Main Board (16Mb07 E3 ) - VESTEL SAT 3600 Service Manual

SERVICE MANUAL
The switching of LNB supply voltage is done here. 18V and 22V outputs of transformer
switched by Q1, Q2 and H/V output of STV299 (TU400). By this way overheating and
unnecessary power consumption of Q5 (BD235) that regulates the LNB supply is prevented.
22kHz tone which is needed for DiSEqC signals, is generated at pin15 (Alps-TU400) or pin12
(Sharp-TU400) of STV0299 in tuner 22KHz is added to LNB supply here via LM358N (IC4).
16PW07-3 Power Board
Voltage
LNB_SUPPLY_IN (13V, 18V)
+30V
+12V
+3V3
Voltage
LNB_SUPPLY_IN (13V VER)
LNB_SUPPLY_IN (18V HOR)
+30V
+12V
+3V3
+2V5

MAIN BOARD (16MB07 E3 )

The main board contains two parts: Front-end and Back-end. The digital signal is
demodulated in Front-end and then decoded in Back-end. Analog signals are processed in
different part.
The tuner (TU400 Alps or Sharp) is capable of getting both digital broadcasts. After the
modulated signals (I, Q outputs) receive from tuner, they go to STV0299 for demodulation
process in tuner. (TU400) In this IC, QPSK (Quadrated Phase Shift Keying) demodulation and
Forward Error Correction (FEC) are done which is necessary to demodulate DVB-S
transmission. TS (transport stream): The multiplexed digital stream which includes video, audio
and data information related to more than one channel (can be only one channel for SCPC
signals) and DVB tables. TS signals which are generated after demodulation, reach to Sti5518
(IC100) via 8 bits data bus. However, Byte Clock (TSIn_BCLK), Packet Clock (TSIn _STROUT)
signals are also sent to ST5518 (IC100) for demultiplexing process of TS. STV0299 is controlled
2
by I C. In addition, 22kHz tone which is needed for DiSEqC signals, is generated at pin12 (Alps)
or pin10 (Sharp) of STV0299 in tuner.
LNB supply voltage (13/18V) is regulated via power board. Switching of supply voltage
between LOOP_IN and LNB_SUPPLY is done by Q402 transistors. The voltage on R403 is
proportional with the current of LNB supply. Overload on LNB supply increases the voltage on
R403, which results switching of Q400, Q401. By this way input LNB_OVERLOAD signal port of
Range of Voltage
+5V
+5V
Rev 1.0 21.10.02 16:23
Range of Voltage
-----
31V – 34V
11.8V – 12.20V
4.7 V – 5.3V
3.6 V – 3.9V
Range of Voltage
13 V – 14 V
17V – 19V
31 V – 34 V
11.8 V – 12.2 V
4.8 V – 5.2 V
3.3 V – 3.6V
2.4 V – 2.7V
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