JVC AV-27920 User manual

JVC
CONTENTS
| | SPECIFICATIONS re 2
@ SAFETY PRECAUTIONS -*:<**2**-*22*% Ce ee 3
@ FEATURES °-«--++-e +22 e022 eee ene ey 4
i | DIFFERENCE LIST OF MAIN PARTS i ee 4
a OPERATING INSTRUCTIONS ee ee ee ee ay 5
i] SPECIFIC SERVICE INSTRUCTIONS ee ra Glatelo\bidsa ale ake Sierra 6
i | SERVICE ADJUSTMENTS ee 10
% STANDARD CIRCUIT DIAGRAM (APPENDED) «+ ---+++--crereeeee reer e reese ee ee eee es 2-1
i] PARTS LIST ee ry TUTE ECELELET TEE er 25 F
COPYRIGHT © 1998 VICTOR COMPANY OF JAPAN, LTD.
No. 51370
Mar. 1998

AV-27920
SPECIFICATIONS
Dimensions (W x H x D}
Mass
TV RF System
Color Sound System
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/ICATV Total Channel
Intermediate Frequency
Video IF Carrier
Sound JF Carrier
Color Sub Carrier
Power Input
Power Consumption
Picture Tube
High Voltage
Audio Power Output
Input
Video Input
Audio Input
Antenna Terminal
Remote Control Unit
25-3/4" x 23-3/8" x 19-1/2” / 65.4em x 59.3cm x 49.4cm
68.5 ibs / 31.1 kg
CCIR(M)
(Multi Channel Sound)
(02~06) 54MHz~88MHz
(07~13) 174MHz~216MHz
(14~69) 470MH2~806MHz
(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)
180 Channels
(64MHz~804MHz)
45.75MHz
41.25MHz (4.5MHz)
3.58MHz
120V AC, 60Hz
113W (US) /1.8A (CA)
27” (68cm) Measured Diagonally
29kV+1kV (at zero beam current)
2" x 3-1/2" /5 x 9em
Oval type x 2
1.2W x2
1Vp-p, 752 (RCA pin jack)
500mVrms ( -4dBs ), High Impedance (RCA pin jack)
Low impedance (400Hz when modulated 100%)
(RCA pin jack)
752 (VHF/UHF) Terminal, F-Type Connector
RM-C754-1C
(AA/R6/UM-3 battery x 2)
Design & specification are subject to change without notice.
No.51370

