Heavy USB Problems

[Doc_T]

Hi all,

I have really bad USB problems and I don't know what to do. The situation is this:

I have an iMac, and I want to connect several things to it via USB, that is

– MT4 MIDI Interface
– Presonus AR16
– Arturia KeyLab 61MKII
– Roland TD25
– KORG Monologue
– KORG SV-1
– Vox Continental
– Keyboard
– Mouse

As you can see it is more devices than USB Ports available in my iMac. So I need to use a USB hub. I have a seven port wall powered Hub that works fine with all my gear except the KORG Keyboards.

When I connect any of the keyboards directly to one of the build in ports of the iMac they show up in the MIDI environment and everything works as expected. When I connect any of the keyboards via the USB hub their repective icons in the MIDI environment stay gray and the Computer does not connect to the keyboards. However, this behaviour is erratic, meaning sometimes it works and in the next moment it doesn't.

I have tried different orders of switching things on (iMac first, than the keyboards abd vice versa etc.), which I thought I had finally worked out, but right now nothing works anymore. They boards will not connect via the hub.

I have installed the latest KORG Driver (1.2.5) and previous versions, no luck.

Maybe I am missing something obvious and maybe (hopefully) there is an easy fix. Anyone?

Thanks for your time

[Doc_T]

Disconnecting the USB hub from its power supply and reconnecting it solved the problem (for now).