Gigabyte radeon RX 6700 XT graphics card unrecognized repair.

Graphics card model:Gigabyte radeon RX 6700 XT graphics card
Symptoms: The graphics card is not recognized.
Maintenance process:
Receive a piece Gigabyte Radeon RX 6700 XT Graphics card, graphics card does not recognize the card on the computer.
According to the power-on sequence of AMD graphics card: 12V-5V-1.8V-0.8V-0.9V- memory VCC- core VCC, test each VCC VCC.
+12V_BUS, +3.3V_BUS are normal, 1.8V 0 is abnormal, and the first fault point is locked.

Gigabyte radeon RX 6700 XT graphics card unrecognized repair figure 1.
1.8V is generated by U4708, chip model MPQ8633A ,VCC is normal, and it is not turned on.

Gigabyte radeon RX 6700 XT graphics card unrecognized repair figure 2.
Generally, 1.8V is turned on by 3.3V pull-up, from 3V Jump wire to 8 pin of the chip, which is artificially high and repairs 1.8V.

Gigabyte radeon RX 6700 XT graphics card unrecognized repair figure 3.

Gigabyte radeon RX 6700 XT graphics card unrecognized repair figure 4.
Power-on test still does not recognize the card, and continue to measure each VCC according to the time sequence.
0.8v bus VCC 1.0V,0.9v auxiliary VCC VDDCI 1.0V, and memory VCC 1V VCC are normal.

Gigabyte radeon RX 6700 XT graphics card unrecognized repair figure 5.
VPP 1.8V is normal, GPU internal memory control module VCC+VDDCR_SOC 1.0V or so, core VCC 1V or so is normal, and VCC is basically all out.

Gigabyte radeon RX 6700 XT graphics card unrecognized repair figure 6.
Next, measure whether PCIE CLK is reset and Crystal of graphics GPU is shaken. It was found that A11 sent 3.3V to reset VCC.

Gigabyte radeon RX 6700 XT graphics card unrecognized repair figure 7.

Gigabyte radeon RX 6700 XT graphics card unrecognized repair figure 8.
The reset of CLK has been satisfied, and the card is still not recognized after power-on. After checking the drawings, we know that the reset of the PWM chip in the core of this 6700XT graphics card is directly obtained from A11, and it is necessary to reset the first PWM control chip through an AND gate, and then generate a set of CPU VCC.08V similar to that of the 8th generation notebook for running time sequence. Fix the PWM reset first.

Gigabyte radeon RX 6700 XT graphics card unrecognized repair figure 9.

Gigabyte radeon RX 6700 XT graphics card unrecognized repair figure 10.
Replace U502, test 1 pin 3.3, 4 pin 3.3, power on and boot the system auto power off,pin.
On the oscilloscope, if the waveform is found to be faulty, replace the black Capacitor on the left side of the graphics card.