uh now I finally know why some old phones won't work while charging with one specific charger

This depends, I belive this is commonly done to enable connecting PSUs in series.

yes. Here's a cheap psu, it's very simple :D

I have done it successfully and plenty of verity of adapters such.

Thanks

I see there is 1 15V zener diode there, so the voltage is always a steady 15V. I removed the capacitor because the grid in my country only has 2 wires. There is no ground wire. If not remove the capacitor, when touching the output. I will receive a slight electric shock

​@@PhdHung Ah ok. Then this was only a sample schematic and this is a supply with PE on secondary -. The 2.2nF capacitor in the schematic were normally ok for touch current requirements for class II supplys. There can be some other issues if output voltage is higher then designed but this supply has apparently enought reserve for that range for normal input voltage.

thanks bro

I thought he'll modify PWM ;) signal and not a potentiometer at the output :D, an odd way to do it IMHO ;).

no need to reduce amper

CANT 15V TO 24V (DO THIS SOME TIME BLOWING THE POWER MOSFET, YOU HAVE TO FIND 19.5V ADAPTOR

What's happening there is you are trying to over switch the ic. The so called modification here is actually increasing the duty cycle of the switching ic. You can't go beyond a specific T on.

Thanks bro

What ever be the SMPS or adaptor find TL431 has 3 pin leads, Leave the Grounded pin and one more pin connected directly to Opto coupler also leave that and the remaining pin connected to dual resistors 1st resistor (R9 in this video) one end connected with the remaining pin of TL431 and other end with ground. another VR and resistor in serious are coupled as a single resistor with o/p voltage pin. So find out easily by using multi meter at continuity checking mode and check remaining pin of TL431 and connecting resistor other end is with +o/p and another similar resistor with ground . thus these 2 resistors need to change 1 by fixed one and another by pot. thats all. After his video I have done several adapters.

thanks bro

Of course

@@PhdHung no, probably not! You have to change the output diode and use a diode that can handle a higher peak!

I know I'm late, but maybe you still didn't find out and wonder. It's not a diode, it's the TL431, need to understand the circuit a little bit to find it by logic, it drives an opto-coupler and should be marked as "U" on the pcb, it could also be in a to92 housing or the psu work another way.

Thay con điện trở phân áp nối xuống mass thành biến trở là ok. Cái này dễ mà, bạn coi lại video có sơ đồ nguyên lý đấy.

Yes, it caused electric shock, so I removed it.

@@PhdHung cool, then it was simply defective, then it is better replaced, since its purpose is to close the high frequency loop, where the other halve of the problem (signal noise generator) is the capacity from primary to secondary side in the transformator, this cap close this, and avoid huge radiation between prim-sec side

thanks. I know that.

Remove resistors connected to gnd. Find it near tl431

@@PhdHung All i do it is done, but if the voltage below 18V beats a sound, the more clearly audible if the voltage is lower, the led blinking, the voltage unstable, how to fix it ?

Did you removed the cap ?

I mean miler cap

ok

@@PhdHungthanks

cái này dễ mod lắm anh

@@PhdHung anh mở 1 cục sạc asus thấy không giống cái của em....nhưng từ từ anh mò .....chắc cũng ra ...he he he ...cám ơn em đã đăng

The overall adapter power remains the same. If voltage increases, the current decreases and vice versa, however the max current is still the limit of the secondary winding of the transformer.

I removed the feedback voltage resistor and replaced it with potentiometer

Which and which are the value of former feedback resistor

5k

Basically yes, aslong it uses the TL431, but need to understand the circuit to find it, also for safety, don't do something like that with electric stuff if you don't understand it, high or low voltage doesn't matter, it still can be very dangerous.

resistor 4k7 for LED :D

Why only one cap? Two small provide better filtering and is often easier to fit. But 50v rating provides some extra headroom and is smart considering the operating conditions in these non-ventilated units. 100v is just a waste of money and would not fit inside the case. You cant substitute voltage rating for capacitance. If your goal is improved filtering you could relocate the last cap to the unused V-2 and V+2 points, cut the positive trace right after the original location of 2nd cap and bridge with an inductor. This would be a huge improvement as far as noise go. If you want, you can think of it like only one capacitor... just with an added L2 filter. That being said, dirt cheap capacitors have no place in these things. Two high quality 50v 470uf with 105c rating is about $1. If you are going to use these things as a variable PSU for projects and testing, filtering is important and even crucial when dealing with ICs and microcontrollers.

Very difficult, you need rewinding the transformer.

67,2 ? for what?

dell computer charger has 3 wires. +, - and PG. You can remove PG wire

@@PhdHung i got an HP one and it also has 3 wires (i don't want to kill it anyway i need it for the computer because the third wire tells the laptop it's not connected to any random power supply and if there is none it doesn't work so i can't use any charger! #SAD )

@@PhdHung

Me too

If the resistance is large, the voltage increases

@@PhdHung depends on which feedback resistor you change as there are at least two of them in a divider bridge!

Marlon Diego in that case you remove the overvoltage protection if it has some integrated chip for the working proces just diseable the pin for that and its done an if it isnt with a chip just short the two legs on the optocoupler on the primary side

The third wire tells the laptop what charger is connected (90w 100w 120w etc) and that its a genuine charger or not

It doesn't matter, use the two wires you get 19V in between of!

here 320volt.com/en/battery-charger-with-flyback-smps-mod/

anh thay con biến trở vô, vặn đến 24V thì rút điện, đo xem bao nhiêu ôm rồi thay bằng con trở cứng vô. nên dùng tụ 35V hoặc 50V cho an toàn anh

@@PhdHung ok ,cám ơn em, cách này hay với anh.cám ơn nhiều,he he eh