modem help

From: Tothwolf <tothwolf_at_concentric.net>
Date: Fri Oct 25 01:38:01 2002

On Thu, 24 Oct 2002, Patrick Rigney wrote:

> Hmmmm... I have two Sportsters. One is a 33.6 model (product code is
> 000839-07), which uses a 9VAC supply, 1000ma, labeled USR part number
> 1.015.1286. The other one is an older 28.8 model (product code is
> 000839-01), and it uses a 20VAC (!) supply, 500ma, labeled p/n
> 1.015.1202-B. Neither modem has any marking stating its power
> requirements. Sweet. The plugs on both are very similar, both black
> banded 5.5mm female, but the center hole is 2.1mm on the 20V supply,
> 2.5mm on the 9V supply. Just a quick peek at the Jameco catalog looks
> like their equivalent part number for the 9V supply is 157041 for $5.95
> (caveat emptor... I can't confirm this is a working replacement, it just
> looks right).

Strangely enough, US Robotics made two different Sportster 28.8 modems.
I've only seen a handful that used the 20VAC supply, so I generally don't
worry about them. At least you can't plug the 20VAC supply into the modems
that need 9VAC. I doubt that plugging a 9VAC supply into the 28.8 would
hurt it, but I doubt it would work properly. AFAIK, all of the 33.6, 14.4,
and 9600 Sportsters used 9VAC, and I believe most all of the
4800/2400/1200 Sportsters did too. I think some of the really early 1200s
used yet another supply.

US Robotics/3Com made two distinctly different versions of the 33.6
Sportster (but both use the same supply). One has an Intel flash RAM chip
in it for firmware upgrades (these are 56K X2/V90 capable if you can still
find the proper firmware, it wasn't commonly available). The other has a
ROM in it, and is pretty much stuck at 33.6. I have a number of the ROM
type 33.6 modems somewhere, and I've often wondered if they could be
modified to support the flash chip.

USR also made several versions of the later 56K modem, but AFAIK, all of
them can be flash upgraded in one way or another to support the latest 56K
X2/v90 protocols. Some (although all should be) upgradeable to v92, but
USR wants to charge for the upgrade on some of the units.

If you really want to see some power supply weirdness, have a look at
Hayes modems, specifically the "classic" aluminum shell ones.

I've used *tons* of modems made by USR and Hayes over the years...

-Toth
Received on Fri Oct 25 2002 - 01:38:01 BST