I need to replace a DC adapter for an old NAS that was lost to a power spike but I'm having a hard time identifying exactly the kind of connector.

This is the connector on the back of the NAS:

enter image description here

I have this universal adapter kit that I use temporarily:

DC adapter kit with multiple plugs

And after testing a few plugs I discovered this is the one I need:

enter image description here

The plug has the following specifications:

  • outer diameter: 5.5 mm
  • inner diameter: 3.0 mm
  • no pin inside the plug (the pin is in the NAS connector)

I don't want to keep using the kit and need to find a definitive replacement. However, I'm having a hard time finding one with these exact specs.

I would like to know:

  • Is this a standard size?
  • Is there an IEC-like code for it?

Any additional information is appreciated.

  • 2
    \$\begingroup\$ Are you sure that you have the right ID? 5.5mm OD with 2.5mm ID is a standard barrel plug size. I'd suggest you buy one of those and try it to see if it fits. \$\endgroup\$
    – user324996
    Dec 17, 2022 at 12:48
  • \$\begingroup\$ What's stopping you from looking at the connector on the original power supply, or using it with another power supply? \$\endgroup\$
    – Justme
    Dec 17, 2022 at 14:29
  • 1
    \$\begingroup\$ This is a standard barrel plug. They come in several sizes, though an ID of 3 mm is unusual. \$\endgroup\$
    – Hearth
    Dec 17, 2022 at 15:09
  • \$\begingroup\$ what are the dimensions of the original connector? \$\endgroup\$
    – jsotola
    Dec 17, 2022 at 18:59
  • \$\begingroup\$ @Justme the original connector melted due to the power supply failure but I'm sure it had these same specs because the plug from the kit fitted perfectly. \$\endgroup\$ Dec 17, 2022 at 22:50

1 Answer 1


You can search for DC power connectors at Mouser and Digi-Key and others and do a parametric search (or set a filter) on inner/outer size, gender, etc. to find the right size and type. Note that different lengths are sometimes also available.

  • \$\begingroup\$ Thanks for the reference, but alas I was not able to find this specific adapter. I'll keep using the plug from the universal adapter but this "investigation" has become a minor obsession of mine, any additional information or insight is greatly appreciated. \$\endgroup\$ Dec 17, 2022 at 23:00
  • \$\begingroup\$ It certainly is an odd one at that size. I did find this one link... elliottelectronicsupply.com/3-0mm-x-5-5mm-dc-coaxial-plug.html \$\endgroup\$
    – user324996
    Dec 17, 2022 at 23:08

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.