JVC TU-DB1SU Service Manual

YA224200411
SERVICE MANUAL
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TU-DB1SU
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TABLE OF CONTENTS
2 SPECIFIC SERVICE INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
3 DISASSEMBLY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6
4 ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-9
5 TROUBLESHOOTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-10
COPYRIGHT © 2004 Victor Company of Japan, Limited
No.YA224
2004/11
SPECIFICATION
Items Contents
Dimensions ( W × H × D ) 28.0cm × 4.0cm × 18.5cm
Mass 1.3kg
Broadcasting System DVB-T 2k & 8k
RF System PAL
Video System PAL
Audio System MPEG Layer I & II , 32kHz / 44.1kHz / 48kHz , Single / Dual channels , Stereo & joint stereo
Teletext System Digital Teletext
Channel Memory Number 200ch
Channel Coverage 47.0MHz to 858MHz
Power Requirements DC6V, AC adaptor : AC100V to AC240V, 50Hz / 60Hz
Antenna Input 75 unbalanced, PAL type × 1 (5V DC active antenna supply) TV Output 75 unbalanced, PAL type × 1 (Loop through)
Video 1V (p-p) , 75
TV(SCART-1) Terminal (Input/Output)
VCR(SCART-2) Terminal (Input/Output)
Digital Audio Output SPDIF coaxial × 1 Remote Control Unit VE-30031949 (RM-C1890S), (AA/R06 dry battery × 2)
Design & specifications are subject to change without notice.
Audio 500mV (rms) (-4dBs), 10k min
RGB / Video 1V (p-p) , 75
S-Video
RGB / Video 1V (p-p) , 75
S-Video
Y : 1V (p-p) positive, 75
C : 0.286V (p-p) (burst signal), 75 Video 1V (p-p) , 75 Audio 500mV (rms) (-4dBs), 10k min
Y : 1V (p-p) positive, 75
C : 0.286V (p-p) (burst signal), 75
1-2 (No.YA224)
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 ADJUSTMENT OF B1 POWER SUPPLY).
(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 10k
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 1000 ohms per volt or more
sensitivity in the following manner. Connect a 1500 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
1500 10W
GOOD EARTH GROUND
ON EACH EXPOSED ME TAL PAR T
(No.YA224)1-3
SECTION 2
SPECIFIC SERVICE INSTRUCTIONS

2.1 INTRODUCTION

• TU-DB1SU is a DVB-T set-top box capable of decoding MPEG coded source. It outputs CVBS, RGB and Y/C analog video and left
-right analog audio. TU-DB1SU also has digital audio output.
• The tuner is capable of getting both digital broadcasts. The tuner is capable of receiving both VHF and UHF horizontal bands. The tuning is available through the digitally controlled I2C bus (PLL).

2.2 FUNCTIONS

[FRONT]
[REAR]
1
3 4
2
5
1 Standby button(Power) 2 Power Indicator 3 Program up button 4 Program down button 5 REMOTE CONTROL UNIT Sensor
RS 232 TV OUT ANTENNA TV VCR SPDIF 6V DC
1
3
2
4
5 6 7
1-4 (No.YA224)
1 RS 232 Terminal 2 TV Output 3 Antenna Terminal 4 TV (Scart-1) Terminal (21-pin Euro connector) 5 VCR (Scart-2) Terminal (21-pin Euro conector) 6 SPDIF Terminal 7 DC 6V Input Terminal

2.3 21-PIN EURO CONNECTOR (SCART SOCKET) : PL201 / PL601

[Pin assignment]
20 18 16 14 12 10 8 6 4 2
21 19 17 15 13 11 9 7 5 3 1
Pin
PL201 : TV SCART SOCKET PL601 : VCR SCART SOCKET
Description Description
1 Audio Right Output Audio Right Output
2 Audio Right Input Audio Right Input
3 Audio Left Output Audio Left Output
4GND GND
5GND GND
6 Audio Left Input Audio Left Input
7 BLUE Output BLUE Output
8 Function Switching Output Function Switching Input
9GND GND
10 Not connected No Connection
11 GREEN Output GREEN Output
12 Not connected No Connection
13 GND GND
14 GND GND
15 RED Output / C Output RED Output / C Output
16 Fast Blanking Output No Connection
17 GND GND
18 GND GND
19 CVBS Output / Y Output CVBS Output / Y Output
20 CVBS Input CVBS Input
21 GND GND
(No.YA224)1-5
SECTION 3
DISASSEMBLY

