Gigabyte GA-H61M-DS2 REV 3.0 The Motherboard Does Not Power On Repair

 

Motherboard Model: GA-H61M-DS2 REV 3.0

Fault: The motherboard does not power on.

Repair process:

　　A Gigabyte GA-H61M-DS2 motherboard, the initial failure of the motherboard does not power on.

    The motherboard's appearance showed no obvious signs of damage or burns. Plug in the power supply and test without triggering. Go straight to the switch pin and measure 1.2V. Observe that a 6-pin tube is found near the switch pin. Turn off the power and measure that this tube is connected to the switch pin. After removing it, measure 3.3V.

    Triggered at boot, the motherboard keeps restarting without running code.
　　

    After measuring each power supply, the memory power supply is normal, the bridge power supply is normal, the CPU VTT is normal, and the CPU power supply is not. Check the drawings to search for the DU1 CPU power supply chip, ISL95836.

Check pin 25 and 26 VDD VCCP, 5V is normal;
check pin 9 VR_ON - VTT-PWRGD is normal;
check pin 5, 6, 7 and 8 1.05V is normal (VTT pull-up);
check pin 10 NTC temperature detection is normal.
　　

Directly replace the power supply chip, and then turn on the CPU to power the CPU, but the code still does not run after restarting.

Search PLTRST in the drawing and find the platform reset renamed -PFMRST. Go to the IO68 pin and make IO 65 and 64 pins send out PRST1-, PRST2- and rename it -PFMRST1, -PFMRS2 through the resistor. All three measurements are normal.

    Find the CPU reset CPUURST, which is controlled by -PFMRST1 to turn on Q28 and pull down the second pin of Q29 to cut off Q29. VCC3 divides the voltage through R222 and R223 to get a voltage of about 1.1V and renames it -CPURST .The measurement is normal.

Since everything is normal, I refreshed the BIOS and the fault persisted.

　　Check the IO voltage. Pin 1 is normal, pins 126 and 127 are 2.0 normal, pin 128 is 2.8V. Pin 128 is divided by VCC3, but the two voltage dividing resistors on the motherboard are not there. Turn on pin 128 and measure it. It is found that 2.8V is divided by VCC3. IO is issued, which is normal for the time being.

Check the PLL voltage to be 1.8V, which is normal.

VRMPWRGD, normal.

I found the notes and opened the timing and learned that after the CPU is reset, it goes to the bridge through the DMI bus, and the bridge reads the BIOS through the SPI bus.

 

Welded the BGA, plugged it in and turned it on. The code started to run and the display came on, but it didn't trigger when I turned it off and on again. Oscilloscope measures crystal oscillator, no waveform. I replaced the crystal oscillator directly and everything turned on normally

Happy Repairing !