING
MENU
CHIP
EXIT
CHANNEL
VCR CONTROL
POWER
TV/VCR
REC
STOP
PAUSE
PLAYFFFF
REW
SLEEP
TIMER
VIDEO
STATUS
RM-C205
AV-20420
AV-20421
SERVICE MANUAL
COLOR TELEVISION
BASIC CHASSIS
AV-20420/SA,
FV5
AV-20421/SA
SLEEP
VIDEO
POWER
TIMER
STATUS
DISPLAY
INPUT
1
3
2
4
6
5
7
9
8
100+
RETURN+
0
MUTING
V—CHIP
+
CH
VOL
VOL
+
CH
MENU
EXIT
VCR CONTROL
CHANNEL
POWER
TV/VCR
PLAY
REW
PAUSE
REC
STOP
RM-C205
TABLE OF CONTENTS
1 PRECAUTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
2 SPECIFIC SERVICE INSTRUCTIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
3 ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-12
4 TROUBLE SHOOTING. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-30
COPYRIGHT © 2003 VICTOR COMPANY OF JAPAN, LTD.
No.52111
2003/03
AV-20420
AV-20421
SPECIFICATION
Items Contents
Dimensions (W x H x D) 50.3cm x 45.2cm x 49.3cm (19-7/8” x 17-7/8” x 19-1/2”)
Mass 19.9 kg (43.8 Ibs)
TV RF System CCIR(M)
Color Sound System NTSC, BTSC system (Multi Channel Sound)
TV Receiving Channels and Frequency
VHF LOW
VHF HIGH
TV/CATV Total Channel 180 channels
Intermediate Frequency
Video IF Carrier
Sound IF Carrier
Color Sub Carrier 3.58MHz
Power Input AC 120V, 60Hz
Power Consumption 87W
Picture Tube 20” (51cm) measured diagonally H : 40.6cm x V : 30.5cm
High Voltage 26.5kV±1kV (at zero beam current)
Speaker 5 x 9cm (2” x 3-1/2”) Oval type x 2
Audio Power Output 1W+1W
Antenna Terminal (VHF/UHF) F-type connector, 75ohm
Video / Audio Input (1 / 2 / 3)
Video (1 / 3)
Audio (1 / 2 / 3)
S-Video (1)
Component (2)
Audio Output (Variable) More then 0~1550mV(rms) (+6dBs)
Headphone Jack 3.5mm mini jack x 1
Remote Control Unit RM-C205 (AA/R6/UM-3 battery x 2) [AV-20420]
02ch~06ch : 54MHz~88MHz
07ch~13ch : 174MHz~216MHz
UHF
14ch~69ch : 470MHz~806MHz
CATV
54MHz~804MHz
Low Band : 02~06, A-8 by 02~06&01
High Band : 07~13 by 07~13
Mid Band : A~1 by 14~22
Super Band : J~W by 23~36
Hyper Band : W+1~W+28 by 37~64
Ultra Band : W+29~W+84 by 65~125
Sub Mid Band : 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 2)
RM-C205W (AA/R6/UM-3 battery x 2) [AV-20421]
Design & specifications are subject to change without notice.
1-2 (No.52111)
SECTION 1
PRECAUTIONS
AV-20420
AV-20421
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. Replacem ent 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 pr oducts 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 schematic s 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 pa rts list of Service manual ma y cause
shock, fire, or other hazards.
(4) Use isolation transformer when hot chassis.
The chassis and any sub-chassis contained in some products ar e
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 I SOLATED (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 m ust 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 con ditions 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 manufact urer of the
complete product.
(7) If any repair has been made to the ch assis, it is recomme nded 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 hig h
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 pro duct is saf e to operat e with out
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
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 A C ou tle t ( 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 exce ed 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
METAL PART
(11) High voltage hold down circuit ch eck.
After repair of the high voltage hold down circui t, this circuit shall b e
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.
POWER CORD
REPLACEMENT WARNING.
Connecting the white line side of power
cord to "WHT" character side.