3.1 DISASSEMBLY PROCEDULE

3.1.1 TOP COVER
(1) Unplug the connecting the AC adaptor. (2) Remove the 4 the Rubber Foot . (3) Remove the 5 screws [A] . (4) Withdraw the TOP COVER.
3.1.2 MAIN PWB
• Take out the TOP COVER. (1) Remove the 1 screw [B] . (2) Slightly raise the both sides of the MAIN PWB by hand and
withdraw the MAIN PWB backward.
[CAUTION]
If necessary, take off the wire clamp, connectors etc. Be careful enough when developing a MAIN PWB.
3.1.3 FRONT CONTROL PWB
• Take out the TOP COVER. (1) Remove the 2 screws [C]. (2) Remove the FRONT CONTROL PWB.
3.1.4 DAUGHTER PWB
• Take out the TOP COVER. (1) Remove the 2 screws [D]. (2) Remove the DAUGHTER PWB.
3.1.6 CHECKING THE PW BOARD
• To check the back side of the PW Board. (1) Pull out the PW Board. (Refer to REMOVING THE MAIN
PWB).
(2) Erect the PW Board vertically so that you can easily check
the back side of the PW Board.
[CAUTION]
• When erecting the PW Board, 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.
3.1.7 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.
3.1.5 BACK COVER
• Take out the TOP COVER. (1) Raise up the both sides and withdraw the BACK COVER.
1-6 (No.YA224)
FRAME L
AC ADAPTOR
TOP COVER
FRAME R
BACK COVER
MAIN PWB
LED LENS
LED FRAME
D
(x2)
PROGRAM DOWN/UP BUTTONS
DAUGHTER PWB
B
(x1)
C
(x2)
FRONT CONTROL PWB
SENSOR LENS
SENSOR LENS HOLDER
BOTTOM COVER
STANDBY BUTTON
A
(x2)
RUBBER FOOT
(x2)
A
(x2)
A
(x1)
RUBBER FOOT
(x2)
(No.YA224)1-7

3.2 REPLACEMENT OF CHIP COMPONENT

3.2.1 CAUTIONS
(1) Avoid heating for more than 3 seconds. (2) Do not rub the electrodes and the resist parts of the pattern. (3) When removing a chip part, melt the solder adequately. (4) Do not reuse a chip part after removing it.
3.2.2 SOLDERING IRON
(1) Use a high insulation soldering iron with a thin pointed end of it. (2) A 30w soldering iron is recommended for easily removing parts.
3.2.3 REPLACEMENT STEPS
1. How to remove Chip parts
2. How to install Chip parts
[Resistors, capacitors, etc.]
(1) As shown in the figure, push the part with tweezers and
alternately melt the solder at each end.
(2) Shift with the tweezers and remove the chip part.
[Transistors, diodes, variable resistors, etc.]
(1) Apply extra solder to each lead.
SOLDER
SOLDER
[Resistors, capacitors, etc.]
(1) Apply solder to the pattern as indicated in the figure.
(2) Grasp the chip part with tweezers and place it on the
solder. Then heat and melt the solder at both ends of the chip part.
[Transistors, diodes, variable resistors, etc.]
(1) Apply solder to the pattern as indicated in the figure. (2) Grasp the chip part with tweezers and place it on the
solder.
(3) First solder lead A as indicated in the figure.
(2) As shown in the figure, push the part with tweezers and
alternately melt the solder at each lead. Shift and remove the chip part.
NOTE :
After removing the part, remove remaining solder from the pattern.
1-8 (No.YA224)
A
B
C
(4) Then solder leads B and C.
A
B
C
SECTION 4
ADJUSTMENT
This service manual does not describe ADJUSTMENT.
(No.YA224)1-9
SECTION 5
TROUBLESHOOTING
This service manual does not describe TROUBLESHOOTING.
1-10 (No.YA224)
Victor Company of Japan, Limited AV & MULTIMEDIA COMPANY VIDEO DISPLAY CATEGORY 12, 3-chome, Moriya-cho, kanagawa-ku, Yokohama, kanagawa-prefecture, 221-8528, Japan
(No.YA224)
Printed in Japan
VPT
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