USB powered Blu-ray drive - power supply issues

[Eug]

So, I bought a Blu-ray reader DVD writer off eBay a while back. It came with a USB cable and a USB to power adapter cable. It's a Pioneer BD-ROM BDC-TS02 slot-load drive in a generic USB 2 enclosure.

Plugged into two USB ports on my Acer desktop, it works fine.

Plugged into two USB ports on the same side of my Acer laptop it usually works fine, but not always.

USB -> power cable plugged into a cheap 500 mA AC -> USB adapter, the drive is totally flaky. (This AC -> USB adapter won't charge my iPhone 4, but will charge other USB devices.)

USB -> power cable plugged into a cheap 1 amp AC -> USB adapter, the drive is still flaky. (This AC -> USB adapter will charge my iPhone 4.)

USB -> power cable plugged into an Apple 1 amp AC -> USB adapter, the drive consistently works fine.

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Unfortunately, the drive itself says nothing about its power requirements. I'm just assuming it's 5V 1A, given the lack of its reliability running off my laptop's USB ports alone, and given the results with AC -> USB power adapters. It only works consistently with my Apple adapter, and not the cheap eBay adapters (not even the one that claims to be 1 A).

I have a bunch of 5 V 2.5 A AC adapters in my closet for old wireless access points. Can I just use one of those? I don't specifically need to get a 5 V 1 A adapter do I?

 

[corkyg]

Laptop USB ports do not always have sufficient power, especially when on battery. When I attach an external drive and Y cable to my laptop, one part of the Y goes to a powered USB 4 port hub, and the other to the laptop. Never a problem that way.

 

[Eug]

Can I just use a 5V 2.5A adapter? USB is 5V, and I assume the over-spec of up to 2.5A is not an issue, and the drive will simply take what it needs, nowhere near 2.5A.

 

[fralexandr]

Can I just use a 5V 2.5A adapter? USB is 5V, and I assume the over-spec of up to 2.5A is not an issue, and the drive will simply take what it needs, nowhere near 2.5A.

yep sounds like that should work, it won't draw more Amps than it needs

 

[corkyg]

Sure . . . as long as the connector fits correctly.

 

[Eug]

Thx. Works great with the 2.5 a adapter.

 

[Modelworks]

The problem you are seeing is likely due to the cheap adapters having a dirty output. I would get rid of the cheap adapters because they may harm your other devices in the long term. 5V @ 500ma is enough to run any USB device so if something says it is that rating and it isn't working, then the rating is either wrong on the adapter or the adapter is putting out dirty power. VERY common with cheap chinese supplies. I even found some that still have a connection to the 120VAC wall output on the output leads !

 

[Eug]

The problem you are seeing is likely due to the cheap adapters having a dirty output.

Yeah, given my results, I figured as much. It's amazing that Apple's super tiny adapter does so much better than the cheap chinese adapters that are 6 times the size.

BTW, in what way is the power dirty? Lots of fluctuation?

I would get rid of the cheap adapters because they may harm your other devices in the long term.

I was thinking of doing exactly that. Well, I'm keeping one because I'm using it to power some $10 speakers, so I don't care if the speakers die.

5V @ 500ma is enough to run any USB device so if something says it is that rating and it isn't working, then the rating is either wrong on the adapter or the adapter is putting out dirty power.

That should be true, but it isn't. It's quite common for USB drives to require more than 2.5 W. That's why you see those USB drives out there with two USB plugs, connected to the same USB port. One is for data and power, and the other is for additional power.

Apple has a different approach. Their external SuperDrive requires more than 2.5W too, but their solution was to overspec their USB ports on some of their portables so they put out way more power.

I even found some that still have a connection to the 120VAC wall output on the output leads !

??? How does that work?

 

[bruceb]

Power from a bad AC adapter can be bad either by output voltage fluctuations, current fluctuations or just bad filtering, resulting in a not very clean DC voltage out of it. It can be bad design, failing filter caps in the adapter or not enough caps in the filter. One bad rectifier diode can also cause issues. Most adapters use 2 for full wave rectification or a 4 diode bridge to do it. Either way, they are not working correct and should be junked.

 

[Eug]

So, with the AC adapter, I've not a problem with the drive since. At first I thought the drive problems were related to it just being a cheap eBay POS, but since sorting out the power issue, it's worked like a champ.

Mind you, I prefer to use my desktop drives anyway because they're faster both at reading and writing. I use this slim drive mainly when I want portability... which isn't very often these days for an optical drive.