t42 usb port issues

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psteven · #1 Post by **psteven** » Thu May 11, 2006 3:46 am

I have a t42 2373-jtu . Am having intermittent connections on my usb ports when its connected to an external drive or thru my pocket pc thru activesync . My usb mouse is not somehow affected, is this hardware related or is this a motherboard issue, have upgraded all my software thru the ibm software installer. The unit has two years warranty left

#2 Post by **GomJabbar** » Thu May 11, 2006 6:24 am

Just be careful that you do not plug in a USB device that draws too much power. A few users here have fried their USB ports that way.

cmarti · #3 Post by **cmarti** » Thu May 11, 2006 11:36 am

What kind of error if any it gives?

psteven · #4 Post by **psteven** » Thu May 11, 2006 4:48 pm

no errors actually , connection just gets cut off from time to time

#5 Post by **bill bolton** » Thu May 11, 2006 5:47 pm

psteven wrote:My usb mouse is not somehow affected, is this hardware related or is this a motherboard issue

USB ports start out in a low power mode (~100mA of current available) and switch to a higher power mode (up to ~500mA current available) on negotiation with the connected USB device. A mouse is a low current device and will run fine in low current mode, with no need for negotiation, but a drive needs more power and will attempt to negotiate a higher current mode.

Since your mouse is OK but a drive isn't, you may well have a problem with the power negotiation function on your USB port . This is usually a hardware level problem.

Cheers,

Bill

cmarti · #6 Post by **cmarti** » Thu May 11, 2006 9:05 pm

My suggestion. Try not to use anymore the drive in your usb ports, it could get worst and then you will need to buy another mobo.

davidspalding · #7 Post by **davidspalding** » Sat May 13, 2006 10:08 am

When the USB items are connected, take a look at the Device Manager (DEVMGMT.MSC). Under the USB hub devices, the Power tab will indicate what is connected and what power it's drawing.

Me, I'm a fan of powered USB hubs that you plug mice, drives, web cams (notorious power suckers), etc., so the laptop's USB port is operating simply and at low power ... let the $20 (varies) USB hub do the heavy lifting.

[edit]P.S. You might be getting early indications of a USB port failure, which is usually a planar replacement. Your -JTU ought to still be under warranty, so I'd keep regular backups and keep an eye on this ... with the notion of a warranty fix BEFORE yours expires.

wantathinkpad · #8 Post by **wantathinkpad** » Mon May 15, 2006 4:17 pm

GomJabbar wrote:Just be careful that you do not plug in a USB device that draws too much power. A few users here have fried their USB ports that way.

I think I just did that on my T43. But it was with a digital camera usb? I don't understand. How do you know if a device is hogging too much power.

pae77 · #9 Post by **pae77** » Tue May 16, 2006 11:45 am

I've got a related question. The mini dock which I use has 4 USB ports and its own power brick which is bigger than the standard AC power supply for the laptop. My understanding is that the power supply is bigger because the USB ports on the mini dock are powered. So my question is would it be safe to plug a power hungry USB device (like an external USB drive that draws its power from the USB port) into the USB ports on the mini dock? Or, would I be better off connecting a separate powered USB hub to one of the ports in the mini dock and connecting the external drive to the hub?

davidspalding · #10 Post by **davidspalding** » Tue May 16, 2006 11:51 am

wantathinkpad wrote:I think I just did that on my T43. But it was with a digital camera usb? I don't understand. How do you know if a device is hogging too much power.

Well, for one, it probably won't work. For another, I believe the power tab has some info indicating insufficient power for device. Did you see that?

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