12v barrel connector/smoking modem

[Johnny Ruin]

I just moved and when I plugged in my modem a thin stream of white
smoke started coming out of the modem. I quickly unplugged it. I
noticed that the power cable I'd plugged into the modem wasn't the
original that came with Arescom modem. I tried what I assume is the
correct power cable and it continued to smoke.

I have more than a few cables with these ...I'll call them 12v barrel
connectors (please if you know the proper name let me know). I don't
understand electricity the way I should so reading the specs on the
cables isn't something I excel at. But, the specs on the cables seem
to vary . They all say 12v, but some have 1A, 1.5A, 10w ... My
question is this, is it proper to assume that I can use any cable with
this type of connector with my modem?

 

[meerkat]

I just moved and when I plugged in my modem a thin stream of white
smoke started coming out of the modem. I quickly unplugged it. I
noticed that the power cable I'd plugged into the modem wasn't the
original that came with Arescom modem. I tried what I assume is the
correct power cable and it continued to smoke.

I have more than a few cables with these ...I'll call them 12v barrel
connectors (please if you know the proper name let me know). I don't
understand electricity the way I should so reading the specs on the
cables isn't something I excel at. But, the specs on the cables seem
to vary . They all say 12v, but some have 1A, 1.5A, 10w ... My
question is this, is it proper to assume that I can use any cable with
this type of connector with my modem?

Incorrect.
You needed the correct supply for the modem !.
The `barrel` plugs can have 2 different polarities +-, or -+.
It sounds as though you`ve blown your modem.
Sorry `bout that.

 

[GT]

I just moved and when I plugged in my modem a thin stream of white
smoke started coming out of the modem. I quickly unplugged it. I
noticed that the power cable I'd plugged into the modem wasn't the
original that came with Arescom modem. I tried what I assume is the
correct power cable and it continued to smoke.

I have more than a few cables with these ...I'll call them 12v barrel
connectors (please if you know the proper name let me know). I don't
understand electricity the way I should so reading the specs on the
cables isn't something I excel at. But, the specs on the cables seem
to vary . They all say 12v, but some have 1A, 1.5A, 10w ... My
question is this, is it proper to assume that I can use any cable with
this type of connector with my modem?

I think the white smoke answered that one for you! You need the correct
power going into any device. Too many volts (V) or too much current (A) can
damage any electrical device.

http://tinyurl.com/2h6ks4

GT

 

[Johnny Ruin]

Thanks to both of you for your responses. I figured it was over for
the modem.... just wasn't sure if it might been something in the move
(snow/dropping it). It also seems ... idunno. I know I'm lame for
doing this to my modem, but it's kind of lame they're built that
way. Also lame the cords that don't indicate what product they came
with. I'll have to learn to check polarities that each piece of
equipment needs and compare to the cables. Anything other than
polarities I should be checking?

 

[DaveW]

NO. You have to use the adapter that has the EXACTLY CORRECT electrical
specifications for the device that will be powered. Guessing at which one
is incorrect.

 

[Calab]

Thanks to both of you for your responses. I figured it was over for
the modem.... just wasn't sure if it might been something in the move
(snow/dropping it). It also seems ... idunno. I know I'm lame for
doing this to my modem, but it's kind of lame they're built that
way. Also lame the cords that don't indicate what product they came
with. I'll have to learn to check polarities that each piece of
equipment needs and compare to the cables. Anything other than
polarities I should be checking?

They ARE marked...

The modem should have a label on it stating the voltage, amperage and
polarity required. The transformer will have a similar marking on it.

 

[kony]

They ARE marked...

The modem should have a label on it stating the voltage, amperage and
polarity required. The transformer will have a similar marking on it.

Unfortunately some gear doesn't have the voltage, amperage,
or polarity marked on it. Some of them don't even have this
spec in their manuals. The PSU does usually have at least
some if not all of this info on it but that doesn't do much
good if you don't have the psu or can't remember which one
it is. A sticker placed on the gear and PSU identifying
them can come in handy. Masking tape and a marker will do
in a pinch.

 

[kony]

I just moved and when I plugged in my modem a thin stream of white
smoke started coming out of the modem. I quickly unplugged it. I
noticed that the power cable I'd plugged into the modem wasn't the
original that came with Arescom modem. I tried what I assume is the
correct power cable and it continued to smoke.

I have more than a few cables with these ...I'll call them 12v barrel
connectors (please if you know the proper name let me know).

Barrel connector is a term often used. Are you certain the
modem uses a 12V supply? Are you certain it is DC, not AC?
It probably is, since it appears to be a broadband modem as
most modems that use 12V AC were analog dialup types.

I don't
understand electricity the way I should so reading the specs on the
cables isn't something I excel at. But, the specs on the cables seem
to vary .

What do you mean by "on the cables"? Ok, reading further I
think by cables you mean power supply.
Is there a spec in the modem manual for the voltage it uses?
Is there a marking on the back of the modem for the barrel
connector polarity? If not, "usually" the inside of the
connector is positive and the outside negative, but it's
safer to have some confirmation of this instead of only
assuming it. Often the PSU itself will have a label which
shows the connector polarity.

They all say 12v, but some have 1A, 1.5A, 10w ... My
question is this, is it proper to assume that I can use any cable with
this type of connector with my modem?