PWB
White line side
A V
WHT
PW
“Leakage
(No.52111)1-3
AV-20420
AV-20421
SECTION 2
SPECIFIC SERVICE INSTRUCTIONS
2.1 FEATURES
• New chassis design enables use of a single board with simplified circuitry.
• Provided with miniature tuner (TV/CATV).
• Multifunctional remote control permits picture adjustment.
• Adoption of the CHANNEL GUARD function prevents the specific channels from being selected, unless the “ID number” is key in.
• I2C bus control utilizes single chip IC.
• Adoption of the VIDEO STATUS function.
• Adoption of the ON/OFF TIMER function.
• With 75ohm V/U in common (F-Type) ANT Terminal.
• SLEEP TIMER for setting in real time.
• Closed-caption broadcasts can be viewed.
• Audio Video input terminal.
• Variable Audio output terminal.
• Built-in MTS system.
2.2 SYSTEM BLOCK DIAGRAM
TUNER
TUNER
CONTROL
MEMORY IC
SCL
CPU
(MAIN MICON)
SCL
MTS/TONE
SDA
SDA
AFC
DECODER
IF
1 Chip
REMOTE
CONTROL
1-4 (No.52111)
2.3 MAIN DIFFERENCE LIST Parts Name AV-20420 AV-20421
BODY COLOR BLACK WHITE
FRONT CABINET LC10109-016A-A LC10109-017A-A
POWER KNOB LC30376-001A-A LC30376-002A-A
PUSH KNOB LC30271-001A-A LC30271-002A-A
REAR COVER LC10108-006A-A LC10108-007A-A
POWER CORD CLAMP LC20106-001D-A LC20106-002C-A
REMOTE CONTROL UNIT RM-C205-1C RM-C205W-1C
WHITE MARK (PACKING CASE) not used GQ40012-001A-A
AV-20420
AV-20421
(No.52111)1-5
AV-20420
AV-20421
2.4 DISASSEMBLY PROCEDURE
2.4.1 REMOVING THE REAR COVER
(1) Unplug the power plug.
(2) Remove the 5 screws [A], and 2 screws [B] as shown in
Fig.1.
(3) Withdraw the REAR COVER toward you..
CAUTION:
When reinstalling the rear cover, carefully push it i nward after
inserting the MAIN PWB into the rear cover groove.
2.4.2 REMOVING THE MAIN PWB
• Remove the REAR COVER.
(1) Raise the backside of the MAIN PWB slig htly . And remove
the PWB STOPPER [C] from the cabinet bottom.
(2) Withdraw the MAIN PWB backward.
(If necessary, remove the wire clamp and connectors, etc.)
2.4.3 REMOVING THE SPEAKER
• Remove the MAIN PW board.
(1) Remove the 2 screws [D].
(2) Then you can remove the SPEAKER.
2.4.4 CHECKING THE MAIN PW BOARD
(1) Pull out the MAIN CHASSIS (refer to REMOVING THE
MAIN PWB).
(2) Erect the chassis vertically so that you can easily check the
MAIN PWB from the reverse (solder) side.
CAUTION:
• When erecting the MAIN PWB, be careful so that there will
be no contacting with other PWB.
• Before turning power on, make sure that the CRT earth wire
and other connectors are 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.
2.4.5 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.
1-6 (No.52111)
FRONT CABINET
AV-20420
AV-20421
CRT SOCKET PWB
(Within MAIN PWB)
SPEAKER
D
REAR COVER
D
MAIN PWB
PWB STOPPER
BRAIDED ASSY
HVT
TUNER
DEG. COIL
C
Fig.1
B
A
(No.52111)1-7
AV-20420
AV-20421
2.5 REPLACEMENT OF MEMORY IC
2.5.1 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.
2.5.2 PROCEDURE FOR REPLACING MEMORY IC
(1) Power off
Switch the power off and unplug the power plug.
(2) Replace IC
Be sure to use a memory IC written with the initial setting data.
(3) Power on
Connect the power plug 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 TABLE “USER SETTING VALUE”, and if these are different, set the correct value.
