I have devices like USB hubs that are separated from their AC adapters. How do I tell which adapter they use?

Question

I have lots of adapters that indicate different voltages--I don't know which ones are safe to use with my device--can the wrong adapter damage my equipment?

Answer 1

Yes, the wrong adapter can damage your equipment. The first problem is that some adapters are AC and some are DC. AC adapters usually use show the voltage with a letter S on it's side next to it (representing an AC sine wave). DC adapters usually show the voltage with a straight line and a dotted line above it. The piece of equipment should match the same settings and should be marked the same.

The next problem is obviously the voltage, but hopefully this is marked on the adapter and the box. Similarly, you'll need to check the current rating. The PSU must have a higher rating than the device, hopefully they will be marked and match.

The final problem is polarity. For AC this doesn't matter, but for DC the output should be of the correct polarity. Unfortunately there is no standard but if you pug in the wrong polarity PSU you could blow up the equipment if it's not got any protection. Usually though they are protected or don't suffer any damage so long as it's not prolonged and usually if the power led doesn't light up its the wrong polarity.

If you're unsure, you would be best looking for details of a manufacturer's website and checking the PSU with a meter, but most PSUs read higher off load so don't worry too much if it's a few volts higher.

Hopefully, by the time you've checked them most have particular sockets and only a few will be able to fit in more than one device.

In the past, I've used a cheap variable power supply to find out what something runs off (poundshop specials!). Set it as low as it will go and plug it in to the device. if the led doesn't light, flip the polarity. If it still doesn't light, put the voltage up one step and repeat. Eventually the led will light so you'll know the polarity and then you can check if it works at that voltage or whether it needs to be slightly higher. I've never blown up anything using this method. You can then check this against your proper adapters to find the correct one.

Finally, put a sticky paper label on each one and either number them and put a similar number on your device or write on what they're for.

Good luck!

Answer 2

It's simple really - the hub pulls power from your computer, but also pulls power from the adapter. The current required to run the hub electronics is pretty low, along with things like wired mice. Devices like printers have their own power supply so they don't rely on the power coming from the hub. Depending on power requirements for your devices you could quite easily run a USB keyboard, mouse, pendrive, printer and scanner without overloading the USB port that your hub is connected to. Try plugging in nothing but a USB powered scanner and a 2.5" external hard drive and you'd certainly have problems. Best to run with the AC adapter, unless you can prove that the total power drain for all devices (including the hub) is less that 450mA (USB provides 500mA per port).

Answer 3

Check the label of both the devices and adapters one at a time. After you matched the watts of adapter and device, make a note there if you want.

Answer 4

Next to each female connection there should be three little dots connected by two lines and the polarity of the juice. Check those to the rating on the adapter and yer good.

Answer 5

Usually there is a label on the AC adapter that declares the manufacturer 'Canon, Toshiba, ect'.

Answer 6

Trace the wire or unplug them one at a time and see what goes off.