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SERVICE MANUAL
SM-1 Chassis
28"CTV
SM-1 Chassis 28" Service Manual
SM-1 Chassis 28" Service Manual
Contents
Technical Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
Recommendation for service repairs . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
Scart pin descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
Component description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Adjustments procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
Fault tracing diagram -power supply . . . . . . . . . . . . . . . . . . . . . . . . . . .12
Description of the circuit
TDA4605 (Power Supply) . . . . . . . . . . . . . . . . . . . . . . .13
CTV352S (Micro controller) . . . . . . . . . . . . . . . . . . . . .15
PCF8582A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
TDA8361/TDA8362 (Analog operation) . . . . . . . . . . . . . . . . . . .18
TDA9821 (Dual Channel - Sound demodulator) . . . .22
TDA9820 (Sound demodulator
multi standard version) . . . . . . . . . . . . . . . .24
TDA9840 (Stereo / Dual sound processor) . . . . . . . . .25
TDA8425 (Hi-Fi Stereo audio processor) . . . . . . . . . . .27
TDA2616 (Hi-Fi audio power) . . . . . . . . . . . . . . . . . . . .28
TDA4661 (Base band delay - line) . . . . . . . . . . . . . . .30
TDA8395 (Secam decoder) . . . . . . . . . . . . . . . . . . . .32
TDA3866 (Quaji - split sound processor) . . . . . . . . . . .33
SAA7283 (Terrestrial digital sound decoder) . . . . . . .35
TDA4470 (Multistandard video -
IF with FPLL demodulation) . . . . . . . . . . . . .40
TDA3654 (Vertical circuit) . . . . . . . . . . . . . . . . . . . . . .45
SAA5231 (Teletext video processor) . . . . . . . . . . . . . .48
SAA5243 (Teletext circuit) . . . . . . . . . . . . . . . . . . . . . .49
BUZ90 (Power fet) . . . . . . . . . . . . . . . . . . . . . . . . . .51
BUH515D (High voltage fastswitching transistor) . . . .53
BF869/871 (NPN Epitaxial planar RF transistors) . . . . . .56
Remote Sensor circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .58
Oscilloscope signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .59
Pin voltages of IC's . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .60
Exploded views . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .62
Chassis replacement
parts list . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .65
3
SM-1 Chassis 28" Service Manual
TECHNICAL DATA
CRT PANEL
Visible Picture 66 cm
Deflection Angle 110o
Vertical Frequency 50Hz
Horizontal Frequency 15.625Hz
ELECTRONIC
Program Number 70+1 AV
Teletext S. Text (Flof Text off)
Tuner Cable tuner - 8 MHz spacing for Hyper Band
TV System European CCIR system
Music Power 2x5Watt Rms 10% distortion
CONNECTIONS
Euro AV Socket Include
MAIN STAGE
Mains Voltage 165-260VAC
Mains Frequency 50Hz
Power Consumption 115W
In Stby Mode ~15W
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SM-1 Chassis 28" Service Manual
RECOMMENDATION FOR SERVICE REPAIRS
1- Use only original spare parts. Only use components volve a shock hazard from the receiver.
with the same specifications for replacement. Servicing should not be attempted by anyone who
2- Original fuse value only should be used. is not thoroughly familiar with the precautions
3- Main leads and connecting leads should be chec- necessary when working on high voltage equip-
ked for external damage before connection. ment.
Check the insulation. Perfectly discharge the high potential of the pictu-
4- Parts contributing to the safety of the product must re tube before handling the tube. The picture tube
not be damaged or obviously unsuitable. is highly evacuated and if broken.
This is valid especially for insulators and insulating Glass fragments will be violently expelled.
parts. Always discharge the picture tube anode to the re-
5- Thermally loaded solder pads are to be sucked off ceiver chassis to keep of the shock hazard before
and re-soldered. removing the anode cap.
6- Ensure that the ventilation slots are not obstructed. 8- Keep wire away from the high voltage or high tem-
7- Potentials as high as 25 KV are present when this re- perature components.
ceiver is operating. Operation of the receiver 9- When replacing a wattage resistor in circuit board,
outside the cabinet or with back cover removed in- keep the resistor 10 mm away from circuit board.
