# USB device does not wake up after sleep



## G9A9O9 (Jan 21, 2010)

HI

I wonder if anyone can solve this one:

I have several *USB sound adaptors*, which cost just a few dollars on eBay, and plug into your USB port to provide additional sound out paths on a Mac.

These devices are tiny USB plugs that actually contain a digital-to-analogue sound card converter, and have a microphone jack (3.5 mm) for audio input, and a headphone jack for audio output. Even the USB sound adaptors that are designed for PC work fine on the Mac, and without any driver. And as I say, you can pick them up for just a few dollars.

I find these USB sound adaptors useful. I have three of them, and I can connect various pieces of audio equipment to each of these USB sound adaptors (such as my headphones, my hi-fi, my multimedia speakers, etc), and then conveniently switch the Mac's Sound Out to the required USB sound adaptor, just using the Sound Control panel. 

This means that I don't have to start plugging my headphones, hi-fi, and multimedia speakers in and out when I want to use them: I just change the desired output via the Mac sSound Control panel  (or even more conveniently, via the freeware "SoundSource" menubar sounds source changer).

This all works very well.

However, quite often when my MiniMac wakes up from sleep, one or more of my plugged in USB sound adaptors will become effectively unmounted, and no longer responds. Of course, pulling the USB device out and plugging it back in again fixes the problem, but I would like to know why they do not wake up from sleep, and become inactive or unmounted. I also have a USB hard drive plugged in, and this has no problems with waking up after sleep.

One solution is perhaps finding some software, or an Applescript, that remounts all USB devices after my machine wakes up from sleep. Does anyone know of such a utility?

But I will be grateful for any other suggestion as to why this is happening, and on how to fix the problem.

Many thanks for your assistance with this.


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## MisterMe (Jan 21, 2010)

You have a simple problem. It is not necessary to tell your life's story to explain it. Short stories are sweet stories and are more likely to be read to completion and to elicit a helpful response.

That said, I presume that your adapters are bus-powered. That is, they draw a finite amount of power from the USB ports. My guess is that the Mac shuts down the USB ports and thus unmount devices that draw power like your adapters. I also guess that your adapters have no way to remount themselves when your Mac reawakens.

These are my best guesses about the cause of your problem. The fix? Well, if I am correct, then there is no fix beyond what you are already doing. Remove and then reinsert each adapter after sleep.


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## ElDiabloConCaca (Jan 21, 2010)

What happens if you connect said audio devices through a powered USB hub?  It stands to reason that if the hub can correctly "wake from sleep," then the devices attached to said hub may also be able to correctly wake from a computer sleep state.


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## G9A9O9 (Jan 21, 2010)

That is a very good idea, eldiabloconcaca.

Perhaps it is just the loss of USB power that (presumably) occurs during sleep that is the cause of all the problems.

I will see if I can get a power supply form my USB hub; it does have a power in socket.

Thanks.


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## G9A9O9 (Jan 21, 2010)

Hi MisterMe: Apologies for the rambling story.

What I wrote was a bit of a mixture of a technical query; and a write-up, detailing to others this cheap way of getting extra audio in/out ports for the Mac. But I guess those details do not really belong in the tech support area.


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## ElDiabloConCaca (Jan 21, 2010)

Gotta agree, it was a bit rambling, but TOO MUCH information is always better than TOO LITTLE information.  Too little information doesn't get us anywhere, but too much doesn't hinder anything (other than getting to the point).

Let us know what the results of your testing are!


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## G9A9O9 (Feb 16, 2010)

No, it did not work: providing USB power continuously while the Mac sleeps did not solve the problem: the USB sound cards still remain "unmounted" after sleep, and I have to unplug them and re-insert to get them back. (Not all the time though, sometimes after sleep they do mount OK; I am not sure why this just happens sometimes).

Does anyone know if there is a simple software utility, or and Applescript, that can remount USB devices? Disk Utility can re-mount, but it only picks up hard drives and other storage media.


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