Acer Laptops V Series 3-772g
Problem: Not turning on when plugged in
Possible Solution(s): check if there is 19 volt after the 2nd Mosfet, see picture for where to place red probe of your Multimeter
If there is 19 volt then your first 2 mosfets have not failed and the fault lies in deeper in the motherboard, if you dont see 19 v then:
- If you see fluctuating voltage like 17v then 20 then 15 then 19 and so on, if the voltage is fluctuating for more than 1 volt, then your power brick may be the culprit, if yes then check the power bricks output port with your multimeter, middle pin is 19v and the outer metal part is ground.
- if you see no voltage then either one of the mosfets may be blocking it, so check the input of the first mosfet, its marked yellow in the picture.
- if you have no voltage at the first mosfets input, then check if your multimeter is set up correctly by measuring a battery, if the multimeter is a known working one then check the power jack with your multimeter set to continuity, the middle pin is 19v so it is connected to the input of the first mosfet (yellow), and the ground is connected to the copper circle, if you dont hear a beep when connecting middle pin to input of the first mosfet, then check jack or cable if its ripped or broken somewhere, the same thing needs to be done to ground, outer shell of the power jack is ground, so check that with the copper circle if you hear a beep that means that its good, if not then the connection is broken. Important note 19v and ground must be seperate, you should never hear a beep longer than 1 second between ground and 19v.
- After checking the top stuff and you still dont see 19 v, even though your power brick has 19 v when you check it seperatly, then you have a short to ground after the 2nd mosfet which turns on the security system in your power brick cutting your voltage untill you unplug and plug it back in from your wall socket. At this point the problem can be anywhere.
Problem: A short after the 2nd Mosfet
Possible Solution(s): This is not the safest method but the one I use. It can destroy your PCH, CPU, RAM or GPU depending on where the short is.
- You will need a variable power supply, set it to 19v and put a limit of 1 amp, then place it where the red line is (output of the 2nd Mosfet) The Powersupply voltage will drop 3v,5v,10v, depending on how resistive the short is, lower resistance = less voltage drop, higher resistance means a higher voltage drop because our current is limited to 1 amp. if you see on your power supply 5v at 1amp that means that whichever component is taking that power its taking 5 watts of power which makes a lot of heat depending on the size of that component. use your finger to check which components are getting hot, if you cant find it then up your amperage limit to 2 amps, that will increase the heat output. After you found the fault remove the component and check again if the short is gone and replace the component, if the short still exists after replacing it then search further, the hottest component is the one thats shorted.
Problem: Not turning on but led lights are working
Possible Solution(s): If your lights are blinking that means we have power, and our 3.3v is working but something else is not working that is vital for your computer to turn on.
- Reset the bios: The bios is the software that your computer uses to know what it needs to do to get into Windows, if it got corrupted (which happens suprisingly often) then the Laptop wont know how it can load into Windows. A bios reset happens when your computers bios battery and main battery are unplugged. On the picture the gray line indicates where the bios battery is located. unplug the battery and wait for 1 minute. after that try turning it on. If it doesnt turn on check further solutions
- Faulty memory can cause your laptop to behave this way, if possible check the laptop with known working memory.
- The power button may be broken, if that is the case check with your multimeter on pin 3 from the right side (marked in blue in the 3rd picture). if you see 3.3v and it drops to 0 when you press it and goes back to 3.3v when you let go of the button then the power button is working. if it isnt working then short that pin to ground. if the laptop still doesnt work after shorting that pin t ground then see next.
- The problem may be your bios, and it is so badly corrupted that a reset doesnt help, at that point you will need to reprogramm it yourself. You will need to find a bios.bin from the internet. Google Acer aspire v3-772g bios.bin and you should be able to find it. To Programm the bios you must first find it, it is a chip that looks like in picture 4. this particular chip has markings Winbond 25q32VS. Winbond is the company name, 25 probably means the physical size, q32 is how big a capacity it has in magabits. Depending on the computer it may have 2 bios chips, in this case we also have 2. You will need a programmer like the EZP2019+ or CH341a, and the drivers + software. Please use a youtube video to get the software and driver part of this guide. After you have everything ready we can start the programming.take out the bios chip with a hot air station, place/ the chip in one of these interfaces (picture 5). then try and find your bios chip in the software. I am using NeoProgrammer and a Ch341a. In Neoprogrammer you can use the detect function Picture 6 shows a succesful attempt, if it doesnt work try reseating it all pins must make good contact and be in the right orientation. After neoprogrammer detected your bios it will ask you which type it is, this determines which feature sets your bios has, this can be looked up by checking the manual of the bios chip on the internet. if the names match then just pick that one, if they dont try to find it and match with a similar bios chip. You are almoust ready to programm, first read the bios and then save it to make a backup. (the green arroved chip image right from the floppy drive is the read function, floppy drive is the save function). After you have your bios backed up, then you have to first delete or clear the bios chip and then write to it, bios chips cant be overwritten only deleted and then written (at least older ones). the delete function is one with the red X and the write function is one with the blue arrow. You can use higher capacity bios chips like W25Q128 in a W25Q64 or any other smaller size, but you have to instead of detect use the search function to find the lower valued bios chip.
