mac mini and usb devices

**planetg** · 09-17-2008, 10:11 AM

i'm running XP on a Mac Mini with the follow devices connected to the 4 USB ports
1. Emu 0202 External Sound
2. Touchscreen
3. Matrox DualHead2Go VGA splitter
4. USB mouse

When I plug out the USB mouse and try to power up a USB hub, it turns on. However, no devices are able to work within the hub, including the USB mouse. Am I short on power?

I'm currently using the P1900. Will adding a 5V supply solve my problem since I'm suspecting my USB bus is overloaded with the 3 devices mentioned.

Pls advice.

**Bugbyte** · 09-17-2008, 12:32 PM

That sounds like the problem. When you plug just one device into the hub, does it work? If so, try two. If that works, try three and so on.

Try them in different orders in case they draw a lot of power. If any of them work when plugged into the hub alone, that is most likely the problem.

**Machinehead** · 09-17-2008, 01:18 PM

If it is a power issue the 5v supply add-on will solve that problem.

**planetg** · 09-17-2008, 08:23 PM

nothing works in the hub.

when i plug out the hub and put a usb mouse instead, it works.

am i not getting enuff power? the hub works as expected on my macbookpro with no other usb devices

cheers

**Bugbyte** · 09-17-2008, 08:26 PM

Well...THERE's yer problem! Don't know why it is finicky but sounds like the hub.

**planetg** · 09-17-2008, 11:08 PM

does that means the additional 5v supply for my p1900 shd solve the issue?

another piece of advice i need. is it possible to split the 12v secondary voltage to 2 lcds?

else what's the best method to power up
1. mac mini
2. 7" lcd
3 10" lcd
4. 5v powered usb hub

is getting 2 p1900 the only way to go?

thanks

**Machinehead** · 09-18-2008, 06:47 AM

Test the hub with it plugged in to the wall. That will tell you if that's the problem.

You can power a second LCD off a cigarette lighter adapter rather than spend money on a second p1900. Radio Shack makes adapters you can hide behind the dash.

**golfguy** · 09-25-2008, 10:38 AM

You can just split the power from the P1900 to two screens. My calculations show that there's power left over after my mini and my screen. You'd have to find out how much power your USB hub needs to determine if you can power the second screen.

**planetg** · 09-26-2008, 02:52 AM

you mean splitting the secondary output to power 2 LCDs? Is that possible?

i'll be getting the 5V add on regulator for the usb hub

**golfguy** · 09-26-2008, 01:26 PM

Yes, it's possible. Check your screens for power dissipation specs. Carnetix says the secondary output is good for 15 watts or 1.3 amps at 12v. If your two screens use less than 15 watts, you will have no problem powering both of them from a single output. All Xenarc screens on their company site are specified at <8 Watts. Lilliputs are speced a little higher. These are peak power demands and not steady-state dissipation. The Carnetix manual states that the P1900 is protected from overcurrent by automatic shutdown and will not be damaged if you overload the 12v output. So you can try it without worrying about killing your power supply. If it works, you're good, if not, you can run one of them from the included 12v car adapter, except you won't get the auto power-off.