Need info:8-pin power supply

[sphzxcv 0]

Hi all.

Will appreciate assistance from members of the forum.

I have a 9-channel DVR by AVtech. Recently its power supply failed to function. I searched around for a replacement unit but ....

So I decided to custom make a power supply for the DVR.

The power supply I am making consist of 2 separate units, one supplying 12v and the other 5v.

Sounded simple, eh? But the output plug is a 8-pin plug and I need to figure out which pins are 12v and which are 5v.

Fortunately, the output supply comes with a diagram of the pins' output, showing the +12v and +5v pins. However, the -12v and -5v pins are indicated as GND only.

I need to know which of the GND pins are the -12v and which are -5v as the GND is not the common GND of a single supply. The pins concerned are pins 1, 2, 3 and 5 from the attached photo.

Will it make any difference if the -12v and the -5v are swapped?

A photo of the old power supply is attached.

 

The DVR is a 9-channel (JPEG format) non-network unit from AVtech.

 

Thanks for the assistance.

[Soundy 1]

I need to know which of the GND pins are the -12v and which are -5v as the GND is not the common GND of a single supply.

 

Why not?

[scorpion 0]

Before you tie the grounds of two separate power supplys together, then I would say only have one transformer feed power to both power supplys.

 

Or I would use an Isolation transformer.

 

 

 

Perhaps a computer power supply may be useful?

 

Here is a link to the AVTech power supply

http://www.weclonline.com/tchi/productdetail.asp?id=50122822

[DaveM 0]

I googled KY-05072 and found one for sale for $29.95. Unless you are looking for a project, it might be better just to buy the proper replacement supply.

[cachecreekcctv 0]

When a Power Supply is generating both 12vdc +, 12vdc - , 5vdc +, 5 vdc -, it is usually for powering a hard drive, as well as the Motherboard. You need to do a little searching for your particular PS. You might try to take a look at both Newegg and Tigerdirect, under Power Supplies for PC's. Both of these websites ( and many others I am sure), show the pin voltages of different Power Supply connectors to Motherboards. Yours might look like one of them. That would give you a starting point. Insure Polarity with your voltmeter. I have built CCTV power supplies ( 12 VDC) from PC power supplies, as they are UL Listed. Just add fuses (DIN mount), wiring, DIN rail, Nema enclosure. Don't confuse "ground" with "negative voltage" or "neutral". Good luck

[sphzxcv 0]

Thanks for the replies.

I've managed to sort out the connections. The DVR is working fine now.

[survtech 0]

Most power supplies of that type have common grounds, even if they have multiple ground pins. You can confirm that by doing a continuity test between the ground pins with a VOM or continuity tester.