Saturday, December 12, 2015

Sharp LC-22LE250 - LC-24LE250 How to enter to service mode and troubleshooting

Contents of this article 

  • How to enter to Service mode 
  • Troubleshooting 

Sharp LC-22LE250 - LC-24LE250

No Backlight Problem
Problem: If TV is working, led is normal and there is no picture and backlight on the panel.
Possible causes: Backlight pin, dimming pin, backlight supply, stby on/off pin BACKLIGHT_ON/OFF pin should be high when the backlight is ON. R119 must be low when the backlight is OFF. If it is a problem, please check Q10 and the panel cables. Also it can be tested in TP50 in main board.
Dimming pin should be high or square wave in open position. If it is low, please check S60 for Mstar side and panel or power cables, connectors.
Backlight power supply should be in panel specs. Please check Q33, shown below; also it can be checked TP53.
STBY_ON/OFF_NOT should be low for tv on condition, please check Q11’s collector.
CI Module Problem
CI is not working when CI module inserted.
Possible couses:
Supply, suply control pin, detect pins, mechanical positions of pins.
# CI supply should be 5V when CI module inserted. If it is not 5V please check CI_PWR_CTRL, this pin should be low.
# Please check mechanical position of CI module. Is it inserted properly or not?
# Detect ports should be low. If it is not low please check CI connector pins, CI module pins.
Staying in Stand-by Mode Problem:
Staying in stand-by mode,no other operation. This problem indicates a short on Vcc voltages. Protect pin should be logic high while normal operation. When there is a short circuit protect pin will be logic low. If you detect logic low on protect pin, unplug the TV set and control voltage points with a multimeter to find the shorted voltage to ground.
IR Problem
Problem: LED or IR not working.
Check LED card supply on MB95 chasis.
Keypad Touchpad Problems
Problem: Keypad or Touchpad is not working.
Check keypad supply on MB95.
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.
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.
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.
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.
Service Menu Settings
In order to reach service menu, first Press “MENU” buton, then write “4725” by using remote controller.
You can see the service menu main screen. You can check SW releases by using this menu. In addition, you can make changes on video, audio etc. by using video settings, audio settings titles.