AV-27920
SAFETY PRECAUTIONS
1. The design of this product contains special hardware, many 10. Isolation Check
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.
(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
2. Alterations of the design or circuitry of the products should not be be sure the product is safe to operate without danger of electrical
made. Any design alterations or additions will void the shock.
manufacturer's warranty and will further relieve the manufacturer (1) Dielectric Strength Test ; !
of responsibility for personal injury.or property damage resulting The isolation between the AC primary circuit and all metal parts i
therefrom. exposed to the user, particularly any exposed metal part having a i
3. Many electrical and mechanical parts in the products have return path to the chassis should withstand a voltage of 1100V i
special safety-related characteristics. These characteristics are AC (r.m.s.) for a period of one second. I
often not evident from visual inspection nor can the protection (... . Withstand a voltage of 1100V AC (r.m.s.) to an appliance i
afforded by them necessarily be obtained by using replacement rated up to 120V, and 3000V AC (r.m.s.) to an appliance rated i
components rated for higher voltage, wattage, etc. Replacement 200V or more, for a period of one second.)
parts which have these special safety characteristics are This method of test requires a test equipment not generally found i
identified in the parts list of Service manual. Electrical in the service trade.
components having such features are identified by shading (2) Leakage Current Check i
on the schematics and by (A\) on the parts list in Service Plug the AC line cord directly into the AC outlet (do not use a line ;
manual. The use of a substitute replacement which does not isolation transformer during this check.). Using a “Leakage :
have the same safety characteristics as the recommended Current Tester", measure the leakage current from each exposed j
replacement part shown in the parts list of Service manual may metal part of the cabinet, particularly any exposed metal part i
cause shock, fire, or other hazards. having a return path to the chassis, to a known good earth ground :
4. Use isolation transformer when hot chassis. (water pipe, etc.). Any leakage current must not exceed 0.5mA (
The chassis and any sub-chassis contained in some products are AC (r.m.s.). i
connected to one side of the AC power line. An isolation However, in tropical area, this must not exceed 0.2mA AC
transformer of adequate capacity should be inserted between the (r.m.s.).
product and the AC power supply point while performing any @ Alternate Check Method
service on some products when the HOT chassis is exposed. Plug the AC line cord directly into the AC outlet (do not use a line
5. Don't short between the LIVE side ground and ISOLATED isolation transformer during this check.). Use an AC voltmeter
(NEUTRAL) side ground or EARTH side ground when having 1000 ohms per volt or more sensitivity in the following
repairing. manner. Connect a 15009 10W resistor paralleled by a 0.15 4 F
Some
model's
power
circuit:
is
partly
different
in
the
GND.
The
AC-type
capacitor
between
an
exposed
metal
part
and
a
known
difference
of
the
GND
is
shown
by
the
LIVE
:
(.L)
side
GND,
the
good
earth
ground
(water
pipe,
etc.).
Measure
the
AC
voltage
ISOLATED(NEUTRAL)
:
(+)
side
GND
and
EARTH
:
(@)
side
across
the
resistor
with
the
AC
voltmeter.
Move
the
resistor
GND. Don't short between the LIVE side GND and connection to each exposed metal part, particularly any exposed
ISOLATED(NEUTRAL)
side
GND
or
EARTH
side
GND
and
metal
part
having
a
return
path
to
the
chassis,
and
measure
the
never measure with a measuring apparatus (oscilloscope etc.) the AC voltage across the resistor. Now, reverse the plug in the AC
LIVE
side
GND
and
ISOLATED(NEUTRAL)
side
GND
or
outlet
and
repeat
each
measurement.
Any
voltage
measured
must
‘EARTH side GND at the same time. not exceed 0.75V AC (r.m.s.). This corresponds to 0.5mA AC
If above note will not be kept, a fuse or any parts will be broken, (r.m.s.). :
6. if any repair has been made to the chassis, it is recommended However, in tropical area, this must not exceed 0.3V AC (r.m.s.).
that
the
B1
setting
should
be
checked
or
adjusted
(See
This
corresponds
to
0.2mA
AC
(r.m.s.).
i
ADJUSTMENT OF B1 POWER SUPPLY). i
7. The high voltage applied to the picture tube must conform with AC VOLTMETER |
that specified in Service manual. Excessive high voltage can (HAVING 1000 2/V, i
cause an increase in X-Ray emission, arcing and possible OR MORE SENSITIVITY) ;
component damage, therefore operation under excessive high GOOD |
voltage conditions should be kept to a minimum, or should be padi i
prevented. If severe arcing occurs, remove the AC power i
immediately and determine the cause by visual inspection PLACE THIS PROBE ;
(incorrect installation, cracked or melted high voltage harness, ON EACH EXPOSED i
poor soldering, etc.). To maintain the proper minimum level of soft 15002 10W METAL PART
X-Ray emission, components in the high voltage circuitry f
including the picture tube must be the exact. replacements or 41. High voltage hold down circuit check.
alternatives approved by the manufacturer of the complete After repair of the high voltage hold down circuit, this circuit shail
8 Poe Seek high voltage by drawing an arc. Use a high voltage Be eee Pe Sen:
meter or a high voltage probe with a VTVM. Discharge the picture pees OM TiO Se CIOEe We Heat yates HOKIAO WN Creu: i
tube before attempting meter connection, by connecting a clip :
lead to the ground frame and connecting the other end of the lead This mark shows a fast POWER CORD
through a 10k92 2W resistor to the anode button. operating fuse, the REPLACEMENT WARNING.
9. When service is required, observe the original lead dress. Extra letters indicated below Connecting the line side of
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 manufacturers replacement
components.
No.51370
show the rating. power cord to" @" mark side.

