Seller Note “This card just displays a black screen on turning pc on sold for parts only”
Summary
- Appears to be missing the VMem rail.
- Resistances
- VCore – 12.4
- VMem – 104.8
- PEX – 235
- 5V –
- 3.3V – 10.8K
- 12V – 11K+
- Missing VMem rail – replacing the buck converter EM5303A fixed this
- Card is working
Investigation into Key Components
VCore PWM
I think this is a Richtek RT8809BZQW https://www.richtek.com/assets/product_file/RT8809A=RT8809B/DS8809AB-02.pdf
It appears to drive a pair of MOSFETS (TBC)
Power Management
Its APL3516C https://datasheetspdf.com/pdf-file/761940/ANPEC/APL3516/1
Missing VMem Rail
Its EM5303A https://datasheetspdf.com/pdf-file/807405/CYStechElectronics/EM5303A/1
This also appears to drive a pair of MOSFETs (TBC). I need to check this in more detail since VMem is missing.
PIN 5 – VCC is 12v
PIN 7 – EN is 5v
So, on EM5303A
pin 2 (UGATE) -> Gate of Q13 (SM3119NA N-Channel Enhancement type MOSFET)
pin 4 (LGATE) -> Gate of Q10 (SM3116NA N-Channel Enhancement type MOSFET)
Together these components, with a single inductor and capacitor, form the VMem VRM. My guess is that the PWM controller EM5303A could be faulty since it has EN and VCC are present. On a working K2000D, a PWM signal can be seen on the gate of Q10 and Q13, and a VMem of 1.37V is present. This was correct! Replacing EM5303A from a donor card has fixed the VMem rail and the card seems to be working now 🙂
Testing
- MATS 10Mb, 25Mb, 50Mb – passed
- Kombuster (some), the card worked by is not suited or powerful enough for this kind of benchmark
- 2 x Display ports and DVI – working
Hello.
I got a GV-N7800C-3GD in Australia and its artfacting, MATS throws multiple assertion failures can you plz help.
Board is very clean had hard look under microscope no corrosion anywhere.
Hi, ok, sure. Has MATs indicated a failing memory bank in the table of results e.g. A1, A0 etc? Also, do you know the discord (and YouTube channel) Learn Electronics Repair? It’s a good place to chat about repairs, there is a channel on there for 7 series cards. My avatar is Rupo7 on there. Plus there are others who can help.