Polarity of DC input on Ubee U10C018 Modem?

[deancoulter]

My cat chewed our cable modem's electrical input wire in two and dragged the plug off out of sight. I took the power adapter and modem to Radio Shack where I bought the proper power plug for the modem. I have a volt-ohm meter and can solder the plug on the cord, but I don't know the polarity of the plug. Is the center conductor of the plug positive or negative relative to the barrel of the plug?

 

[Pyree]

Can you find the polarity on the adapter. There is usually a half little circle with a dot symbol and an line pointing to the half circle and the dot shows the polarity.

Then there are AC/AC power adapter and you don't have to worry about polarity.

Most power adapter I encounter have positive inside and negative outside.

 

[mythunder]

Can you find the polarity on the adapter. There is usually a half little circle with a dot symbol and an line pointing to the half circle and the dot shows the polarity.

Then there are AC/AC power adapter and you don't have to worry about polarity.

Most power adapter I encounter have positive inside and negative outside.

My cable modem takes a 10 VDC, 1 Amp power adapter (modem's label even specifies that), but I can't find anywhere that tells me the polarity on the plug. The modem's circuit board doesn't specify polarity. The manufacturer doesn't maintain a technical questions desk and the cable company using the modem demands more information about me than I am willing to devulge.

I'll investigate your suggestion that, by convention, DC adapters all have positive inside and negative outside. I considered the possibility that DC adapters comform to some standard as you suggest, but haven't tried to confirm or deny the possibility.

Certainly, even if such a convention does exist, the modem's manufacturer isn't duty-bound to follow. The manufacturer could specify a DC adapter that goes against such a convention. I don't know why that might be the case, but such a decision by the manufacturer is possible.

Thanks for your suggestion. I'm going to check it out.