Power rating on X40 USB ports?

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taob · #1 Post by **taob** » Sat May 15, 2004 6:36 pm

Am I right to assume that only the USB port on the left side of the X40 is powered (ignoring the proprietary IBM power connector underneath it)? Does anyone know if it supplies only the minimum 100 mA of the USB 2.0 spec, or can it meet the 500 mA burst requirements of some devices?

csv96 · #2 Post by **csv96** » Sat May 15, 2004 7:48 pm

Both USB 2.0 ports are powered. Don't know the exact power rating but both ports power an external bus-powered USB 2.0 hard drive with no problems. The auxillary power port is just for the IBM USB 2.0 Multi-Burner.

taob · #3 Post by **taob** » Sat May 15, 2004 8:58 pm

Alright, thanks. I looked through the May 2004 Thinkpad PSR, and the exact wording is "Two USB (version 2.0), plus one powered USB port for select IBM options"... of course, that makes it sound like there are three USB ports in total on the X40.

I looked for the X40 HMM, but it only appears to be available in Japanese at the moment...

csv96 · #4 Post by **csv96** » Sun May 16, 2004 8:10 am

Here's the Hardware Maintenance Manual (in English):

http://www-306.ibm.com/pc/support/site. ... MIGR-53683

Even more confusing is that when you attach the X40 to the X4 Ultrabase, the left powered USB 2.0 port and the auxillary power port are inaccessible (part of the X4 blocks both ports), but you gain 3 additional powered USB 2.0 ports on the back of the X4 for a total of 4 powered USB 2.0 ports. All the rear X4 USB 2.0 ports also work fine with bus-powered hard drives.

taob · #5 Post by **taob** » Sun May 16, 2004 11:06 am

csv96,

Thanks for the link to the English HMM... I searched for both "X40" and "Thinkpad Hardware Maintenance Manual" on the IBM publications site, but neither turned up this document.

How does one locate documents like these (like if I wanted the T42p HMM)?

taob · #6 Post by **taob** » Sun May 16, 2004 11:08 am

Wait, I think I just answered my own question. The solution is not to use IBM's search page, but thinkpads.com's and look for posts from you.

http://www-307.ibm.com/pc/support/site. ... MIGR-46464

csv96 · #7 Post by **csv96** » Sun May 16, 2004 10:48 pm

You're welcome. The way I find the HMM is to go to IBM.com, click support, click online publications, and then select the model I'm looking for.

csv96 · #8 Post by **csv96** » Thu May 27, 2004 12:31 am

New Update (and a bit of a warning):

I have an IBM/Hitachi Travelstar 80gb 5400rpm drive mounted in an external bus-powered USB 2.0 enclosure. Lately I've been burning CD's at 24x speed from this external drive. It appears that the three expansion USB 2.0 ports on the X4 Ultrabase may be too underpowered to sustain constant data transfer from the bus-powered external drive. At least once or twice per burn, the drive will click loudly and then pause for several seconds. Occasionally there will even be a buffer underrun occurence.

However, if I plug the external hard drive directly into the native USB 2.0 port on the X40 itself, there are no problems. No pauses or clicking.

So it seems that the three expansion USB 2.0 ports on the X4 should probably only be used for keyboard, mouse, printer, card reader, etc.,

cynic · #9 Post by **cynic** » Thu May 27, 2004 4:52 am

taob wrote:Am I right to assume that only the USB port on the left side of the X40 is powered (ignoring the proprietary IBM power connector underneath it)? Does anyone know if it supplies only the minimum 100 mA of the USB 2.0 spec, or can it meet the 500 mA burst requirements of some devices?

All of the T40's ports meet the 500mA. I can't imagine IBM skimping out on the X40-- but I'll have one soon enough to check.

csv96 · #10 Post by **csv96** » Thu May 27, 2004 10:26 am

If the X4 acts as a hub, does that mean it's 500mA split 3 ways?

Power rating on X40 USB ports?

Power rating on X40 USB ports?

Re: Power rating on X40 USB ports?

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