wired electric question! help pls!

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dorin · #1 Post by **dorin** » Mon May 29, 2006 6:00 pm

hi guys,

i got today an external dvd writer,LaCie dvd+/- slim, tiny and very light, perfect option to not carry anymore the big docking station for my x40 (my first thinkpad so i just ordered it last year fully optioned).

now comes the wired stuff: it has an power adaptor(lets ignore it!) and optional usb power cable and the normal usb data cable. till now ok. the funny think is that it functions with no pb without the usb power cable, so only with the data usb cable!!!

my question is: shall i use the power usb cable as well, or its enough to use the data usb cable wich seems to give it enough power to operate??!!

and like other i got stucked with a 50 dvds memorex+r pack which seems to be impossible to write multisessions on them (with traxdata no pb), any idea how to fix this? a firmware update or so? on nec (the drive inside is nec) it says the firmware update should no be used for external devices!

thanks alot!

dorin

christopher_wolf · #2 Post by **christopher_wolf** » Mon May 29, 2006 6:21 pm

I would go ahead and use the power cable that came with it as well; drawing too much power from the USB ports can be a bad idea and lead to some serious issues, serious as in needing a new mobo.

turbolium · #3 Post by **turbolium** » Mon May 29, 2006 8:32 pm

i think you only need the extra power if your laptop can not provide one since usbs usually cary enough power to power most of the devices.

i ran 2 external hardrive on t42 with out any problems copying/writing simultaniously and they do use as much power imo as a dvd writer would use

The only time you might need it if you have laptop wich does not give enough power to usbs (probably some cheper brand laptops)

christopher_wolf · #4 Post by **christopher_wolf** » Mon May 29, 2006 8:40 pm

It has been noted that some devices, if they draw too much power from a T4X Series Thinkpad's USB ports too quickly, can fry the USB connectors. If you can afford to have the USB power cable, I would err on the side of caution; better safe than sorry when it comes to the system board.

#5 Post by **GomJabbar** » Mon May 29, 2006 8:42 pm

christopher_wolf wrote:...better safe than sorry when it comes to the system board.

That would be my philosophy.

dorin · #6 Post by **dorin** » Tue May 30, 2006 1:14 am

thanks guys!

concidering the mainboard is the cheapest item in any laptop and for sure it will be covered under warranty guess i'll stick with one more cable, its not like have to cary the power outlet!

any ideas about how to be able to make multisessions on the 50 memorex dvd which i can't? (nero 7082)

once again,

thanks!

#7 Post by **GomJabbar** » Tue May 30, 2006 5:56 am

dorin wrote:concidering the mainboard is the cheapest item in any laptop

Huh?

I just looked up the price for the mainboard on my T42 and it's $750 from a couple of sites that sell IBM retail parts.

ACS Parts & THINKPADMEDIC +

Buy it now price on E-Bay is $525 for a working pull.

christopher_wolf · #8 Post by **christopher_wolf** » Tue May 30, 2006 10:01 am

GomJabbar wrote:
dorin wrote:concidering the mainboard is the cheapest item in any laptop
Huh?

I just looked up the price for the mainboard on my T42 and it's $750 from a couple of sites that sell IBM retail parts.

ACS Parts & THINKPADMEDIC +

Buy it now price on E-Bay is $525 for a working pull.

Dorin probably meant to say "*not* the cheapest item in any laptop"

dorin · #9 Post by **dorin** » Tue May 30, 2006 2:19 pm

yeap, i was sarcastic!

i meant of course i will use the extra cable rather than having to pay around 700 us for a new mb

#10 Post by **bill bolton** » Tue May 30, 2006 8:39 pm

christopher_wolf wrote:It has been noted that some devices, if they draw too much power from a T4X Series Thinkpad's USB ports too quickly, can fry the USB connectors.

This appears to be primarily an issue with devices which simply "draw power" for charging purposes, rather than devices which do a proper USB port negotiation over data and power needs.

A device such as an external DVD, which must do a proper USB negotiation as it needs to exchange data, is unlikely to do any damage to a USB port. At worst it may not work reliably if it cannot get enough power form the USB port, rather than damaging the port.

Some older USB port implementations were unable to to supply the 500mA and 5V rating of current USB 2 ports. As USB device vendor suppliers cannot know what USB ports a user will attempt to apply their device to, they play safe and provide "double up" USB connectors (etc.), but in reality these are not needed with contemporary laptops, such as the T4x range.

Cheers,

Bill

christopher_wolf · #11 Post by **christopher_wolf** » Tue May 30, 2006 9:15 pm

So that means that there is no built-in current limiter as per the USB 2.0 spec? If so, that would either leave the mobo mfg to put one in (95% out of courtesy; that idea will go over like a lead ballon) or leave the ports as they are.

I think you are right about something like a DVD or HDD not getting enough power and simply not working; i.e. they won't generate a huge load all of a sudden across the 5V for the USB.

dorin · #12 Post by **dorin** » Wed May 31, 2006 12:44 am

[censored] it!

i wish i'd have seen this before ordering the usb power cable set to allow me to use the small usb port, from the left side, the one under the normal usb port.

so you say its is more than safe (both for laptop and dvd bruner) to use only the data usb cable?

on the power ac adaptor it is written 5V 2.5A!

dorin

wired electric question! help pls!

wired electric question! help pls!

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