VESTEL SAT 507D, SAT 507C Service Manual

SAT 507D

SERVICE MANUAL

1999

2

DO NOT CHANGE ANY MODULE UNLESS THE SET IS PLUGGED OFF.

SAT-507D operates between 85 with 265VAC main supply and this voltage level has

THE RISK OF ELECTRICAL SHOCK.

Safety precautions

• Servicing of this satellite receiver should only be carried out by a qualified person.

• DISCONNECT THE RECEIVER’S MAIN SUPPLY BEFORE OPENING THE COVER.

SCART CONNECTIONS

20 18 16 14 12 10 8 6 4 2

21 19 17 15 13 11 9 7 5 3 1

DECODER/VCR SCART TV SCART

1) Audio out R 1) Audio out R

2) Audio in R 2) No connection

3) Audio out L 3) Audio out L

4) Audio ground 4) Audio ground

5) No connection 5) No connection

6) Audio in L 6) No connection

7) No connection 7) No connection

8) Video Int/Ext Switch 8) Video Int/Ext switch

9) No connection 9) No connection

10) No connection 10) No connection

11) Green in 11) Ground

12) No connection 12) No connection

13) No connection 13) No connection

14) No connection 14) No connection

15) No connection 15) No connection

16) No connection 16) No connection

17) Video ground 17) Video ground

18) Ground 18) Ground

19) Video out 19) Video out

20) Video in 20) No connection

21) Ground 21) Ground

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1. INTRODUCTION:

SAT-507D satellite receiver is designed to work for years under proper conditions without
any maintenance and produced with quality control assurance. SAT-507D is a basic model
satellite receiver. The technical information of the receiver will be explained in the
following pages.

2. POWER SUPPLY:

The TOPSWITCH concept is used in power supply. The switching and control circuit is
associated with IC03(TOP223). R251, C201 and D10 are protection circuit of IC03. The
5V regulation is provided by using IC06 (opto-coupler), secondary side components
(C135, D09, R221, R218, R220, IC08, C78, C274) which are coming to reference side of
transformer. IC02 (op-amp) and Q56 with external components generate the LNB voltage.
After the max LNB current or LNB short circuit controls are detected by Q07 and Q08,
the LNB power is cut-off by IC07. The 5V standby switching is made by (Q02). Q12
switches 13/18V. The 22kHz signal generated from IC01 (STV0042A) and it is switched
by Q10, Q11 and after amplified by IC02 than added to LNB voltage via Q56. In order to
reduce the power consumption in standby mode, Q03V switches off the 5V power supply.
When the double LNB inputs tuner is used, the switching of LNB powers is done by Q38,
Q40, Q35, Q39, Q34, Q29, Q25.

3. VIDEO CIRCUIT:

The composite video is first set to a standard level by means of a 64 step gain controlled
amplifier( Pin 17 of IC01 is base band video input ). In the case that the modulation is
negative, an inverter can be switched in. Then energy dispersal is removed by a sync tip
clamping circuit, which is used on all inputs to a video switching matrix, thus making sure
that no DC steps occur when switching video sources. The matrix can be used to feed
video to and from decoders, VCR’s and TV’s. Additionaly all the video outputs are
tristate type (high impedance mode is supported), allowing a simple parallel connections
to the scarts. After the video processing is finished, the external video enter to pin18 of
IC05. The sync of video is generated by R121, C45, R269 , C275, C46, R123, R227,
C177 and send to pin12 of IC07. According to decision of video, the selected video
(internal/external) is sent to the video outputs( scarts, modulator etc.) at pin16 of IC05.

4. SOUND CIRCUIT:

The two audio channels are totally independent except for the possibility given to output
on both channels only one of the selected input audio channels. To allow a very cost
effective application, each channel uses PLL demodulation. Neither external complex
filter nor ceramic filters are needed. The frequency of the demodulated subcarrier is
chosen by a frequency synthesizer which sets the frequency of the internal local oscillator
by comparing its phase with the internally generated reference. When the frequency is
reached, the microprocessor switches in the PLL and the demodulation starts. At any
moment the microprocessor can read from the device (watchdog registers) the actual
frequency to which the PLL is locked. It can also verify that a carrier is present at the
wanted frequency (by reading AMPLK status bit) thanks to a synchronous amplitude
detector, which is also used for the audio input AGC. In order to maintain constant
amplitude of the recovered audio regardless of variations between satellites or subcarriers,
the PLL loop gain may be programmed from 56 values. Any frequency deviation can be
accomodated (from ±30kHz till ±400kHz). In the typical application, the

