ASUS b75m-Plus mainboard without reset repair

ASUS b75m-Plus motherboard is powered on, and the detection card is plugged in. The reset lamp is always on, and the motherboard is not reset. Replace the triode Q1 and start the machine normally.

ASUS b75m-Plus mainboard without reset repair

Motherboard model: ASUS b75m-Plus motherboard

Fault phenomenon: the main board has no reset

Maintenance process:

ASUS b75m-Plus mainboard without reset repair

ASUS b75m-Plus mainboard without reset repair Figure 1.

A ASUS b75m-Plus motherboard, the fault is that the motherboard is powered on, the detection card is inserted, and the reset lamp is always on. It is tested that the main VCC, CPU 1.13v, memory 1.5V, vccio 1.06v, vccpll 1.8V and bridge VCC 1.05v are normal. Basically, all VCC s are available.Test CLK, measure PCIe A13 A14, there is 0.4V or so VCC,CLK should also have CLK, if not reset, check the vrpg of CPU.Find Boardview in the forum,pin ut of pgc230.01 is normal.

ASUS b75m-Plus mainboard without reset repair

ASUS b75m-Plus mainboard without reset repair Figure 2.

Follow the circuit through an 8.2k resistor, the other end of the resistance controls onetriodeThe base stage of 0.9V VCC.

ASUS b75m-Plus mainboard without reset repair

ASUS b75m-Plus mainboard without reset repair Figure 3.

The collector of this triode has a 5V VCC and an emitter GND. This VCC is not pulled low. The problem is that the computer reset normally lights up after replacing Q1.

531;IMG_259

ASUS b75m-Plus mainboard without reset repair Figure 4.

Normally, the VCC should be pulled low, and then the Q2 cut-off is controlled. At this time, 3V VCC of R1 pull-up resistor can reach the bridge and inform the bridge that all VCC are ready and can be reset.

597;IMG_260

ASUS b75m-Plus mainboard without reset repair Figure 5.