JVC AV-21VT15 User manual

SERVICE MANUAL
COPYRIGHT © 2005 Victor Company of Japan, Limited No.YA254
2005/4
FLAT COLOR TELEVISION
YA25420051
AV-21VT15/R
TABLE OF CONTENTS
1 PRECAUTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
2 SPECIFIC SERVICE INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
3 DISASSEMBLY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7
4 ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-13
5 TROUBLESHOOTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-29
BASIC CHASSIS
CW

1-2 (No.YA254)
SPECIFICATION
Design & specifications are subject to change without notice.
Items Contents
Dimensions (W ×H ×D) 64.9cm ×46.55cm ×47.35cm
Mass 25kg
TV RF System M / N
Color System TV Mode
Video Mode
NTSC / PAL-M / PAL-N
NTSC / PAL-M / PAL-N
Stereo System MTS (Multi-Channel Television Sound)
Receiving Frequency VHF Low
VHF High
UHF
CATV
46.25 MHz ~ 140.25 MHz (AS0 ~ S6)
147.25 MHz ~ 423.25 MHz (S7 ~ S36)
431.25 MHz ~ 863.25 MHz (S37 ~ C57)
Mid : X ~ Z, S1 ~ S10
Super: S11 ~ S20
Hyper: S21 ~ S41
Intermediate
Frequency
VIF 38.0MHz
SIF 33.5MHz (4.5MHz)
Color Sub Carrier Frequency 3.58MHz (NTSC)
Aerial Input Terminal 75Ωunbalanced, coaxial
Power Input AC110V-AC240V, 50Hz / 60Hz (Operating Voltage 90V ~ 260V)
Power Consumption 121W (Max.) / 81W (Avg.)
Picture Tube A51QDX993X006
21-inch, aspect ratio 4:3, flat square face type, tinted
Screen Size Visible size :51.0cm (Diagonal) / 41.6cm ×31.5cm (H ×V)
High Voltage 29kV ± 1.5kV (at zero beam current)
Speaker 6.5cm ×13cm, Oval type ×2
Audio Output 7W + 7W
Video / Audio Input
[1/2/3]
S-Video [1] Mini-DIN 4 pin ×1
Y: 1V(p-p), positive (negative sync provided), 75Ω
C: 0.286V(p-p) (Burst signal), 75Ω
Video [1/2/3] 1V(p-p), negative sync, 75Ω, RCA pin jack ×3
Audio [1/2/3] 500mV(rms) (-4dBs ), high impedance, RCA pin jack ×6
Component
Video [2]
RCA pin jack ×3
Y:1V(p-p), positive (negative sync), 75Ω
Cb/Cr:0.7V(p-p), 75Ω
Video / Audio Output Video
Audio
1V(p-p), 75Ω, RCA pin jack ×1
500mV(rms)(-4dBs), Low impedance (400Hz when modulated 100%), RCA pin jack ×2
Headphone 3.5mm stereo mini jack ×1
Remote Control Unit RM-C1288-1H
(AA/R06/UM-3 battery ×2)

(No.YA254)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 B1 POWER SUPPLY check).
(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 1000Ωper 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)
PLACE THIS PROBE
ON EACH EXPOSED
METAL PART
1500 10W
0.15 F AC-TYPE
GOOD EARTH GROUND

1-4 (No.YA254)
SECTION 2
SPECIFIC SERVICE INSTRUCTIONS
2.1 FEATURES
• New chassis design enables use of an interactive on-screen control.
• Pure flat CRT produces fine textured picture in every detail.
• Wide range voltage (110V ~ 240V) for AC power input.
• With AUDIO/VIDEO/S-VIDEO/COMPONENT input terminals.
•I
2C bus control utilizes single chip ICs.
• By means of AUTO PROGRAM, the TV stations can be selected automatically and the TV channels can also be rearranged
automatically.
• Built-in DIGITAL 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.
• Built-in OFF TIMER & RETURN +.
2.2 FUNCTIONS
REMOTE CONTROL UNIT
RM-C1288-1H
1
2
3
4
5
6
7
8
9
10
11
COLOR SYSTEM key
FAVORITE CHANNEL keys
DISPLAY BACK key
CLOSED CAPTION key
SOUND TURBO key
PICTURE MODE key
RETURN + key
OFF TIMER key
CHANNEL (-/+) keys
ECO key
12
13
14
15
16
17
18
19
20
POWER key
TV / VIDEO key
MENU (OK) key
MUTING key
Number keys
100+ key
VOLUME (-/+) keys
Not used
CINEMA SURROUND key
1
2
3
5
6
7
8
9
10
11
12
4
13
14
16
18
17
19
20
15
MENU ( / , / ) keys

(No.YA254)1-5
FRONT PANEL CONTROLS
REAR TERMINAL
1
2
3
4
5
6
7
8
9
10
11
IN (VIDEO-3) : VIDEO
HEADPHONE jack
IN (VIDEO-3) : AUDIO L/MONO
IN (VIDEO-3) : AUDIO R
MENU (OK) button
CHANNEL (-/+) buttons
VOLUME (-/+) buttons
Remote control sensor
ECO sensor
POWER lamp
MAIN POWER button
IN (VIDEO-3)
V R
L / MONO
POWER
OK
CHANNEL VOLUME
MENU
321 4 6 7 8 9 10 11
5
2
3
4
5
6
7
8
9
10
11
12
1313
VIDEO-1 INPUT TERMINAL
S-VIDEO
VIDEO
AUDIO L/MONO
AUDIO R
COMPONENT (VIDEO-2) INPUT TERMINAL
Y/VIDEO
C
B
C R
AUDIO L/MONO
AUDIO R
OUTPUT TERMINAL
VIDEO
AUDIO L
AUDIO R
Aerial input terminal
1
V
L
RR
L/MONO
Y
C
B
C R
/V
V
S
OVER
L
R
/MONO
OUTPUT
VIDEO-1 COMPONENT
(VIDEO-2)
INPUT
INPUT
7
4
3
212
1
9
5 6 10 118
13