(6) CHECK THE SYSTEM CONSTANT ITEMS
If the value of each item of a system setup is not correctly set
as a value peculiar to this television, operation of a
microcomputer and the output of an image do not become
suitable. Please set up the value of each item correctly,
according to the following description.
(1) Press the [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 (Fig.1).
(2) The SERVICE MENU screen of Fig.1 will be displayed.
(3) While the SERVICE MENU is displayed, again
simultaneously press the [DISPLAY] and [VIDEO
STATUS] keys to display the SYSTEM CONSTANT
screen (Fig.2).
(4) Refer to the Table 1 of SYSTEM CONSTANT SETTING,
and check the setting items. Where these differ, select
the item with the [CH (-/+)] key and adjust it with the [VOL
(-/+)] keys (The letters of the selected item are displayed
in yellow).
(5) The setting value will be stored automatically when
release the remote control unit keys.
(6) Press the [EXIT] key twice to return to the normal screen.
SERVICE MENU
PICTURE SOUND
GAME
LOW LIGHT HIGH LIGHT
RF AFC CHK
VCO(CW)
SELECT BY EXIT BY
OPERATE BY
EXIT
Fig.1
SYSTEM CONSTANT
MODEL
V-CHIP
CAN V-CHIP
******** *****
SELECT BY EXIT BY
OPERATE BY
:
:
:
*******
YES
YES
EXIT
Fig.2
(7) SERVICE MENU setting
Verify what to set in the SERVICE MENU, and set whatever is necessary. Refer to the SECTION 3 ADJUSTMENT for setting.
1-8 (No.52111)
2.5.3 SYSTEM CONSTANT SETTING
AV-20420
AV-20421
Setting Item
MODEL
V-CHIP
CAN V-CHIP
ޓAV-27220
ޓC-13210
Setting Content
AV-20220
C-20210
YES NO
YES NO
2.5.4 USER SETTING VALUE
Setting item Setting value
1. Use remote controller keys
POWER Off
CHANNEL CH 02
CHANNEL PRESET See OPERATING INSTRUCTIONS.
VOLUME 10
INPUT (TV/VIDEO) TV
DISPLAY Off
SLEEP TIMER 0
VIDEO STATUS STANDARD
2. Setting of MENU
TINT Center
COLOR Center
PICTURE Center
BRIGHT Center
DETAIL Center
BASS Center
TREBLE Center
BALANCE Center
MTS STEREO
TV SPEAKER ON
NOISE MUTING ON
SET VIDEO STATUS All center
SET CLOCK Unnecessary to set
ON/OFF TIMER OFF
LANGUAGE ENG
CLOSED CAPTION OFF
BACKGROUND BLACK
AUTO TUNER SETUP TUNER MODE : AIR
CHANNEL SUMMARY Unnecessary to set
V-CHIP OFF
SET LOCK CODE Unnecessary to set
AV-20420
AV-20220
YES
YES
/SA
AV-20421
AV-20220
YES
YES
/SA
(No.52111)1-9
AV-20420
AV-20421
2.5.5 SERVICE MENU SETTING ITEM
Menu item Setting item Menu item Setting item
PICTURE 1. BRIGHT GAME TINT
2. PICTURE COLOR
3. TV DETAIL PICTURE
4. TV BPF BRIGHT
5. TINT DETAIL
6. COLOR LOW LIGHT RED
7. EXT BRIGHT GREEN
8. EXT PICTURE BLUE
9. EXT DETAIL HIGH LIGHT GREEN
10. EXT BPF BLUE
11. EXT TINT RF AFC CHECK
12. EXT COLOR FINE
13. V SIZE STATUS
14. V CENTER VCO(CW) Refer to “ADJUSTMENTS PROCEDURE”
15. H POSITION
16. OSD H POSITION
17. OSD V POSITION
18. H AFC
19. RF AGC
20. OSD SELECT
SOUND 1. IN LEVEL
2. FH MON
3. ST VCO
4. PILOT
5. FILTER
6. LOW SEP
7. HIGH SEP
8. 5FH MON
9. SAP VCO
10. FIL OFF
[Do not adjust]
RF AFC
1-10 (No.52111)
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