Can't recognize DVD with 10 feet USB cable

**msun** · 12-29-2007, 09:00 PM

I have a external DVD-ROM looks exactly like this:
http://www.centrix-intl.com/details.asp?productid=1918

However I'm having trouble only if the enclosure is connected through a 10 feet USB extension cable, tried 3 cables but the same thing. If I measure the USB port on the back of PC I got 5.08v, with 10 feet cable it measured 5.07v so it doesn't looks like I have voltage loss issue. But the DVD won't power up and get recognized correctly, DVD would make a clicking sound and CD eject button won't even function, and I have already provided an extra 5V power to the enclosure. When connected directly to PC everything works fine, even without the extra 5V.

What could be wrong? I'm thinking maybe amperage loss but I can't figure out how to measure it...

**2k1Toaster** · 12-29-2007, 09:59 PM

nope. You have data loss. You would need to get an active cable, or just place it closer.

**msun** · 12-30-2007, 04:48 AM

Thanks for the suggestion, I ran to Fry's and got two more USB extension cables, and

1. 10 feet USB extension cable, $8
works for DVD, USB stick but not 2.5" HD

2. 16 feet active cable, $20
works for all.

Both works much better than my original $0.99 10 feet cable

**loginfailed** · 12-30-2007, 07:09 AM

That problem can also sometimes be due to a lack of power to operate the USB CDROM over longer USB cable runs. The little wires inside a USB cable are very thin and the longer distances can cause a drop in available voltage and current by the time the cable makes it from one end of the cable to the other.

I have a 16ft active USB cable and still had those same problems using a Pioneer DVD-R unit like this one:
http://store.mo-co-so.com/external-u...rive-p-36.html

I ended up using a spare mini itx power supply to provide the DVD-R with its own dedicated 5 volt source and its been working good since then.

I found some decent 120 watt mini itx power supplies $18.99:
http://store.mo-co-so.com/120-watt-1...pply-p-49.html

I used the 12 volt rail to run my screen and the 5 volt rail to run the DVD-R. This way, the power supply is right there in the front where my screen and DVD-R are located so distance for the power cables isnt so long.

You have to do a little wiring to get the power supplies to work without a switch or motherboard attached. But people who have a CarPC installed should know what to do.

I used a spare USB port on my PC. Took an old USB cable and cut it off and then hooked the power leads inside the usb cable to a 5 volt SPDT relay that sends 12 volts to the mini itx power supply. That way it powers up at the same time as the rest of the USB stuff with no user intervention required.

I dont work there for MCS, so dont think Im trying to promote that store or anything by posing 2 links to there. Its just they had some decent prices for stuff that I needed.

**sta1N** · 12-31-2007, 04:14 PM

You'll need something like this
http://cgi.ebay.co.uk/USB2-USB-2-5M-...QQcmdZViewItem

It's a 5m USB Cable with a repeater. Cable looses signal after 3 meters. It's not just the voltage that you need, but the data info sent from main source to your DVD Player.

Hope that helped