ASUS h61m-k does not display after startup, and does not run code for repair

ASUS h61m-k does not display after startup, and does not run code for repair

Motherboard model: ASUS h61m-k Rev: 1.03

Fault phenomenon: boot does not display, do not run code

Maintenance process:

A h61m-k Rev: 1.03 motherboard, the fault is boot does not display, replace memory, add independent graphics card, replace CPU, determine the motherboard problem.

According to the working process of the motherboard, it can be turned on without display. It mainly checks VCC,CLK, reset and code running. Because this motherboard is not designed with PCI interface, the conventional diagnostic card can not be inserted.

Do not show, from the simplest check VCC, all VCC are normal, CPU is also hot.VCC normally swips a BIOS first, but the BIOS downloaded from the forum still fails.Using oscilloscope to measure motherboard, first measure BIOS 1 pin.

ASUS h61m-k does not display after startup, and does not run code for repair Figure 1.

It can be seen from this figure that since the machine has not reached the point of code running, naturally there is no addressing, so it is necessary to measure and reset forward.

ASUS h61m-k does not display after startup, and does not run code for repair Figure 2.

Find Boardview, find the measurement point of pltrst ා, and measure 0V with multimeter. Therefore, the motherboard has not reached the reset step, and then continue to measure forward. Because the CLK of H61 motherboard is integrated into the bridge, the VCC part in front of CLK measurement is skipped.Since VCC is normal, all VCC are not reset normally,Then you only need to check two places, that is, the PG of CPU and pwrok of IO, because it is the reset condition of CLK, as shown in the figure:

ASUS h61m-k does not display after startup, and does not run code for repair Figure 3.

It can be seen from the figure that the PG of the CPU is 1.05v, and the VCC is the pull-up of the bus. Therefore, the VCC is normal, that is, all CPU power chips are working normally.

ASUS h61m-k does not display after startup, and does not run code for repair Figure 4.

Through Boardview, the PG of CPU is connected to the g-level of a small field transistor through a resistor. It can be seen from the above figure that VCC reaching level G is normal, which indicates that this line diagram is on. After checking through Boardview, it is found that two MOSFET control vrmpwrgd signal. This signal is the CLK reset condition for Nanqiao, and the measured value is 0V.

ASUS h61m-k does not display after startup, and does not run code for repair Figure 5.

ASUS h61m-k does not display after startup, and does not run code for repair Figure 6.
The problem has been found. The following MOSFET has 1.05v in G level, but 5V high level in D level, indicating that there is no conduction. The 5V high level makes the MOSFET above turn on, resulting in the vrmpwrgd not having VCC. Under normal circumstances, replace the following MOSFET, and wrmpwrgd can be pulled up successfully.

ASUS h61m-k does not display after startup, and does not run code for repair Figure 7.

As shown in the figure, the vrmpwrgd will be 3.3V after dismantling.

ASUS h61m-k does not display after startup, and does not run code for repair Figure 8.

BIOS’s first pin waveform, indicating that the addressing is normal, plug in the display, the machine normal display, maintenance is over.

ASUS h61m-k does not display after startup, and does not run code for repair Figure 9.