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iCraft GTX650 graphics card core has no power supply
Graphics card model: iCraft gtx650
Fault phenomenon: there is no power supply to the graphics card core
Maintenance process:
The fault of a iCraft gtx650 graphics card is that the core of the graphics card has no power supply, and the core power supply chip is rt8809bzqw.
Test the diode value of several groups of VCC
1、5V_VCC = 6.1m Ω, normal
2、GPU_VCC = 10 Ω normal
3、DDR_VCC = 280 Ω normal
4、PCI_VCC = 340 Ω normal
All the above test results were normal.Four groups of VCC have been tested on the computer. Except for 5V, other groups have no output
5V_VCC is normal. 
No power supply for the core of Mingyu gtx650 graphics card figure 1.
GPU_VCC 0.359v is low, normal is 1V or so. 
No power supply for the core of Mingyu gtx650 graphics card figure 2.
DDR_VCC 0V has no output. 
No power supply for the core of Mingyu gtx650 graphics card figure 3.
Pci-vcc 0V has no output. 
No power supply for the core of Mingyu gtx650 graphics card figure 4.
The VCC core circuit is not locked properly after the initial test.
The core VCC chip is rt8809bzqw, and the printing wire is 08 EF 
No power supply for the core of Mingyu gtx650 graphics card figure 5.
No power supply for the core of Mingyu gtx650 graphics card figure 6.
No power supply for the core of Mingyu gtx650 graphics card figure 7.
First,VCC 18 pin is VCC 12V VCC, 17 pin is 5V VDD VCC, the test results are normal. 
No power supply for the core of Mingyu gtx650 graphics card figure 8.
No power supply for the core of Mingyu gtx650 graphics card figure 9.
The normal condition of 3 pin en pin should be above 1V and the test result is normal. 
No power supply for the core of Mingyu gtx650 graphics card figure 10.
Then test the GPU VCC up and down MOSFET. The core of the card is two-phase VCC. 
No power supply for the core of Mingyu gtx650 graphics card figure 11.
No power supply for the core of Mingyu gtx650 graphics card figure 12.
The diode value in the left group was 1.2k Ω, while that in the right group was only 227 Ω. It was obvious that diode value was abnormal.
No power supply for the core of Mingyu gtx650 graphics card figure 13.
Change the chip directly, test on the computer, all VCC values are normal.
GPU_VCC 0.98v normal
DDR_VCC1.42V normal
PCI_VCC 1.0V normal
Computer test,Normally booting up, troubleshooting. 
No power supply for the core of Mingyu gtx650 graphics card figure 14.
