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Electronics => Beginners => Topic started by: StuUK on October 17, 2016, 10:20:35 am

Title: Power Supply - Power/Current Question?
Post by: StuUK on October 17, 2016, 10:20:35 am

I've taken the attached power supply out of an old SKY box, the power supply works fine and could be very useful for something else but I've drawn a blank on trying to find any product info for it.

What i'd like to try and work out is what power/current I could expect to draw safely from the 5v/12v supply.

I suspect I'm missing a simple answer here but is there anyway of working this out?

Title: Re: Power Supply - Power/Current Question?
Post by: tron9000 on October 17, 2016, 10:35:08 am

I suspect there are surface mount componets on the other side of this board? may we have a photo on that side? quite close up so we can see any IC idents

Title: Re: Power Supply - Power/Current Question?
Post by: joseph nicholas on October 17, 2016, 10:57:15 am

It looks to be probably around 10 amps.  Try load testing it using your multi meter.  This can be done by short circuiting it through the 10 amps range for a few seconds. 

Title: Re: Power Supply - Power/Current Question?
Post by: Cliff Matthews on October 17, 2016, 10:58:54 am

Used in this product: http://electronics360.globalspec.com/article/3556/bt-vision-gen2-dvr-set-top-box-teardown (http://electronics360.globalspec.com/article/3556/bt-vision-gen2-dvr-set-top-box-teardown) author says it's 34 watts, so I'd guess both 12 and 5v rails can offer 2amps. There's at least 2 DC-DC convertors on PCB (left) likely ran 3.3v to the CPU and maybe 9v to th ethernet phy driver. (http://extranet.globalspec.com/InfoPreview/GlobalSpec/E360/Teardowns/BT_Vision__(Gen2)_DVR_Set_Top_Box_(iSi)/BT_Vision__(Gen2)_DVR_Set_Top_Box_(iSi)_-_Main_PCB_Top.jpg)
Similar box shown here: (http://4.bp.blogspot.com/-ZXaYIqOrFNA/UYDZBfv_MpI/AAAAAAAAAHk/ItrP7FckcYg/w1200-h630-p-nu/dad-shows-kids-inside-an-old-sky-box.png)

Title: Re: Power Supply - Power/Current Question?
Post by: StuUK on October 17, 2016, 11:08:46 am

Quote from: tron9000 on October 17, 2016, 10:35:08 am

I suspect there are surface mount componets on the other side of this board? may we have a photo on that side? quite close up so we can see any IC idents

Nothing, it's a single sided board.

Title: Re: Power Supply - Power/Current Question?
Post by: StuUK on October 17, 2016, 11:10:37 am

Quote from: Cliff Matthews on October 17, 2016, 10:58:54 am

Used in this product: http://electronics360.globalspec.com/article/3556/bt-vision-gen2-dvr-set-top-box-teardown (http://electronics360.globalspec.com/article/3556/bt-vision-gen2-dvr-set-top-box-teardown) author says it's 34 watts, so I'd guess both 12 and 5v rails can offer 2amps. There's at least 2 DC-DC convertors on PCB (left) likely ran 3.3v to the CPU and maybe 9v to th ethernet phy driver.

Yes, that's the board, in fact I think it was a BT box not SKY box as I mentioned above.