Qnap TS453 Semi Working Motherboard , though 12V to two disks only

[90Ninety]

Hi

I have a 453 Mini , two of the four Sata ports are not getting 12V . I am wondering if anyone has knowledge on hardware repair on these devices . I have attached an image of the board , it appears the Sata ports are powered in pairs , the right pair are working , left pair no voltage ( 0.2V)


I have tried tracing the 12V rail , though have not been successful . I am guessing there is a Transistor or Mosfet that is open

Any help , perhaps a schematic?


The board otherwise appears to work fine .. Boots up ,

[90Ninety]

I suspect , that this component 4955GM ( MOS?) is the culprit





. Since on Pin 1, 2 & 4 have 12V Then pins 7 & 8 go to the 12V on the Sata on the 2nd slot ( non working) .. Though I cant seem to find a trace to the 1st slot 12V . Perhaps I will replace this , then see ..


Also this looks suspicious ( WRA D33) , though not sure what it is, seems to be a much higher resistance compared to the others next to the working SATA ports


WRA D33

[90Ninety]

Seems the markings on the components are not clear .. Perhaps the alcohol wash removed them

Cant seem to find anything definitive on the marking I can see , what are 4955GM & WRA-D33 .. Unless I have recorded them incorrectly ?

[rogfanther]

You can try to deduce the circuit ( and pin voltages ) from the functioning pair of ports

[90Ninety]

I replaced the 4955M Power Mosfet , though this makes no difference . There is something stopping the mosfet from sending the 12V to the SATA port ..