Is it possible that a USRobotics modem needs a 20V AC power supply?

[Bob Crabtree]

Strange question but...

...I have a US Robotics external modem (a POTS modem, not broadband) but no power supply for it.

So, I filled out a form on the company's web site and got an emailed response telling me that what's needed is a unit that puts out 20V AC and 5A.

I've got no issues with 5A and could just about accept that it might be 20V but AC?

So I got back to USR and respectfully asked if it really was AC, and the answer came back, "Yes".

This is a pretty old unit - perhaps six or seven years old (model is a 015663-02) - but is it really likely this is going to require an AC power supply?

Why am I bothering? Well, it's because I know someone who could use an external modem and, if a power supply isn't overly expensive, then I can pass over this US Robotics model.


TIA

Bob

[listy]

does it not tell you on it how much v its needs?

i got modem(think was that one) like that off ebay (didnt work) but not sure if power brick got saved from the bin @ last move

tbh i cant see it neededing ac btw but i could be wrong

[Bob Crabtree]

No, there's nothing at all on the unit about what power supply it needs and, though I managed to download a manual, there was nothing there either.

As you can understand, I'm dubious about the stated AC power requirement - and, also, I can't see anyone selling anything vaguely suitable, irrespective of price.

Not strictly true, I've seem a lab-bench variable power supply for the price of about six old-style external modems, but nothing appropriate.

[Workaholic]

Strange question but...

...I have a US Robotics external modem (a POTS modem, not broadband) but no power supply for it.

Is there an actual diagram on the bottom of the unit?
This would clear the mess up as I bet the tech support meant AC input.....

P.S. if its AC you'll see the sine wave, if its DC it's 2 lines (like an equal sign =) but with the one of them dotted!

[Bob Crabtree]

Is there an actual diagram on the bottom of the unit?
This would clear the mess up as I bet the tech support meant AC input.....

P.S. if its AC you'll see the sine wave, if its DC it's 2 lines (like an equal sign =) but with the one of them dotted!

Nope, nothing of the kind anywhere on the modem and, as I said, I actually double-check with the company's support people and they insisted that it is, indeed, AC.

Me, I think they were wrong both time but stranger things have happened.

[MadduckUK]

have you got the full name?

[Bob Crabtree]

have you got the full name?

USRobotics 56K Voice External RS-232 (U.K.)

Model is 015663-02.

[MadduckUK]

On Sun, 28 May 2006 11:55:33 +0200, Juergen Bertram <jb@bronnen.belwue.de>
wrote:

>Hello everybody,
>
>
>the power supply of the modem got lost:
>
>3COM U.S.Robotics, 56K Professional Message Modem, built in 1998
>
>and I need some technical data:
>
>- Typ of Power (AC or DC)
>- Voltage
>- Power (mA or VA)
>
>Is anybody out there, who can help?

Ja.

ist 9V DC 300mA.

i know its not the same, but its a US Robotics modem and its old. so id put money on it being right

also: surely if it WAS AC (into the modem that is) it wouldnt have an adapter at all, and instead just have a lead.

[Bob Crabtree]

i know its not the same, but its a US Robotics modem and its old. so id put money on it being right

also: surely if it WAS AC (into the modem that is) it wouldnt have an adapter at all, and instead just have a lead.

I'd bet that the power requirement is indeed DC, which is why I started this thread.

However, the power that comes out of the mains is 240V, not 20V, so if the requirement were in fact for 20V AC, then, no, it would not just have a lead (here I'm presuming you mean a lead that plugs into the mains), it would have a step-down transformer that converts the 240V AC to 20V AC.