ASUS n551bios does not boot from USB disk

php editor Xinyi brings you the solution to the problem that the BIOS of the ASUS n551 laptop does not start with a USB disk. When using the ASUS n551 computer, we sometimes encounter the situation that it cannot be started through the USB disk, which brings certain troubles to our use. But, luckily, there are some simple steps we can take to fix this problem and get your computer booting up normally. Let’s take a look at the specific solutions below!

[Fault Phenomenon]: No display when booting, the fan spins wildly.

[Cause of failure]: The customer described that it was left at home for 3 months and was not used, and it would not be displayed when it was turned on again.

Computer model

[Repair process]:

I picked up a computer yesterday and quoted 800 yuan to repair the motherboard. I will disassemble it in the morning After turning it on, I found that the current on the bare board jumped, up to 1.6A, but there was no display, and the fan rotated very quickly. After measurement, it was found that the COM voltage and the voltage of each inductor on the mainboard were normal and there was no abnormality.

The next step is the same as everyone else... flash the BIOS.

Motherboard diagram

Fortunately, I have directly cleaned the dust of this model of machine and have a backup BIOS.

Compare the board number, the BIOS of the graphics card is exactly the same, flash it...The current jumps slowly, and it still does not display after waiting for a minute. The backup BIOS ME module is It's from other machines, so you have to wait a little longer.

Then I downloaded various BIOS from the Xunwei forum, including factory originals and peer backups. It doesn't work even if I swipe it back and forth. It is better to flash the BIOS of the machine itself. It seems that it is not a BIOS problem.

The next step is to work on the motherboard. First take out the memory value card. The reset voltage is 1.35V, VREF is 0.65V, VDD is 1.35V, VTT is 1.35V, the two data buses are only 2.9V, and VDDSPD is only 2.2V.

The two data buses are only 2.9V

VDDSPD is only 2.2V

This must be It's not normal,

still have to download some bitmaps.

Open the drawing and find the resistor for the SMB_DAT_S pull-up.

SMB_DAT_S pull-up resistor

Measure 3VS voltage

It seems that this is the voltage The problem is that VDDSPD is also pulled up by 3VS. The 3VS converted by the 3VS conversion tube PQ9101 is only 2.2V.

The 3V converted by PQ9103 is 3.3V.

I looked for this kind of 6-pin conversion tube on the material board, but couldn’t find it. Simply fly the wire directly from 3V to 3VS.

Flying line diagram

Connect the screen to the machine!

Lighting up picture

Now, the repair is over!

This case is provided by Xunwei.com student (Duan Linxi).

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