The current doesn't necessarily matter, meaning too low a
current shouldn't cause smoke and too high a current would
not matter with a regulated PSU, but it might if the wrong
type of unregulated PSU were used and the design needed
close to 12V, could not stand much higher. So in some
cases a different PSU can be substituted with different
current ratings, but it can't be assumed universally true.


Let's use the term power supply instead of cable.
Your original power supply, if it is 12V, might be a
switching, regulated type which means it always outputs very
close to 12.0V, it might be a little higher or lower but not
by much.

If you used an unregulated power supply, one of the common
wall warts with only a large transformer, bridge rectifier,
and smoothing capacitor, then it's output will vary based
upon it's current capability and the current drawn by the
modem. It might float to a higher voltage than 12V due to
too little load, as high as roughly 16V.

This is what I suspect happened, either it was an
unregulated PSU that put out a voltage too high, or the
polarity was wrong on the connector. Often gear like this
has a polarity protection on the PCB, a series diode to
protect against this, but not always.

Regardless, it seems the modem is now damaged. You might
see if there is a reset switch you can use to try to reset
it using the original PSU, but otherwise unless you can
repair it yourself then it has to be replaced.

 

[Brian Cryer]

I think the white smoke answered that one for you! You need the correct
power going into any device. Too many volts (V) or too much current (A)
can damage any electrical device.

Agreed on all points except too much current - I'm not an electrical
engineer but my understanding is that polarity and voltage are the key items
to match. The adapter otherwise needs to be capable of providing at least as
many amps (or milliamps) as the device wants to draw. The thing to note is
that the power supply is rated up to however many amps, but it is the device
that dictates how many amps it draws. So plugging a 12volt 500mega-amp power
supply (if there were such a thing) wouldn't harm a 12volt device that only
drew 0.5amps.

So when looking for an alternative power supply (oh, and I agree totally
that the white smoke says its too late for that), match the voltage and
polarity but aim for one that is capable of providing at least as many amps
as the device needs.

 

[Johnny Ruin]

Thanks to everyone for the responses. I've ordered a new modem.
When I get it I'll be sure to mark the power cord with the name of the
modem (if it isn't already). Beyond that, I'll have to read
electricity for dummies or some such text in my spare time. Thanks
again.

 

[Guest]

I just moved and when I plugged in my modem a thin stream of white
smoke started coming out of the modem. I quickly unplugged it. I
noticed that the power cable I'd plugged into the modem wasn't the
original that came with Arescom modem. I tried what I assume is the
correct power cable and it continued to smoke.

I have more than a few cables with these ...I'll call them 12v barrel
connectors (please if you know the proper name let me know). I don't
understand electricity the way I should so reading the specs on the
cables isn't something I excel at. But, the specs on the cables seem
to vary . They all say 12v, but some have 1A, 1.5A, 10w ... My
question is this, is it proper to assume that I can use any cable with
this type of connector with my modem?

1A is far more than adequate, and very likely even 0.5A would have
worked.

I think your problem was either polarity or AC used in place of DC.
Most devices need DC of the correct polarity. Normally the outer part
of the barrel is negative, or ground, while the hole is positive, but
some devices require the opposite. Here's how barrel plugs are
labelled, in this case the "-" is he outer side, the "+" the center
hole:

http://img510.imageshack.us/img510/893/powerplugie4.jpg

 

[w_tom]

Beyond that, I'll have to read electricity for dummies or some
such text in my spare time.

You should have already read it. Kony posted a good little
explanation. No spare time needed. You already read it. But did you
stop for a minute and grasp it. If not, important knowledge for any
human is written there. Spend far less time than it took to post -
and grasp Kony's simple description. Maybe one minute would have saved
you how many dollars?

 

[kony]

I just moved and when I plugged in my modem a thin stream of white
smoke started coming out of the modem. I quickly unplugged it. I
noticed that the power cable I'd plugged into the modem wasn't the
original that came with Arescom modem. I tried what I assume is the
correct power cable and it continued to smoke.

I have more than a few cables with these ...I'll call them 12v barrel
connectors (please if you know the proper name let me know). I don't
understand electricity the way I should so reading the specs on the
cables isn't something I excel at. But, the specs on the cables seem
to vary . They all say 12v, but some have 1A, 1.5A, 10w ... My
question is this, is it proper to assume that I can use any cable with
this type of connector with my modem?

1A is far more than adequate, and very likely even 0.5A would have
worked.
[/QUOTE]

While I agree it probably is using closer to 500mA than
1000mA, it is definitely using enough power that a 500mA PSU
would be very little margin if any... normally you don't
want to use a PSU barely capable of the load. With the
little brick switching types this can sometimes also cause a
failure to start probably - they just start making a ticking
noise and the output is terribly erratic, making an
undersized switching supply more risky than an undersized
unregulated type.

 

[Plato]

I just moved and when I plugged in my modem a thin stream of white
smoke started coming out of the modem. I quickly unplugged it. I
noticed that the power cable I'd plugged into the modem wasn't the
original that came with Arescom modem. I tried what I assume is the
correct power cable and it continued to smoke.

You fried the modem and possibly the power supply. I would toss both in
the trash before you damage anything else.