NEC DTE-29U1TH, Руководство по обслуживанию

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Service Manual CP-785F
High impedance
This mode can be used for input only operation of the port.
Special port for LED
Pin 10 and 11 have the same functionality as the general I/O pins but in addition, their current
source and sink capacity is 8 mA instead of 4 mA. These pins are used for driving LED s via a
series current limiting resistor.
-Controller I/O pin configuration and function table
pin name configuration description
Stand by TV ON
1 n.u. High impedance High impedance not used
2 SCL Open Drain Open Drain Serial clock line
3 SDA Open Drain Open Drain Serial data line
4 A/V SW High Impedance See Table Above External Video Switch
5 OCP High impedance High impedance Over Current Protection
( Switch the set OFF if
the voltage on this pin is
<2.33V )
6 - High impedance High impedance For factory use only
7 Key in High impedance High impedance Local keyboard input
8 A/V SW High impedance See table above external video switch
10 Red LED High impedance Open Drain
11 Green LED Open Drain High impedance
62 Audio mute Push Pull Push Pull High in stand by mode
5-5 Sound processing
Analogue sound IF - input section
The input pins and ANA_IN- offer the possibility to connect sound IF sources to the
MSP 3415D. The analogue-to-digital conversion of the preselected sound IF signal is done by
an A/D converter, whose output is used to control an analogue automatic gain circuit (AGC),
providing an optimal level for a wide range of input levels.
Quadrature Mixers
The digital input coming from the integrated A/D converter may contain audio information at a
frequency range of theoretically 0 to 9 MHz corresponding to the selected standards. By means
of two programmable quadrature mixers, two different audio sources ; for example, NICAM and
FM-mono, may be shifted into baseband position.
Phase and AM discrimination
The filtered sound IF signals are demodulated by means of the phase and amplitude
discriminator block. On the output, the phase and amplitude is available for further processing.
AM signals are derived from the amplitude information, whereas the phase information serves
for FM and NICAM demodulation.