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THOMSON MT31AS, Service Manual

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THOMSON MT31AS Service Manual Download Page 13

                                                                                Service manual of MT31AS 

 

The waveform of MOS

’

S 

 

The Schematic diagram of BL driver 

5.3. Decode and I/O Units 

5.3.1. The flow of low voltage power supply 

Checking  the  low  voltage  power  supply  is  principal step  when  you  are  maintaining  the 

badness.  It

’

s  meaningless  to  analyzing  the  circuits  without  affirming  the  power  supply  is  OK. 

Referring the flow of low voltage power supply, the Decode and I/O units get +12V power from 

the power unit. Each voltage of the elements need is transformed from +12V by DC-DC and LDO. 

Switch IC and MOS switch circuits can control the supply current in real time to insure the Main 

board work normal. 

Summary of Contents for MT31AS

Page 1: ...1 THOMSON Service Manual For MT31AS Product Support Office 2014 6 11 Model T28ED12DU 01B T32ED13DU 01B T24E12DHU 01B T24 E12DHU 01W ...

Page 2: ...diagram of Main board 7 5 The Test Guides Of Main Board 7 5 1 Power Unit 9 5 2 Back light driver units 10 5 3 Decode and I O Units 11 5 3 1 The flow of low voltage power supply 11 5 3 2 Small signal process 14 5 3 3 Control BUS 15 5 4 Module Circuits Test 16 5 4 1 The audio power amplifier 16 6 Troubleshooting Flow Chart 17 6 1 Green Power LED does not turn on 17 6 2 Abnormal display 18 Attachment...

Page 3: ...2DHU 01W The test of Main board includes three parts Power unit flow of signals and specific circuits explanation It will be easy to solve the problem when you analyze from power signals and specific elements The part of common fault maintains is a summarization from our company s daily product It is in the end of this manual It may be helpful to the readers ...

Page 4: ...articularly at plugs receptacles and the point where it exits from the component 7 Do not use this component near water 8 Only use the attachments accessories specified by the manufacturer 9 Clean only with dry cloth 10 Use only with the cart stand tripod bracket or table specified by the manufacturer or sold with the component When the TV is placed on a cart use caution when moving the cart to av...

Page 5: ... charges 15 An outside antenna system should not be located in the vicinity of overhead power lines or other electrical light or power circuits or where it can fall into such power lines or circuits When installing an outside antenna system extreme care should be taken to keep from touching such power lines or circuits as contact with them might be fatal 16 Wall or Ceiling Mounting The product sho...

Page 6: ...Interface Built In Max Storage Channels 256CH PC RGB Format Up to 1920 1080 60Hz CVBS Video System PAL NTSC SECAM Video level 1 0 VP P 5 Component 480i 480p 576i 576p 720p 1080i 1080p HDMI 480i 480p 576i 576p 720p 1080i 1080p Support MHL AUDIO INPUT PC Audio Earphone Input 0 2 2 0 VRMS CVBS Audio Component Audio VIDEO OUTPUT CVBS Video System PAL NTSC SECAM Video level 1 0 VP P 5 AUDIO OUTPUT CVBS...

Page 7: ...H 264 mkv mov MPEG 4 H 264 mpg MPEG 1 2 4 rm rmvb RV8 RV9 RV10 COOK Max Resolution And Frame Rate 1280 720 30fps Max Data Rate 10 Mbps Music mp3 MP3 Sample Rate 32K 48KHz Bit Rate 32K 320Kbps Channel Mono Stereo wma WMA Sample Rate 8K 48KHz Bit Rate 128K 320Kbps Channel Mono Stereo aac AAC Sample Rate 8K 48KHz Bit Rate 128K 442Kbps Channel Mono Stereo Photo jpg jpeg Progressive JPEG Max solution 1...

Page 8: ...Service manual of MT31AS Back view Inner view ...

Page 9: ...ual of MT31AS 3 The Exploded view of 28M1300 Please refer to the attachment 1 4 The Schematic diagram of Main board Please refer to the attachment 2 5 The Test Guides of Main Board The physic picture of main board ...

Page 10: ...divided into three parts Power BL driver Decode and input output Power includes EMC Wave filtering full wave rectifier and DC DC power unit The BL driver use constant current source realized by the DC DC to illumine the light It can supply constant ...