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STV0042Aoffers two audio de-emphasis 75ms and 50ms. Adynamic noise reduction
system (ANRS) is integrated into the STV0042A using a low pass filter, the cut-off
frequency of which is controlled by the amplitude of the audio after insertion of a band­pass filter. Two types of audio outputs are provided : one is a fixed 1VRMS and the other
is a gain controlled 2VRMS max. The control range being from +12dB to -26.75dBwith

1.25dBsteps. This output can also be muted. A matrix is implemented to feed audio to and
from decoders VCR’s and TV’s. Noise reduction system and de-emphasis can be inserted
or by-passed through bus control. Also all the audio outputs are tri-state type (high
impedance mode is supported), allowing a simple parallel connections to the scarts . The
audio outputs are pin4 of IC01( audio R ) and pin7 of IC07( audio L ).

5. CONTROL CIRCUIT:

The satellite receiver is controlled by the microcontroller IC07. All switching and PLL
control are accomplished by this IC. IC09 (EEPROM) is used as the memory IC for
reading/writing. Infrared signals sent by the R/C are received and sent to IC06 by IR1
infrared module. For tact switches and 4x7-Segment display (common anode) there’s
multiplexed control. The 60Hz signal is generated at pin1 of IC07 but this is optional.

6. OTHERS:

A 22kHz tone is generated for LNB control. It is selectable by bus control and available
on one of the two pins connected to the external video de-emphasis networks. By means
of the I2C bus there is the possibility to drive the ICs into a low power consumption mode
with active audio and video matrixes. Independently from the main power mode, each
individual audio and video output can be driven to high impedance mode.

5

IC DESCRIPTIONS AND INTERNAL BLOCK DIAGRAMS

IC NAME PAGE NO

• 87C52 ........................................................................................6

• STV0042 ...................................................................................9

• LC74763.................................................................................... 12

• 24C32 ........................................................................................15

• LM358.......................................................................................17

•

CQY80NG................................................................................... 19

•

TOP223Y…………………………………………………………………21

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80C52
MICROCONTROLLER

GENERAL DESCRIPTION:

The 80C52 is a general purpose microcontroller. It is intended for use as the central
control mechanism in this satellite receiver. The 80C52 is a member of the 80C51
microcontroller family.

FEATURES:

• Power control modes

• 256 bytes of RAM

• 8 Kbytes of ROM

• 32 programmable I/O lines

• Three 16 bit timer/counters

• 64 K program memory space

• 64 K data memory space

• Fully static design

• 0.8µ CMOS process

• Boolean processor

• 6 interrupt sources

• Programmable serial port

PINNING

1. T2/P1.0 60Hz Output

2. T2EX/P1.1 AV Input (decoder/VCR scart pin8)

3. P1.2

4. P1.3

5. P1.4

6. P1.5 22Khz control pin

7. P1.6

8. P1.7

9. RST

10. P3.0/RXD

11. P3.1/TXD

12. P3.2/INT0 Horizontal Synch. Input

13. P3.3/INT1 Infrared Input

14. P3.4/T0

15. P3.5/T1 LNB Short Circuit Control Input

16. P3.6/WR LNB Power Output

17. P3.7/RD Standby

18. XTAL2 oscillator output

19. XTAL1 oscillator input; 12 MHz crystal

20. Vss ground supply input

21. P2.0/A9 7 Segment Display Driver

22. P2.1/A8 7 Segment Display Driver

7

23. P2.2/A10 7 Segment Display Driver

24. P2.3/A11 7 Segment Display Driver

25. P2.4/A12 7 Segment Display Driver/Keypad Input

26. P2.5/A13 7 Segment Display Driver/Keypad Input

27. P2.6/A14 7 Segment Display Driver/Keypad Input

28. P2.7/A15 Keypad Output

29. PSEN

30. ALE

31. EA

32. P0.7/A7 H/V

33. P0.6/A6 CS

34. P0.5/A5 SDA

35. P0.4/A4 SCL

36. P0.3/A3 7 Segment Display Driver

37. P0.2/A2 7 Segment Display Driver

38. P0.1/A1 7 Segment Display Driver

39. P0.0/A0 7 Segment Display Driver

40. Vcc +5V supply voltage input