Gigabyte B150M is powered on and powered off (CPU power supply chip, upper and lower tubes are damaged)

Gigabyte B150M is powered on and powered off (CPU power supply chip, upper and lower tubes are damaged).

When we measured the condition of the CPU power supply tube, we found that the 12V voltage from the main board was pulled down to 0.6V after passing through a resistor, which is definitely wrong. The specific maintenance process is as follows:

“Machine model” Gigabyte B150M

【 Fault Phenomenon 】 Power on and power off

[Maintenance process] I received a desktop motherboard sent by a customer for repair, the model of which is Gigabyte B150M. The fault is that I switched on the power and pressed the power-on key to turn on and turn off the power.

Measuring the power supply of the motherboard found that most of the power supply was available, but SLP-S3 was always turned off by IO, which led to the power failure of the whole machine. When measuring from the back to the front, it was found that the CPU power supply did not come out. This motherboard was powered by a three-phase CPU. When we measured the conditions of the CPU power supply tube, we found that the 12V voltage from one motherboard was pulled down to 0.6V after passing through a resistor, which was definitely wrong.

After removing the tube, the voltage returned to normal, indicating that the voltage was pulled down due to the damage of MOS tube. After replacing it with a new power supply chip, it was found that although 12V would not be pulled down, the CPU power supply still did not come out. We measured the opening of CPU power supply, power supply, SVID signal waveform and voltage.

Gigabyte B150M power-on and power-off Figure 1

Then we directly replace the CPU power supply chip, and after the chip is powered on, we find that the CPU power supply has come out, but only two ways.

Gigabyte B150M power-on and power-off Figure 2

This may be a problem with the circuit design. We connected the motherboard to the screen and started the test, and found that it can be started normally at this time.

Gigabyte B150M power-on and power-off Figure 3

[Maintenance result] There is no problem in the peripheral interface and card slot of the test motherboard, and the baking machine is normal, so the maintenance is over.