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SERVICE MANUAL
100 Hz Chassis
28" CTV
100 Hz. Chassis 28" Service Manual
Contents
Technical Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
Recommendation for service repairs . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
Component description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Scart pin descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
Exploded views . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
Specifications of the connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
Video - Board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
Circuit Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
Component Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
TDA4780 (RGB video processor) . . . . . . . . . . . . . . . . . . . .18
TDA4665 (Base band delay - line) . . . . . . . . . . . . . . . . . . .23
TDA9143 (I2C-Bus Controlled) . . . . . . . . . . . . . . . . . . . . . . .26
SAA4961 (Multistandard Comb Filter) . . . . . . . . . . . . . . .33
TDA4470B (Multistandard video -
IF and quasi parallel sand processing) . . . . . . .36
TDA9151B (Programmable deflection controller) . . . . . . .40
TDA8540 (4x4 video switch matrix) . . . . . . . . . . . . . . . . . .46
TDA8351 (DC-coupled vertical deflection circuit) . . . . . .48
TDA9875A (Digital TV sound processor) . . . . . . . . . . . . . . . .50
TDA2616 (2x12W Hi-Fi audio power) . . . . . . . . . . . . . . . . .57
TDA4605 (Control IC for SMPS) . . . . . . . . . . . . . . . . . . . . .59
TDA6111Q (Video output amplifier) . . . . . . . . . . . . . . . . . . .61
M27C2001 (2 megabit UV eprom) . . . . . . . . . . . . . . . . . . . .64
ST24C16 (Serial 16K eeprom) . . . . . . . . . . . . . . . . . . . . . . .67
SAA7710 (Dolby Pro Logic Surround) . . . . . . . . . . . . . . . . .69
SAA7053A (Stereo BTL audio output) . . . . . . . . . . . . . . . . . .73
SDA5250 (Microcontroller unit) . . . . . . . . . . . . . . . . . . . . .75
Oscilloscope signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .78
3
100 Hz. Chassis 28" Service Manual
TECHNICAL DATA
CRT PANEL
Visible Picture 66 cm
Deflection Angle 110o
Vertical Frequency 100Hz
Horizontal Frequency 31.250Hz
ELECTRONIC
Program Number 100+2AV +SVHS
Teletext 8 pages fast text (Top text optional)
Tuner PLL
TV System European CCIR system
Music Power 2x8Watt Rms 10% distortion
CONNECTIONS
Euro AV Socket Include
SVHS Include
MAIN STAGE
Mains Voltage 165-260VAC
Mains Frequency 50Hz
Power Consumption 145W
In Stby Mode 2W
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100 Hz. Chassis 28" Service Manual
RECOMMENDATION FOR SERVICE REPAIRS
1- Use only original spare parts. Only use compo- Always discharge the picture tube anode to
nents with the same specifications for repla- the receiver chassis to keep of the shock ha-
cement. zard before removing the anode cap.
2- Original fuse value only should be used. 8- Keep wire away from the high voltage or high
3- Main leads and connecting leads should be temperature components.
checked for external damage before con- 9- When replacing a wattage resistor in circuit
nection. board, keep the resistor 10 mm away from cir-
Check the insulation. cuit board.
4- Parts contributing to the safety of the product 10) Discharging of the picture tube is effected
must not be damaged or obviously unsuitab- only by the connection point of the aquadaq
le. coating the picture tube.
This is valid especially for insulators and insula- 11) When carrying out repairing process at con-
ting parts. trol unit do not approach too near to the pic-
5- Thermally loaded solder pads are to be suc- ture tube in order to avoid any charge trans-
ked off and re-soldered. fer.
6- Ensure that the ventilation slots are not obst- 12) Measurements within the primary circuit of the
ructed. switched mode power supply are allowed to
7- Potentials as high as 31 KV are present when be carried out only when using potential-free
this receiver is operating. Operation of the re- measuring equipment. Voltages indicated for
ceiver outside the cabinet or with back cover this circuit are based on mains voltage refer-
removed involve a shock hazard from the re- ence level.
ceiver. 13) The defined local radiation dosage accord-
Servicing should not be attempted by anyo- ing to the x-ray radiation regulation is given by
ne who is not thoroughly familiar with the pre- the specific type of the picture tube and the
cautions necessary when working on high maximum permissible EHT voltage. The EHT
voltage equipment. voltage must not exceed the maximum value
Perfectly discharge the high potential of the of 31kv.
picture tube before handling the tube. The 14) When the repair process is carried out 12 V
picture tube is highly evacuated and if bro- line voltage should not be interrupted
ken. because video output stage is endangered
Glass fragments will be violently expelled. by the interruption of 12 V line voltage.
HANDLING OF MOS CHIP COMPONENTS
MOS circuit requires special attention with regard ge until they are used. Most components must
to static charges. Static charges may occur with never be stored in styropor materials or plastic
any highly insulating plastics and can be transfer- magazines.
red to persons wearing clothes and shoes made 2- Persons have to rid themselves of electrostatic
of synthetic materials. Protective circuits on the charges by touching MOS components.
inputs and outputs of mos circuits give protection 3- Hold the component by the body touching the
to a limited extend only due to time of reaction. terminals.
