Page 65 - GIGABYTE Service Manual-v3.0-110101

3.2.10 VCC3_DAC

Solution:
In figure VCC3_DAC circuit, a component includes MOS Transistor and R, C. The

output pin 1 VCC3_DAC 3.3V depends on input pin 3, 3VDUAL and control gate pin 2
from the voltage +12V. If VCC3_DAC fail , we can measure control gate pin 2
voltage +12V or resistor R146 , otherwise measure impedance on all pins of Q20 to
confirm whether MOS Transistor is defected.

Figure 3-19: VCC3_DAC

3.2.11 DDRVTT

Solution:
In figure DDRVTT circuit, components include regulator and R, C. The output pin 4
DDRVTT 0.9V depends on input pin 1 DDR18V and Reference pin 3 from the divided
voltage of DDR18V, and from U14 which is three voltage channel console. The

uP6262 is a high precision voltage console consisting of three sets I2C programmable
current DACs. If DDRVTT fails, we would measure DDR_VTT_REF pin 3 voltage or
impedance, and also measure R441, R443 to check if any broken. If not, measure U14
after measuring all pins of U12 to confirm IC defect or not.

Figure 3-20: DDRVTT

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