On Dec 5, 2010, at 5:55 AM, Stephen Conrad wrote: > 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.
"Card"? Do you mean the hub? The hub will require 2.1 to 2.5A. Each port needs to be able to supply .5 A and the hub itself needs some. > > 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. Office supply, something. Sorry, I live on the edge of Silicon Valley so finding a store that sells computer stuff isn't too hard. Clark Martin Redwood City, CA, USA Macintosh / Internet Consulting "I'm a designated driver on the Information Super Highway" -- You received this message because you are a member of G-Group, a group for those using G3, G4, and G5 desktop Macs - with a particular focus on Power Macs. The list FAQ is at http://lowendmac.com/lists/g-list.shtml and our netiquette guide is at http://www.lowendmac.com/lists/netiquette.shtml To post to this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/g3-5-list
