14.7.No Sound Problem ....................................................................................................... 53
14.8.No Sound Problem at Headphone ................................................................................ 53
14.9.Standby On/Off Problem .............................................................................................. 53
14.10.No Signal Problem ................................................................................................... 54
1. INTRODUCTION
17MB8 mainboard is driven by MediaTek MT5356. This IC is capable of handling Video
and audio processing, Scaling-Display processing, 3D comb filter, OSD and text
processing, LVDS/mini-LVDS transmitting, channel and MPEG2/4 decoding, integrated
DVB-T/C demodulator and media center functionality.
TV supports PAL, SECAM, NTSC colour standards and multiple transmission standards
as B/G, D/K, I/I, and L/L including German and NICAM stereo. Also DVB T, DVB-C are
supported internal demoulators of MediaTek IC and DVB-S/S2 is supported with externall
demodulator.
Sound system output is supplying max. 2x8W ( less 10%THD at max output) for stereo
speakers.
8
Supported peripherals are:
1 RF input VHF I, VHF III, UHF @ 75Ohm(Common)
1 Side AV (CVBS, R/L_Audio)
1 SCART socket(Common)
1 YPbPr (Optional)
1 PC input(Common)
2 HDMI 1.3 input(1 HDMI input is common, 1 input is optional)
1 S/PDIF output(Optional)
1 Headphone(Optional)
1 Common interface(Common)
1 USB input is
1 On-board Keypad(Optional)
1 External Keypad(Optional)
1 External TouchPad(Optional)
ommon)
1.1. General Block Diagram
1. TUNER(S 2156)
The Si2156 integrates a complete hybrid TV tuner supporting all worldwide
terrestrial and cable TV standards. Lever
generation digital low-IF architecture, the Si2156 maintains the unmatched
performance and design simplicity of the original Si2153 while further reducing
footprint size. No external LNAs, tracking filters, or SAW filters are used. Compared
with competing silicon tuners and discrete MOPLL-based tuners, the Si2156
delivers superior picture quality and a higher number of received stations in realworld conditions due to its very high linearity and low noise. Interfacing the Si2156
seamlessly with the Si2165 DVB-T/C demodulator creates a DVB-T/C receiver plus
PAL/SECAM tuner. The Si2156 is pin-compatible with the Si2176 hybrid TV tuner
with analog demodulator, providing customers unparalleled design flexibility.
Features :
aging Silicon Labs field proven third
BLOCK DIADRAM
M88TS2022 (Optional)
M88DS3002 (Optional)
2. AUDIO AMPLIFIER STAGE
STA381BWS
2.1. General Description
The STA381BWS is an integrated solution embedding digital audio processing, digital amplification,
FFXTM power output stage, headphone and 2 Vrms line outputs. It is part of the Sound Terminal®
family and provides full digital audio streaming from the source to the speaker, offering cost
effectiveness, low power dissipation and sound enrichment.
The STA381BWS input section consists of a flexible digital input serial audio interface, feeding the
digital processing unit, and an analog 1 Vrms input for a seamless connection with pure analog
sources. The serial audio data input interface supports many formats, including the popular IIS
format.
The STA381BWS is based on an FFXTM (Fully Flexible Amplification) processor, an
STMicroelectronics proprietary technology. FFXTM is the evolution of the ST ternary technology: the
advanced processor is available for ternary, binary, binary differential and phase shift PWM
modulation. STA381BWS embeds the ternary, binary and binary differential implementations, a
subset of the full capability of the FFXTM processor.
The STA381BWS power section consists of four independent half-bridges. These can be configured
via digital control to operate in different modes. A 2.1 channel setup can be implemented with two
half-bridges (L/R) together with a single full-bridge (subwoofer).
Alternatively, the 2.0 channel setup can be done with two full-bridges. When using this configuration
an external amplifier, for the SW channel, can be also driven through the PWM output. The
STA381BWS is able to deliver 2 x 20 W (ternary) into an 8 W load at 18 V or 2 x 9 W (binary) into a 4
W load plus 1 x 20 W (ternary) into an 8 W load at 18 V. The STA381BWS also provides a capless
headphone out (with embedded negative charge pump), able to deliver up to 40 mW into a 32 W
load or, alternatively, can be configured as a 2 Vrms line output.
The STA381BWS digital processing unit includes up to 12 programmable biquads (EQs) allowing
perfect sound equalization and offering advanced noise-shaping techniques.
Moreover, the coefficient range ensures a great variety of filter shapes (low/high-pass, low/high shelf,
peak, notch, band-pass). The equalization engine is fully compatible with the ST speaker
compensation technology embedded into the APWorkbench suite. A state-ofthe- art multi-band DRC,
STCompressorTM, equalizes the system to provide active speaker protection with full audio quality
preservation against sudden sound peaks. Moreover, STSpeakerSafeTM technology offers reliable
speaker protection under any condition. The master clock can be from stable BICKI (64xfs, 50% duty
cycle) or external XTI.
2.2. Features
Features
Wide-range supply voltage
4.5 V to 25.5 V (operating range)
27 V (absolute maximum rating)
I2C control with selectable device address
Full IC protection embedding:
Manufacturing short-circuit protection (out
vs. gnd, out vs. vcc, out vs. out)
Pre and post processing DC blocking filters
Checksum engine for filter coefficients
PWM fault self-diagnosis
STCompressorTM dual-band DRC
2.3. Absolute Ratings
2.3.1. Electrical Characteristics
2.3.2. Operating Specifications
2.4. Pinning
TS4962M (Optional 2,5W)
3. POWER STAGE
The DC voltages required at various parts of the chassis and panel are provided by a main power
supply unit. MB8
PW26, PW82-3, PW03, PW04, PW06, PW07 as main power supply and also with 12V adaptor.
Which power board can be used for board to board or cable connection?
chassis can operate with PW05, IPS60, IPS70, IPS16, IPS17, IPS19, PW25,
Board to board (BTB) :
Power Cable : PW25, PW26, PW82-3, PW03, PW04, PW06, PW07
The power supplies generate 24V, 12V, 5V, 3,3V and 12V, 5V,3.3V stand by mode DC voltages.
Power stage which is on-chassis generates 5V, 3V3 stand by voltage and 12V, 8V, 5V, 3V3, 2.5V,
1,8V and 1,2V supplies for other different parts of the chassis. Chassis block diagram is indicated
below.
The blocks on power block diagram is using dependent to main supply. For PW26 and PW27 just
common blocks are enough for proper operation.
Short CCT Protection Circuit
Short circuit protection is necessary for protecting chassis and main IC against damages when any
Vcc supply shorts to ground. Protect pin should be logic high while normal operation. When there is a
short circuit protect pin shold be logic low. After any short detection, SW forces LEDs on LED card to
blink.
PW05, IPS60, IPS70, IPS16, IPS17, IPS19
3.1. Power Management
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