Skyworth 8M19 Chassis LED TV with TV Screen Full of Vertical Lines/Bars Problem
This TV problem solved without any cost, yes $0! Today come in a Skyworth 32 inches 8M19 Chassis LED TV with the TV screen full of vertical lines/bars problem. The customer said the former TV repairer told him his TV is the screen was broken and no worth to repair.
After power on the TV, the TV has sound, but the screen shows as photo above, yes, it is looks like screen problem and it’s full of vertical lines. But these lines position are not steady, sometime is will change to another position. Use the remote control try to call out the TV OSD Menu and the TV screen is shows as photo below:
If the TV display problem but their OSD Menu is normal, that’s mean it is NOT the screen/panel broken problem (please refer to my eBooks series has mention it before)! After called out the OSD Menu successfully, try to play their features through the remote control. When try to AUTO Search the TV Channel, the channel frequency is not running just fixed on that frequency values only, even try change to manually search channel also not function. Please refer to the photo below:
From the above TV checking steps, suspect the TV problem is in the Mainboard! If you’ve the special tools like LVDS Tester, TV Mainboard output Tester or etc, you also can check the TV mainboard output to make sure it is the TV Mainboard problem or not. So start to check the TV mainboard LDO voltage output, crystals & etc (for more detail please refer to V6.0 ebook). Found their TV Mainboard core voltage was abnormal. When check the Main Chip/CPU core voltage, it’s shows the voltage values is: 1.88V but not stable. Sometime this voltage will increase to 2.21V! It is confirmed that the problem is TV Mainboard core voltage abnormal, and the normal core voltage values is about 1.2V (it will depend on the types of TV Mainboard).
Refer to the TV Mainboard schematic diagram, this TV Mainboard core voltage circuit is as photo below:
First check the Core Voltage input voltage, 5Vstb supply, and it is normal. Refer to the TV mainboard schematic diagram, suspect the core voltage problem is cause by the U8 (NCP1595A) or their FB feedback circuit corresponding components abnormal. So first checking their R24, R28 & R86. But these resistors are nearby the L111 coil/inductor and cover with the white glue. Normally, TV Mainboard manufacturer will put this white glue on the coil to prevent the coil vibrate. If need to check these resistors, must remove the white glue first. After removed the white glue, check the R24, R28 & R86 resistors and all these resistors values is normal. Suddenly, thought that this kind of white glue may cause the leakage in between the electronic components contact pin/s after long time use! Power on the TV Mainboard and try to check their core voltage output, bingo! It is back to normal 1.24V now! Please refer to the photo below:
This Skyworth LED TV is working properly now without change any spare part or electronic component! (Yes, the solder and soldering Iron & electricity fees are not included :-))
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