On Sun, Dec 5, 2010 at 4:02 AM, Clark Martin <[email protected]> wrote:
>
> On Dec 4, 2010, at 11:50 PM, Stephen Conrad wrote:
>
> The folks as The Apple Store on the Country Club Plaza (Kansas City, MO)
>> said I'd be fine using a 6V DC power cord on my USB 4-Port Hub that says it
>> needs a 5V DC power cord (they said it would only draw 5V DC). I asked them
>> as the only Universal AC Adaptor I could find has 3, 4.5, 6, 7.5, 9 and 12V
>> settings (Voltage Selector).
>> Were they right or do I need to order a cord from Belkin?
>>
>
> First go back to the store and tell them they are quite wrong.
>
-> I spoke to the Genius Bar folks on the phone. Apple's own Tech Support
folks agreed with these guys.
>
> General rules of power supplies in particular, wall warts.
>
> 1 Polarity is most important, get it wrong and BAD things happen faster
> than you can see.
>
> -> I got this right, made sure to do that. It is a + 5V tip
> 2 Voltage needs to be right.
> In some cases it can be higher or lower than spec'ed but only if you
> know what you are doing.
> Otherwise it should be as spec'ed. Devices don't "draw" voltage,
> they get what you give them.
>
> 3 Current needs to be at least what is required but can be more.
> Caveat to this rule is that many power supplies are expected to be
> loaded down by a certain amount of current.
> That is the output voltage drops as the load (current) increases.
> This is factored into the design.
> So if you use a power supply that has a significantly higher current
> rating that the device it may well supply
> too much voltage.
>
-> Should I drop it to 4.5 then?
>
> 4 The connector needs to match. This is last because if it doesn't match
> nothing happens.
>
-> When I switched it from Bus-Powered to Self-Powered it worked fine
>
> The typical power supply for a USB hub is a regulated supply. This means
> that whether it has no load on it or it's maximum load the output voltage is
> regulated to within a few percent of 5V. Your typical universal wall wart
> isn't regulated so it's voltage could be several volts above or below 5V.
>
> An unregulated 6 volt wall wart, especially one rated for 2.5 amps is
> likely to put out about 8 volts with just the hub connected. But even if
> it's spot on at 6 volts you run the risk of blowing the hub and everything
> plugged into it.
>
> You may be able to find a suitable replacement power supply as all 4 port
> USB powered hubs I've checked use a 5V power supply rated at 2.1 to 2.5A.
> But do watch out for polarity and the connector.
>
-> How do I know the Amps? Nowhere in the paperwork of on the card does it
say anything about this.
>
> You are probably better off just going out and buying a new hub. The
> latest hubs I've bought were Belkin 4 port at the local Target store for
> $15-$20. IF Belkin will sell you a new power supply it may run nearly that
> much to buy it, including shipping and handling. If you buy a replacement
> locally then you can still use your old one as a bus powered hub (for light
> loads only.
-> If only I had a target closer than Kansas City (45 miles roughly).
Walmart USED to sell lots of computer stuff but after the remodel that
section was pretty much gutted.
>
>
> --
Steve Conrad
Henrietta, MO 64036
"The time has come for mankind to grow up and leave its cradle behind; to go
forth and claim our place in outer space."
- Capt. Henry Gloval
(\__/)
(='.'=)
(")_(")
Help Bunny Take Over The World!
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