Page 11: ...from Main board to power grid The resistance of NTC inspects the abnormal temperature and can fuse the fuse to protect circuits Full wave rectifier translates AC into DC HV receive DC 300V The DC DC unit adopts Fly back structure MOS control the on off by the power manage IC Transformer open and close intermittently The main grade coupling voltage will be commutated to VCC 18V supplying for the po...

Page 12: ...ence And it promotes VLED outputting by Power to LED so as to illume the LED Specific PWM signal is generated by BL driver IC The IC is controlled by BL_ON and DIM The voltage will be promoted when BL_ON is in high voltage level LED feedback is adjusted by DIM duty ratio lineally so the brightness is adjustable 12V_POWER is the supply for IC The driver ability is set by the periphery such as ISET ...

Page 13: ... you are maintaining the badness It s meaningless to analyzing the circuits without affirming the power supply is OK Referring the flow of low voltage power supply the Decode and I O units get 12V power from the power unit Each voltage of the elements need is transformed from 12V by DC DC and LDO Switch IC and MOS switch circuits can control the supply current in real time to insure the Main board...

Page 14: ...ply of Main board when power is on Test the DS1 s cathode voltage to GND is 12V for debarring the power unit abnormal 5V_STB and 3 3V_STB are get from 12V by U3 and UA3 The power supply on standby just provides to Main IC Key board IR board and the power on signal of Main IC start ...

Page 15: ...and U5 to break off after power on Supply power for DDR FLASH and TUNER 2 LVDS_PWR_EN Power supply for panel enables Control F04 to supply power for OPEN CELL singly 3 BL_EN BL on off Enable Control BL driver IC to supply the rise voltage impulse 4 MUTE Mute function control UA1 s work state When POWER_ON is in effect the input of 5V_NOR can be tested from UA01 and UA02 The 5V_NOR1 can be tested f...

Page 16: ...lated to parallel digital signals entering main IC by DVB T2 T C decode chip Analog part signal is inputted to main IC FLASH storage program and user data Main IC read the FLASH s program when it is work The key data generated by users execute operation is also deposited into FLASH Picture signals are outputted to OPEN CELL by LVDS It can generate LVDS or transformed to mini LVDS by T con in order...

Page 17: ...AGC to control the intension of TUNER s output signals and uses I2C bus to achieve options such as channel selection and setting VGA port includes I2C bus It is used to UART debug and transcribe factory data expect EDID communication FLASH communicates with main IC by SPI BUS Main IC needs to communicate with FLASH frequently in power on IR board receives infrared signal then Main IC identifies th...

Page 18: ...of AMP IC s peripheries include Gain Control Power restrict Mute control and Abnormal feedback Mute control is realized by software and hardware control Software mute maps to Main IC s I O port Hardware mute is work in AC cut off AMP s PIN SD will be pulled to low level to mute when power is cut off for 60ms C127 will be charged when power is on And it will discharge though Q101 s E Because B is p...

Page 19: ... of AMP IC s peripheries The Schematic diagram of hardware mute 6 Troubleshooting Flow Chart These flow charts may not match every single defeat TV set but they can give you useful advices when you meet the same defeats described on the titles below 6 1 Green Power LED does not turn on The TV is not work ...

Page 20: ... will be useful to analyzing the problems quickly recur to the serial interface tools 6 2 Abnormal display Check each DC DC and there terminal voltage regulator unit DDR Abnormal Ok Both have Check each DC DC unit s outputs and the power supply of Main IC and DDR Check P_ON DIM BL_ON Not work Check 3 3VSTB and 12V 24V Both no Check Power Unit Only has 3 3VSTB Check Reset signal of Main IC Check II...

Page 21: ... like this Put the good machine s TV AV signal into the bad machine s Main IC and put the bad machine s TV AV signal into the good machine s Main IC If the problem follows the action the problem is caused by fore end circuits If the problem not follows the action the problem is caused by the Main IC or the periphery circuits 6 3 Abnormal sound Check the Main IC periphery circuits Try to upgrade so...

Page 22: ...e sources defeat Check AMP s outputs Ok No Check the Main IC periphery circuits Try to upgrade software Change main IC DDR Check the power supply for AMP Check the Mute Check the Reset signals of AMP Check the abnormal source s audio signal has been inputted into Main IC correctly Check the HDMI EDID and HDCPKEY Check the signals from Main IC to AMP Check IIS and IIC bus Check the filter capacitan...

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