HANDLING OF MOS
CHIP COMPONENTS
MOS circuit requires special attention with regard to til they are used. Most components must never be
static charges. Static charges may occur with any stored in styropor materials or plastic magazines.
highly insulating plastics and can be transferred to 2- Persons have to rid themselves of electrostatic char-
persons wearing clothes and shoes made of synthetic ges by touching MOS components.
materials. Protective circuits on the inputs and outputs 3- Hold the component by the body touching the ter-
of mos circuits give protection to a limited extend only minals.
due to time of reaction.
4- Use only grounded instruments for testing and pro-
Please observe the following instructions to protect the cessing purposes.
components against damage from static charges. 5- Remove or connect MOS ICs when operating volta-
1- Keep mos components in conductive package un- ge is disconnected.
X-RAY RADIATION
PRECAUTION
1- Excessive high voltage can be produce potentially voltage be recorded as a part of the service re-
hazardous X-RAY radiation. To avoid such hazard, cord. It is important to use an accurate and reliab-
the high voltage must not be above the specified li- le high voltage meter.
mit. The nominal value of the high voltage of this re- 2- The primary source of X-RAY radiation in this TV re-
ceiver is 25KV at zero beam current (minimum ceiver is the picture tube. For continued X-RAY radi-
brightness) under 220V AC power source. The high ation protection, the replacement tube must be
voltage must not under any circumstance, exceed exactly the same type tube as specified in the part
30KV. It is recommended the reading of the high list.
5
SM-1 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
1 3 5 7 9 11 13 15 17 19 21
2 4 6 8 10 12 14 16 18 20
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SM-1 Chassis 28" Service Manual
POWER CORD
SAW FILTER
IR SENSOR
VOLTAGE REGULATOR
ON/OFF SWITCH
LINE FILTER
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
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SM-1 Chassis 28" Service Manual
SERVICE ADJUSTMENT
AND ALIGNMENTS
HIGH VOLTAGE TEST
There is no high voltage adjustment component on the chassis. Changing of +145
depends on the supply voltage. If it's necessary to measure high voltage.
1- Connect the probe of high voltage tester to the anode of CPT.
2- Adjust contrast and brightness to minimum.
3- Measure the high voltage as 27 KV for 25 "and 28" screen size.
4- For maximum brightness, high voltage regulation should be 2KV dc max.
AGC ADJUSTMENT
1- Apply Philips pattern signal which is 60 dB uV to the RF input.
2- Adjust VR182 until find a picture without snowy.
VERTICAL ADJUSTMENT
1- Apply Philips pattern.
2- Cut down vertical amplitude with VR 576.
3- Center picture with three position key.
4- Make vertical adjustment with VR576 that will see lower and top lines of picture.
HORIZONTAL ADJUSTMENT
1- Apply Philips pattern signal.
2- Center the picture while shifting to right and left with VR 181.
STEREO / DUAL ADJUSTMENT
1- Connect oscilloscope 14 PIN out of IC901 (TDA9840).
2- Apply one channel signal with stereo publication.
3- Adjust sound signal of 1 KHz and 3KHz by means of VR326 that the difference
between should be minimum.
TELETEXT ADJUSTMENT
1- Apply one channel signal with teletext publication.
2- Cut video signal which gone IC730.
3- Stop horizontal shifting of picture with VC 726.
4- Again connect video signal to IC730 and check picture.
ADJUSTMENT OF SUPPLY VOLTAGE
1- Apply Philips pattern signal.
2- Make the volume, brightness and contrast adjustment to minimum.
3- Adjust the supply voltage on the PIN cathode of D125 as Vsys = 145 + 0.5 by
using VR101.
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SM-1 Chassis 28" Service Manual
FOCUS ADJUSTMENT
Adjust the thickness of lines until being minimum, by focus trimpot on the EHT trans-
former. By using crosshatch or multi-burst test pattern.
WHITE BALANCE ADJUSTMENT
1- Apply Philips pattern.