AV-27920
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.
@ (°C bus control utilizes single chip ICs.
Built-in HYPER-SURROUND system.
@ Adoption of the VIDEO STATUS function.
Adoption of the ON/OFF TIMER function.
With 752 V/U in common (F-Type) ANT Terminal.
SLEEP TIMER for setting in real time.
Closed-caption broadcasts can be viewed.
S-VIDEO input terminal for taking best advantage of Super VHS.
Audio Video input terminal.
Variable Audio output terminal.
Built-in MTS system.
DIFFERENCE LIST OF MAIN PARTS
AV-27920(US) — AV-27920(CA)
Parts Name
INST BOOK (FRENCH) ; x LCT0108-001B-A
SVC CENTER LIST x BT-20071B-Q
REGI. CARD BT-51006-1Q x
WARRANTY CARD x BT-52002-1Q
4 No.51370

AV-27920
OPERATING INSTRUCTIONS
e The operating instructions are the same as for C-20910(US&CA)/AV-20920(US&CA)/AV-20921(US&CA) (No.51364),
Therefore, please refer to the C-20910(US&CA)/AV-20920(US&CA)/AV-20921(US&CA)(N0.51364) SERVICE MANUAL for detailed
instructions.
@ REMOTE CONTROL UNIT [RM-C754-1C]
CHANNEL
MUTING VOLUME
© €Ty
MENU exit
on. O
@ 5)
@
@ FRONT PANEL
WMENU — CHANNEL + —— VOLUME + POWER
4OPERATE >
M@ REAR PANEL
No.51370 5
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AV-27920
SPECIFIC
SERVICE
INSTRUCTIONS
DISASSEMBLY PROCEDURE
REMOVING THE REAR COVER
4. Unplug the power supply cord.
2. Remove the 7 screws marked @ and 2 screws marked ® as
shown in Fig.1.
3. Withdraw the REAR COVER toward you.
[CAUTION]
@ When reinstalling the rear cover, carefully push it inward after
inserting the MAIN PWEB into the rear cover groove.
REMOVING THE MAIN PW BOARD
® After removing the rear cover.
1. Pick this side of the MAIN PWB and raise one slightly, take off
the PWB stopper marked © from the cabinet bottom.
2. Pull out the MAIN PWB as it is.
(If necessary, take off the wire clamp and connectors, etc.)
REMOVING THE SPEAKER
@ After removing the MAIN PW board.
1. Remove the 2 screws marked © as shown in Fig.1.
2. Withdraw the speaker backward.
3. Follow the same steps when removing the other hand speaker.
CHECKING THE MAIN PW BOARD
1. To check the back side of the MAIN PW Board.
1) Pull out the MAIN PWB. (Refer to REMOVING THE MAIN
PWB).
2) Erect the chassis vertically so that you can easily check the
back side of the MAIN PW Board.
[CAUTION]
@ When erecting the MAIN PWB, 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.
WIRE CLAMPING AND CABLE TYING
1. Be sure 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.
6 No.51370

AV-27920
FRONT CABINET
CRT SOCKET PWB
(Within MAIN PWB)
SPEAKER
MAIN PWB
ee
Ren
A
eR
NET
MERGE
SEA
OL
Se
SA
ASO
nar
umes
termes
renee
an
gn
REAR COVER
SPEAKER
Fig.1
No.51370

AV-27920
MEMORY IC REPLACEMENT
1. Memory IC
This model use a memory IC.
This memory IC stores data for proper operation of the video and deflection circuits.
When replacing, be sure to use an IC containing this (initial value) data.
2. Memory IC replacement procedure
— ae
Switch off the power and disconnect the power cord from the outlet.
(2) Replace the memory IC
Initial value must be entered into the new IC.
(3) Power on
Connect the power cord to the outlet and switch on the power.
(4) System constant check and setting
1) Simultaneously press the DISPLAY key and VIDEO STATUS key of
the remote control unit.
2) The SERVICE MENU screen of Fig.1 is displayed.
3) While the SERVICE MENU is displayed, again simultaneously press
[SERVICE MENU J
PICTURE SOUND
the DISPLAY and VIDEO STATUS keys to display the Fig.2 SYSTEM GAME
CONSTANT screen. LOW LIGHT HIGH LIGHT
RF AFC CHK
4) Refer to the SYSTEM CONSTANT table and check the setting items.
Where these differ, select the setting item with the MENU UP/DOWN
key and adjust the setting with the MENU LEFT/RIGHT keys. (The
letters of the selected item are displayed in yellow.)
5) After adjusting, release the MENU LEFT/RIGHT key to store the setting
value.
6) Press the EXIT key twice to return the normal screen.
vco( PC BUS CTRL
SELECT BY aij &xiTBY
OPERATE BY Sj (EXIT)
[ SYSTEM CONSTANT
MTS > YES
VARI.OUT > YES
(5) Receive channei setting
Refer to the OPERATING INSTRUCTIONS(USER'S GUIDE) and set the
2 GAME : YES
receive channels (Channels Preset) as described. SURROUND : YES
S-VIDEO > YES
M37272M8-4SP
SELECT BY fal [yi EXIT BY
OPERATE BY ie! EXIT
(6) User settings
Check the user setting items according to Table 2.
Where these do not agree, refer fo the OPERATING INSTRUCTIONS
(USER'S GUIDE) and set the items as described.
(7) SERVICE MENU setting
Verify what to set in the SERVICE MENU, and set whatever is
necessary.(Fig.1) Refer to the SERVICE ADJUSTMENT for setting.
8 No.51370

