Sharp LC-50LE761K Service Manual ▷ View online
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F. USB Problems
Problem: USB is not working or no USB Detection.
Check USB Supply, It should be nearly 5V. Also USB Enable should be logic high.
G. No Sound Problem
Problem: No audio at main TV speaker outputs.
Check supply voltages of 24V VDD_AUDIO, 3.3V AUDIO_AVDD and AUDIO_DVDD
with a voltage-meter. There may be a problem in headphone connector or headphone detect
circuit (when headphone is connected, speakers are automatically muted). Measure voltage at
HP_DETECT pin, it should be 3.3v.
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E. Keypad Touchpad Problems
Problem: Keypad or Touchpad is not working
Check keypad supply on MB90.
5. Keypad Touchpad Problems
6. USB Problems
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F. USB Problems
Problem: USB is not working or no USB Detection.
Check USB Supply, It should be nearly 5V. Also USB Enable should be logic high.
G. No Sound Problem
Problem: No audio at main TV speaker outputs.
Check supply voltages of 24V VDD_AUDIO, 3.3V AUDIO_AVDD and AUDIO_DVDD
with a voltage-meter. There may be a problem in headphone connector or headphone detect
circuit (when headphone is connected, speakers are automatically muted). Measure voltage at
HP_DETECT pin, it should be 3.3v.
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H. Standby On/Off Problem
Problem: Device can not boot, TV hangs in standby mode.
There may be a problem about power supply. Check main supplies with a voltage-meter. Also
there may be a problem about SW. Try to update TV with latest SW. Additionally it is good
to check SW printouts via Teraterm. These printouts may give a clue about the problem. You
can use Scart-1 for terraterm connection.
I. No Signal Problem
Problem: No signal in TV mode.
Check tuner supply voltage; 5V_VCC, 3V3_TUNER and 1V8_TUNER. Check tuner options
are correctly set in Service menu. Check AGC voltage at IF_AGC pin of tuner.
7. No Sound problem
8. Standby On/Off Problem
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H. Standby On/Off Problem
Problem: Device can not boot, TV hangs in standby mode.
There may be a problem about power supply. Check main supplies with a voltage-meter. Also
there may be a problem about SW. Try to update TV with latest SW. Additionally it is good
to check SW printouts via Teraterm. These printouts may give a clue about the problem. You
can use Scart-1 for terraterm connection.
I. No Signal Problem
Problem: No signal in TV mode.
Check tuner supply voltage; 5V_VCC, 3V3_TUNER and 1V8_TUNER. Check tuner options
are correctly set in Service menu. Check AGC voltage at IF_AGC pin of tuner.
9. No Signal Problem
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CHAPTER 7.MAJOR IC INFORMATIONS
[1] INTRODUCTION
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1. INTRODUCTION
17MB90-2 main board is driven by MStar SOC. This IC is a single chip iDTV solution
that supports channel decoding, MPEG decoding, and media-center functionality enabled by a
high performance AV CODEC and CPU.
Key features includes,
Combo Front-End Demodulator
A multi standart A/V format decoder
The MACEpro video processor
Home theatre sound processor
Internet and Variety of Connectivity Support
Dual-stream decoder for 3D contents
Mılti-purpose CPU for OS and multimedia
Peripheral and power management
Supported peripherals are:
1 RF input VHF I, VHF III, UHF
1 Satellite input
1 Side AV (CVBS, R/L_Audio)
2 SCART socket(Common)
1 YPbPr (Common)
1 Side S-Video(Common)
1 PC input(Common)
4 HDMI input(Common)
1 Common interface(Common)
1 Optic S/PDIF output(Common)
1 Stereo audio input for PC(Common)
1 Subwoofer output(Common)
1 Headphone(Common)
2 USB(Common) and 2 Optional for Air mause and Wi-Fi dongle
1 Ethernet-RJ45 (Common)
1 External Touchpad(Common)
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