akira 21SHS3 Series, Руководство по обслуживанию

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Model No: 21SHS3-CE.doc
Version 1.0
GENERAL DESCRIPTION
THE SURVEY
Table 1, the main IC and functions
Number Function IC Remark
1 Power supply KA5Q0765RT N611
2 CPU + SIGNAL PROCESSER OM 8370 /TDA9370 N301
3 Field driver STV9302A N401
4 Sound driver AN7522N N161
5 AV SWITCH TC4052BP
N801 (Video)
N161 (sound)
6 Memory AT24C08 N702
7 Photo-coupler PC817B N504
8 IR-receiver HS0038A2 U701
9 8V regulator L7808CV N503
10 5V regulator L7805CV N505
SIGNAL PROCESS
The TV signal enters into tuner (A201) from cable or antenna. Pin 10 and pin 11 of N301 are combined
to select the band. Pin 4 of N301 outputs PWM tuning signal. The 38.9MHz IF signal is coupled to
V308 (pre-amplify) and then to SAWF (Z301). After processed in the SAWF, the 38.9MHz signal gets
to pin 23 and pin 24 of OM8370. The IF circuit in OM8370 includes such unit as the AGC amplifying
circuit, 38.9MHz oscillator, PLL video demodulator, video amplifier, IF identify circuit and AFT
circuit. The demodulated signal (CVBS) comes from the pin 38 of OM8370, the sound signal comes
from the pin 44.
The internal CVBS signal needs norm identification then outputs from pin 38 of OM8370, via the trap
circuit (composed of the V351, Z351, Z354, V352 and so on) feeds back to the pin 40 of OM8370. The
RGB signal comes from pin51, Pin52, Pin53 of OM8370, and outputs to the CRT board. The internal
sound signal comes from pin 44 of OM8370 and then input to pin 1 and pin 12 of HEF4052BP. The
sound signals from RF and AV are selected in it. The selected signal is output from Pin 3 and pin13,
then input AN7522N (sound amplifier) or output from AV terminals.