ZOTAC gtx1050 graphics card does not display when turned on

Video card model: ZOTAC gtx1050 2gd5 thunder version PB

Fault phenomenon: the display card does not display when it is turned on

Maintenance process:

ZOTAC gtx1050 graphics card does not display repair Figure 1.
A ZOTAC gtx1050 2gd5 thunderbolt Pb graphics card, cleaning GPU and corrode.

ZOTAC gtx1050 graphics card does not display repair Figure 2.
Start to test several groups of diode value of VCC, and the test points are as follows:

ZOTAC gtx1050 graphics card does not display repair Figure 3.
The above values are basically the power on timing of this video card:
①5V_VddC U1 2 pin 2.7KΩ is normal
②1V8_VddC L15 2.4kΩ is normal
③NV3V3_VDDC  Q23 S pole 97Ω is normal
④NVVDD Q523 D pole 2.7Ω is normal
⑤PEX_VddC L16 5.7Ω normal
⑥FB_VDDQ Q594 D pole 180Ω normal
The tissue of VCC in the above six groups were normal. The test of VCC showed that ①, ② 5V and 1.8V were normal, while those of ③, ④, ⑤ and ⑥ were all 0V. The nv3v3 was checked by time sequence_VddC VCC is controlled by q23 NMOS tube, D pole is connected with pex3v3,VCC is normal, but output of S pole is 0V, test g pole must be 0V, it is g pole VCC is pulled down.Check the drawing for reference.

ZOTAC gtx1050 graphics card does not display repair Figure 4.

It is found that VCC of pin is composed of q18-q16-q20, and the printing silk is s1a5. These three are compound NPN double MOSFET.

ZOTAC gtx1050 graphics card does not display repair Figure 5.

ZOTAC gtx1050 graphics card does not display repair Figure 6.

After inspection, it was found that Q16 and Q18 had problems respectively. It was estimated that water damage corrode was broken and replaced with k6na4 directly.

ZOTAC gtx1050 graphics card does not display repair Figure 7.
After replacement,VCC is normal, and several groups of VCC are normal
①5V_VddC U1 2 pin 5.2V normal
②1V8_VddC L15 1.8V normal
③NV3V3_VddC Q23 S pole 3.3V normal
④Nvvdd Q523D pole 0.8V normal
⑤PEX_VddC L16 1.0V normal
⑥FB_VDDQ Q594 D pole 1.52v normal
Plug in the monitor and light up perfectly!

ZOTAC gtx1050 graphics card does not display repair Figure 8.

ZOTAC gtx1050 graphics card does not display when turned on