How to make 3.3v 1A dc supply from 4.5v, 5v, 6v or greater than these value.
LCD/LED tv no picture problem/white screen
Some days ago my LCD tv was not working properly, only the sound was ok and picture was not displaying. I checked and I was not getting any fault. I again 2 and 4 times checked the panel circuit which is connected with the display. I research more on google and YouTube and then I got knowledge about this problem of LED/LCD tv, and I know that when sound is ok and only graphics are not displayed in screen, the screen fill with solid white light and looks like a plain white are on full screen. No picture only sound – In this symptom, mostly problem is due to the power supply failure in the panel power supply.
Capacitor short – If any capacitor is shorted then also the supply voltage show 0v, Check the capacitors using continuity mode of multimeter and check if beep sound produce from both side of capacitors. If yes, simply replace that capacitor and check the voltage. In the case of all capacitors is ok very much possible to power supply stopped due to linear regulator ic or MOSFET etc damage.
Power supply problem on Panel board– Power supply stopped in any section on panel board by many reasons like any capacitor shorted, resistor shorted, burnt regulator ic, transistor or MOSFET failure etc. On this board there are many test points already placed in the form of copper pad. First need to find the ground trace on pcb board. By using multimeter hold on one probe of meter hold on the ground line, the second probe holds one by one each test point carefully, see if voltage show less than 1v (0.8v, 0.3, 0.5v) it means the supply of that point or that section stopped and any component not working properly which responsible to provide the supply. Find the damaged component and read the model name/number code on this and search on google, you will get the all information about that like what is that, what is working, what is the output voltage of this etc.
In my case there was a 4 pin ic (SMD) burnt named-ME 600D, this is a regulator ic which gives output 3.3v 1A regulated dc supply.
There was a problem to find this or similar ic to replace, at this time one other problem is to replace the SMD ic is not easy without the proper SMDs tools. There are many ICs that used to 3.3v regulated supply like AMS1117, LM3940 etc but in the local market, it is hard to find this ic. If I start to supply of 3.3v of 1A regulated, then the panel works properly and the problem of no graphic in tv display will be solved easily.
How to make 3.3v 1A regulated supply without ic AMS1117
Here I am discussing the way of how to start 3.3v supply using without regulator ic AMS1117. One most popular voltage regulator ic is LM317, this ic provides a minimum of 1.5 volt to a maximum 40v at the maximum current Load up to 1.5A. This is an adjustable voltage regulator which can able to provide 3.3v output at even 4.5v minimum input voltage. By connecting the proper resistor you can set the output voltage. This ic available is in the TO220 package that does not adjust at the place of SMDS. You should connect the wires from the board where the input and output are required with also a ground connection. Carefully solder the wires from the panel board with the LM317 ic and fix it with a non-conductive material anywhere near the board.
First, find the accurate resistor value for the required output voltage and the connect the resistors and connect first only input terminal with the panel and check the output terminal of LM317 ic if you find the output voltage at required (vary not more than 0.4v) then it will ok to use to provide supply to the panel board. I hope this will 100% work, I also use this technique for my LED tv and this still working fine.
You can use the LM317 resistor and voltage calculator to find the accurate output voltage and resistor value for this.
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