Please observe the following instructions to pro- 4- Use only grounded instruments for testing and
tect the components against damage from sta- processing purposes.
tic charges. 5- Remove or connect MOS ICs when operating
1- Keep mos components in conductive packa- voltage is disconnected.
5
100 Hz. Chassis 28" Service Manual
X-RAY RADIATION PRECAUTION
1- Excessive high voltage can be produce poten- ded as a part of the service record. It is impor-
tially hazardous X-RAY radiation. To avoid such tant to use an accurate and reliable high vol-
hazard, the high voltage must not be above tage meter.
the specified limit. The value of the high volta-
ge of this receiver is 30KV at zero beam current 2- The primary source of X-RAY radiation in this TV
(minimum brightness) under 220V AC power receiver is the picture tube. For continued X-
source. The high voltage must not under any RAY radiation protection, the replacement tu-
circumstance, exceed 31.5KV. It is recommen- be must be exactly the same type tube as spe-
ded the reading of the high voltage be recor- cified in the part list.
SOLDERING PROCESS
1) SMD Components (Surface component. Terminals of the SMD components
must not contact directly to the soldering iron.
Mounted Device)
2)PLCC Components
Desoldering: Desoldering:
Heat up the component from its terminals for 2 or Heat up the terminals of PLCC component for 3
3 seconds with a soldering iron and afterwards ta- or 5 seconds by means of SMD soldering iron and
ke out the component carefully by means of the PLCC desoldering pair (angle 900C, Leg: 24mm).
tweezers. Remove superfluous solder at the solder Take out PLCC component carefully by slightly
surfaces of the components place at pcb by me- turning of desoldering tweezers.
ans of desoldering strand or suction de-solder
equipment. Never force the component for re-
moving without heating the terminals sufficiently. Soldering:
Unsoldered components should not be used for Remove superfluous solder at the solder surfaces
once more. of the components placed on pcb by means of
de-soldering iron or suction de-solder equipment.
Apply flux with low grease content. Place PLCC
Soldering: device on the soldering surface and take care
Place the component properly to its position by for its correct placement. Secure diagonally by
means of tweezers and solder one side of the means of two soldering joints. Apply soldering
component. Then check out the position of the paste along PLCC pins. Short circuits which may
component and be sure if it is soldered to the occure during soldering process have to be
right place and then solder other side of the removed immediately with a soldering iron.
6
100 Hz. Chassis 28" Service Manual
POWER CORD
SAW FILTER
IR SENSOR
VOLTAGE REGULATOR
ON/OFF SWITCH
LINE FILTER
HEADPHONE
RELAY
PTC
NPN TRANSISTOR
PNP TRANSISTOR
CERAMIC FILTER
COIL
LINEARITY COIL
FUSIBLE RESISTOR
IW METAL OXIDE RESISTOR
1/2W METAL OXIDE RESISTOR
1/4 OR 1/6W CARBON FILM RESISTOR
CERAMIC CAPACITOR /POLYESTER CAPACITOR
ELECTROLYTIC CAPACITOR
DIODE
ZENER DIODE
SWITCH JUMPER
NET (INPUT)
NET (OUTPUT)
TACT SWITCH
7
100 Hz. Chassis 28" Service Manual
8
100 Hz. Chassis 28" Service Manual
SPECIFICATIONS OF THE CONNECTOR
(EURO SCART)
I- Audio output 1. right channel 0.5 VRMS/<1 k 0
2- Audio input 1. right channel 0.5 VRMS (connected to No.6)
3- Audio output 2. left channel 0.5 VRMS (connected to No.1)
4- GND (audio)
5- GND
6- Audio input 2. left channel 0.5 VRMS/>10k 0
7- RGB input, blue (B)
8- Switch signal video (status)
9- GND
10- Reserved for clock signals (not connected)
11- RGB input, green (G)
12- Reserved for remote control (not connected)
13- GND
14- GND switch signal RGB
15- RGB input, red (R)
16- Switch signal RGB
17- GND (video)
18- GND
19- Video output 1 Vpp/75 ohm
20- Video input 1 Vpp/75 ohm
21- Shield
20 18 16 14 12 10 8 6 4 2
21 19 17 15 13 11 9 7 5 3 1
9
100 Hz. Chassis 28" Service Manual
BLOCK DIAGRAM
10
100 Hz. Chassis 28" Service Manual
VIDEO BOARD
11
100 Hz. Chassis 28" Service Manual
CIRCUIT DESCRIPTION
1- MAIN SUPPLY UNIT The main switched-mode power supply unit inclu-
ding a fly back converter controlled by an opto-
A-General Description electronic coupler consists the driving IC TDA 4605-3
In order to obtain 2W power at standby mode, two and the switching transistor BUZ91. The following
separate circuits are used. One for standby power operating voltages are delivered by the transformer
supply and another for switched-mode power sup- of the switched-mode power supply after their recti-
ply. fication.
The standby supply unit consists of a push-pull con-
145Vdc : +B Line is a direct output voltage.
verter (Q803 and Q804) producing the required 5V
operating voltage by full wave rectification. This vol- 33VDC : +F Delivered from 145vdc
tage is stabilised by means of D807 and D808. This +16Vdc : +H Horizontal driver voltage.
voltage runs the