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Gigabyte B460M POWER motherboard does not start, and a capacitor is removed for perfect repair.
A colleague sent a Gigabyte B460M POWER motherboard for repair, and the fault phenomenon was that the short switch pin did not trigger.
Power-on measurement shows that the standby voltage is 5V, and the voltage of 3.3V is normal. The 1.05V voltage of the bridge is 0V, which is abnormal.
checkcircuit diagramAs follows: pin 7 is the main power supply of the chip, pin 3 is on, and the voltage of pin 7 is 5V measured by multimeter. The ON signal of pin 3 EN is 0V, which is abnormal.
Trace the source of the 3-pin turn-on signal, as shown in the following figure. A voltage of about 2.1V is obtained by dividing the voltage of 3VDUAL through NPR16 and NPR17 to charge the NPC9 capacitor. When the battery is fully charged, it outputs P1V0_PCH_EN signal to supply power to the 1.05V power chip to turn on and output the 1.05V bridge. The multimeter measures that NPR16 has a voltage of 3.3V at the upper end and 0V at the lower end, and it is suspected that NPR16 is damaged at first.
On-line measurement shows that the resistance of NPR16 is 19.56 kω and that of NPR17 is 19.62 kω. The resistance is basically normal.
Therefore, it is suspected that the NPC9 capacitor is leaking. After removing this capacitor, it is plugged in to measure that there is a voltage of 2.181V at the lower end of NPR16, and the bridge power supply of 1.05V is perfect. Short-circuit the boot pin and start it immediately. At this point, the board is perfectly repaired.