2- Adjust VR52, VR54 are trimpots to middle position and VR51, VR53 and VR55 are
trimpots to minimum.
3- Adjust BRT, CONT, COL to min.
4- Adjust at lower grey bar of Philips pattern by screen trimpot that two bars should
be seen.
5- Increase BRT control little and adjust white balance by using VR51, VR53, VR55 with
eyes.
6- Apply white pattern. Settle screen probe of minolta, adjust Y = 5 nits with bright-
ness.
7- Increase contrast until adjust X = Y = 270 - 276 nits by means of VR52, VR54.
8- Bring contrast to minimum. Adjust X = Y = 270 - 276 nts at Y = 5 nits by means of
VR51, VR53, VR55.
9- Check white balance at high and low contrast level. Again make adjustment if it's
necessary.
AFT ADJUSTMENT
1- Disconnect the if output tuner from if input.
2- Apply 38.9 MHz signal with PM5518 Philips pattern generator to IF input.
3- Connect a digital voltmeter to AFT PIN of IC476.
4- Adjust T181 coil until the voltage of IC476 is being 2.5Vdc.
5- Connect the IF input which input is disconnected in the beginning.
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SM-1 Chassis 28" Service Manual
BLOCK DIAGRAM
10
SM-1 Chassis 28" Service Manual
POWER CIRCUIT
CONTROLLER CIRCUIT
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SM-1 Chassis 28" Service Manual
FAULT TRACING DIAGRAM - POWER SUPPLY
SW DEFECTIVE, + 145V C 101, C 102 YES Fuse (Em-103 LEVEL IS WRONG
D 101 defective
R 101, Q 101
NO
open and short Voltage at drain
Q101
circuit
YES
R109 Voltage at IC 101
pin-3
<1V
YES Start-up
D 104 Voltage IC 101(6)
pin-3
<8V
Start-up
Q101 Voltage varies
ca. 8V
IC 101
Measure +145V
+145V
adjustable
VR101, R107
with
VR101
Control range of
12 switched-mode
power supply
SM-1 Chassis 28" Service Manual
Power Supply With
TDA4605
The IC TDA 4605 controls the MOS power transistor and performs all necessary regulation and moni-
toring functions in free running flyback converters.
FEATURES
l Overload protection
l Burst operation under short circuit conditions
l Loop error protection
l Switch-off if line voltage is too low
l Line voltage compensation of overload point
l Soft start for quite start up
l Chip over temperature protection
l On-chip parasitic transformer oscillation suppression circuit
TDA 4605-3
PINNING PIN VOLTAGE
ST-BY NORM.
1 Information Input Concerning Secondary Voltage 0.4V 0.4V
2 Information Input Regarding the Primary Current 1V 1.2V
3 Input for Primary Voltage Monitor 2.1V 2V
4 Ground 0V 0V
5 Output 0.8V 8V(10Vpp)
6 Supply voltage Input 12V 12.8V
7 Input for Soft-Start and Integrator Circuit 1.1V 1.9V
8 Input for the Feedback of the Oscillator 0.3V 0.4V
TDA4605
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SM-1 Chassis 28" Service Manual
Pin Definitions and Functions
Pin No. Function
1 Information Input Concerning Secondary Voltage
By comparing the regulating voltage - obtained trom the regulating winding of the trans-
former - with the internal reference voltage, the output impulse width on pin 5 is adjusted
to the load of the secondary side (normal, overload, short-circuit, no load).
2 Information Input Regarding the Primary Current
The primary current rise in the primary winding is simulated at pin 2 as a voltage rise by me-
ans of external RC-element. When a voltage level is reached thats derived from the regu-
lating voltage at pin 1, the output impulse at pin 5 is terminated. The RC-element serves
to set the maximum power at the overload point set.
3 Input for Primary Voltage Monitoring
In the normal operation V3 is moving between the thresholds V3H and V3L (V3H > V3 >
V3L)-
V3 < V3L: SMPS is switched OFF (line voltage too low).
V3 > V3H : Compensation of the overload point regulation (controlled by pin 2)
starts at V3H : V3L = 1.7.
4 Ground
5 Output
Push-pull output provides