AV-27920
Setting content
TABLE 1 (System Constant setting)
ee
TABLE 2. (User setting value)
Setting item . Setting value
1. Use remote controller keys
POWER
CHANNEL
CHANNEL PRESET
VOLUME
DISPLAY
SLEEP TIMER
VIDEO STATUS
CLOSED CAPTION
HYPER SURROUND
2. Setting of MENU
TINT
COLOR
PICTURE
BRIGHT
DETAIL
NOISE MUTING
SET VIDEO STATUS
BASS
TREBLE
BALANCE
MTS
TV SPEAKER
SET CLOCK
ON/OFF TIMER
CHANNEL SUMMARY
SET LOCK CODE
AUTO TUNER SETUP
BACKGROUND
CLOSED CAPTION
LANGUAGE
OFF
CH 02
See OPERATING INSTRUCTIONS.
10
OFF
O(OFF)
STANDARD
OFF(CC1/T1)
OFF
CENTER
CENTER
CENTER
CENTER
CENTER
ON
ALL CENTER
CENTER
CENTER
CENTER
STEREO
ON
Unnecessary to set
NO
SET OPTIONALLY
Unnecessary to set
TUNER MODE : AIR
BLACK
CAPTION: CC1 TEXT: T1
ENG
No.51370

AV-27920
SERVICE ADJUSTMENT
ADJUSTMENT PREPARATION:
1. You can make the necessary adjustments for this unit with
either the Remote Control Unit or With the adjustment
tools and parts as given below.
2. Adjustment with the Remote Control Unit is made on the
basis of the initial setting values, however, the new setting
values which set the screen to its optimum condition may
differ from the initial settings.
3. Turn on the power for set and test equipment before use, and
start the adjustment procedures after waiting at least 30
minutes.
4. Make sure that AC power is turned on correctly.
ADJUSTMENT EQUIPMENT
DC voltmeter (or digital voltmeter)
Oscilloscope
Signal generator (Pattern generator) [NTSC]
Remote control unit
. TV audio multiplex signal generator.
. Frequency counter
OnRYWN >
ADJUSTMENT LOCATIONS
VOL+ VOL- CH+ CH MENU
TP-12B
T1341 CW
TP-91 ee
(B1)
TP-E
(1)
Lav IN our _]
S-IN
1C702
5. Unless otherwise specified, prepare the most suitable reception
or input signal for adjustment.
6. Never touch any adjustment parts which are not specified in the
list for this adjustment - variable resistors, transformers,
condensers, etc.
7. Presetting before adjustment.
Unless otherwise specified in the adjustment instructions,
preset the following functions with the remote control unit:
e@ VIDEO STATUS STANDARD
e@ BASS, TREBLE, CENT!
BALANCE ENTER
ADJUSTMENT ITEMS
B1
POWER
WHITE
BALANCE
SUPPLY
(Low
Light)
WHITE
BALANCE
IF
VCO
ead
(High
Light)
RF. AGC SUB BRIGHT
FOCUS SUB CONTRAST
V. SIZE SUB COLOR
H. POSITION SUB TINT
Adjustment items
MTS INPUT
LEVEL check
MTS STEREO
vco
MTS SAP VCO
MTS FILTER check
MTS
SEPARATION
c=]
STEREO[S]
MAIN PWB
CRT SOCKET PWB) '2P
(Within MAIN PWB ASS'Y)
(SOLDER SIDE)
UPPER : FOCUS
LOWER : SCREEN
CRT EARTH
(BRAIDED ASS'Y)
410 No.51370