Asus ROG Z490 mainboard is not repaired by CPU VCC

Main board model: ASUS ROG STRIX Z490-R GAMING main board

Malfunction: CPU VCC does not appear on the motherboard.

Maintenance process:

An ASUS ROG STRIX Z490-R motherboard, without CPU, without CPU VCC, without CPU VCC, without CPU VCC chip is invalid.multimeter measurement, only CPU VCC and VCC can’t be reset, but also come out. Check whether the CPU pin pin is in good condition, and test Capacitor around the bridge, and find that one is out of power. Compared with the good board, the VCC is 1.24 V, the VCCD PHY _ 1p24 is not in standby, and it is not in startup, and the fault of CLK South Bridge remains the same.

ASUS Rog z490 motherboard does not output CPU power supply Figure 1.

It was found that PCH_PLTRST came out at 3.3V, and the reset on the graphics card slot did not go the same way as the reset of peripherals. Measure the reset of graphics card at 0V, and the reset Diode value is normal on the graphics card slot turned out to be Short circuit after 7408 gates. The reset pin of 7408 was very low to diode value, and the reset current of pin was close to 180 mA.

ASUS Rog z490 motherboard does not output CPU power supply Figure 2.

ASUS Rog z490 motherboard does not output CPU power supply Figure 3.

Turn on IO pin and reset Diode value is normal after pin, and directly change IO to solve the problem. Because the overload 7408 has been slightly damaged for a long time, the output is only 2.7V after changing IO, and the VCCIO startup measurement is normal at 0V.