NVR Repairs

[aabs]

Hi All,

I recently upgraded my Dahua NVR4108-4SK to a new NVR5216.
Following the upgrade I sold my working NVR4108-4SK on ebay.
However the buyer reported that the NVR did not work on arrival and requested a refund which I have done (although I knew it was working when I sent it out).

Now I have the unit back there is no voltage at the fan or the HDD. The LEDs do no light but a faint clicking can be heard from the PCB.
Power at DC power adapter output confirmed 12V DC
Not sure what the ebay buyer has done to it many possibilities, faulty HDD fitted, reversed polarity or failed firmware upgrade.

Anyone have any schematics or recovered an NVR displaying these symtoms?

 

[IAmATeaf]

Or they’ve swapped it and sent back their non working? Is it the same serial number?

Now that the conspiracy stuff is out of the way, is the power supply built in or via an external block?

If internal then there is normally a startup capacitor which if it goes bad will stop the unit from powering up but once it’s running it will keep running until it’s powered off.

 

[aabs]

External US power adapter.
As in UK I suspect buyer matched up UK power adapter but with different voltage or polirity.
Checked MAC address of board on my router log and yes it is the original PCB.
There is a start up cap but dont know the rating