MIDI sync drop when powered by USB

[spajk]

My recently purchased keystep completely drops out when powered by USB.

I switched to using a phone charger to power the device and the problem seems to have gone away.

I power other musical devices via USB, including my MIDI interface and they don't drop out.

I would like to get to the bottom of this to save myself a wall socket.

What I know:

-Power saving is disable on the OS and all USB ports.
-chipset and other drivers up to date
-I have tried all USB ports and a high quality, powered hub
-lots more things I can't think of

I know it sounds like insufficient power to USB problem, but like I say, this doesnt happen to  more demanding devices

Could there be any options in the arturia software that might aleviate this? or any other troubleshooting tips? thanks

EDIT: Forgot to mention this is a desktop PC running windows 10 64 bit, with a a high quality PSU with more than enough power.

Intel 5820K
Asus x99-a
16GB DDR4

[megamarkd]

"Phone-charger" power adaptors tend to provide a rather high amp draw.  As it works fine with one of those, it sounds like you computer isn't providing the 500mA required by the Keystep.
Make sure you are using a USB port on your computer that is able to output a constant 500mA.  Some USB ports, such as ones on the front of cases, can be actual two USB socket headers plugged into a single USB port header on the motherboard so will be slitting the power available to it when both (or sometimes, all 4) sockets are being used.  Another issue is the USB port you are using simply isn't able to provide more than 250mA, for whatever reason the manufacturer has decided.  Try it on a different USB port.

[spajk]

"Phone-charger" power adaptors tend to provide a rather high amp draw.  As it works fine with one of those, it sounds like you computer isn't providing the 500mA required by the Keystep.
Make sure you are using a USB port on your computer that is able to output a constant 500mA.  Some USB ports, such as ones on the front of cases, can be actual two USB socket headers plugged into a single USB port header on the motherboard so will be slitting the power available to it when both (or sometimes, all 4) sockets are being used.  Another issue is the USB port you are using simply isn't able to provide more than 250mA, for whatever reason the manufacturer has decided.  Try it on a different USB port.

Thanks for your reply, Mark. Looks like I might have to go back to the drawing board to make sure my USB ports are supplying enough power. I bought an expensive, powered hub especially for this problem, which should be supplying enough amps, also tried every USB port off the motherboard. Might have to dig a bit deeper.. thanks

edit: just checked my HUB specs (plugable USB 10 port) 2.5 amps available and I'm certain I am not drawing all of that.

[megamarkd]

Does the hub have a power supply for it or does it draw it's power exclusively from the computer?  Check the maximum amp out put of an individual port on the hub also.  Even though the total amps it can output is 2.5 amps, often they won't output more than a particular level through each port.  For example, I have a powered USB hub with a power switch I use with my MIO4.  It has 10 ports and is rated at 5v/3amp but can only send up to 1amp to any port and won't sent the full 3amps to any one port.  And if I have a device sucking that 1amp it'll only have 2amps available to send around to the other ports.  So if I have another device pulling 1amp, again I'll be left with the difference available for the 8 other ports, and so on....
USB hub makers are out to make money and generally won't point any of this out to you.  I went through a few hubs that didn't output a regulated amperage before I got the one I did, including a powered 8 way hub that was essentially a 4 way hub if you wanted to connect devices with anything over 250mA to it.

[spajk]

it's not bus powered. Well, it can be but I'm using external power.  It looks like it supplies up 5 x 500ma (out of a total of 2.5amp ), i've only got 4 devices on it. Very strange. you mention 3amp draws, but I always though the max of one device could only be 500ma, unless I am missing something.

https://plugable.com/products/usb2-hub10s/ this is the device. It does state "Not a standalone charger, NOT FOR CHARGING iPad or devices requiring more than USB’s standard 500mA" but going from your first post they keystep doesn't need over that. It seems strange even my motherboard ports can't power it either..

I will just buy a power adapter to save the headache but it's bugging me why I can't supply it enough power