Dell Latitude d400 USB power problem

[ratdude747]

great. my dell latitude d400 rear usb port crapped out on me.

I recently bought a new mainboard for it... the old one had the 855 usb data failure, and i bought a used mainboard for it.

the warranty expired 4 weeks ago and now i have a problem. the rear usb port is not getting power. it gets data just fine.

any advice? I removed the mainboard and the soldering APPEARS good... but the usb joint is covered in yellow flux-like crap so i do not have the best view.

This laptop gets used a lot and one usb port down is not good. I do not have the funds for a new laptop so i have to make this work... I love it otherwise, but this is driving me nuts.

[seanc]

Re: Dell Latitude d400 USB power problem

Poke around the previous board and the current one to see if you can find the source of the problem?

[Scenic]

Re: Dell Latitude d400 USB power problem

or run a jumperwire from another 5V source directly to the USB port.. with a picofuse in series for protection

did that once when a USB port fuse burnt up so violently it FUBAR'd the traces. ran a jumperwire with a picofuse from the HDD power pins to the USB ports.. (on the motherboard connectors.. not soldering it to the HDD itself)

[ratdude747]

Re: Dell Latitude d400 USB power problem

or run a jumperwire from another 5V source directly to the USB port.. with a picofuse in series for protection

did that once when a USB port fuse burnt up so violently it FUBAR'd the traces. ran a jumperwire with a picofuse from the HDD power pins to the USB ports.. (on the motherboard connectors.. not soldering it to the HDD itself)

i would but the last time i tried extracting a picofuse off a dead mobo i burned it up... maybe i need to turn down the heat.

the hdd is on a daughterboard on my model... and the fan i is not always 5v.... so idk where to go. perhaps the alternate power for the dbay port (the good usb) would work.

[Scenic]

Re: Dell Latitude d400 USB power problem

i meant one of these.. not the surface mount type
http://i12.ebayimg.com/04/i/000/fb/6e/a04e_1.JPG

[yyonline]

Re: Dell Latitude d400 USB power problem

Don't ask me how, or why, b/c it makes no sense... but I once managed to fix this problem in a D800 by removing all the USB ports/hubs/controllers from Device Manger, rebooting, and letting it redetect them. It's worth a shot.

[ratdude747]

Re: Dell Latitude d400 USB power problem

tried it and it didn't work.

[ratdude747]

Re: Dell Latitude d400 USB power problem

i think i have it.

the dbay extension, used to gove ADDITIONAL poer to the lef usb port, is on the SAME plane as the right usb port's 5v pin.

thefrore, the plane has more then the usual load

i think i will run a jumper wire from the dbay 5v plane to the back usb 5v plane. i was able to do it on my old board without any major issues.

sound like plan?

[ratdude747]

Re: Dell Latitude d400 USB power problem

wow. that post hass too many typo's. what i meant to say:

i think i have it.

the dbay extension, used to gove ADDITIONAL power to the left usb port, is on the SAME plane as the right usb port's 5v pin.

therefore, the plane has more then the usual amount of juice.

i think i will run a jumper wire from the dbay 5v plane to the back usb 5v plane. i was able to do it on my old board without any major issues (physically, not able to power test it).

sound like a safe plan?

[ratdude747]

Re: Dell Latitude d400 USB power problem

anybody? i don't want to do it unless i have some input from the experts around here...

[Th3_uN1Qu3]

Re: Dell Latitude d400 USB power problem

Well, what would you want to hear? I'd go ahead and do it, BUT cut the old 5v trace to the USB port just to be sure.

[ratdude747]

Re: Dell Latitude d400 USB power problem

based on what i was seeing, i think all of the traces go to the same place.

trying it soon.

[Th3_uN1Qu3]

Re: Dell Latitude d400 USB power problem

Not necessarily. USB ports have overcurrent protection so at the very least each one will have a current sensing shunt.

[ratdude747]

Re: Dell Latitude d400 USB power problem

then why are 2 sources meant to be used to exeed usb power put on the same trace? i assume that means i can use just a jumper wire?

[Th3_uN1Qu3]

Re: Dell Latitude d400 USB power problem

then why are 2 sources meant to be used to exeed usb power put on the same trace?

I can't understand you, rephrase please.

[ratdude747]

Re: Dell Latitude d400 USB power problem

abothe the right port (working) there is an additional 5v boost connection for dell dvd drives. it and the port are on the same 5v trace. since the purpose of the 5v is to give additional power to the usb port, that means the trace can power more than 1 usb port.

[Th3_uN1Qu3]

Re: Dell Latitude d400 USB power problem

The shunt resistors may be there without you seeing them.

[ratdude747]

Re: Dell Latitude d400 USB power problem

uhh... the pins are literally on the exact same giant plane. as in a plane 1cm wide has 2 holes in the area, one for each pin. and it ain't ground either, which is similar but bigger (for the usb shell).

[ratdude747]

Re: Dell Latitude d400 USB power problem

all considered, I would like a final look over from an expert since my new freebie laptop was a bust and this is all i have to play with... if it is likely safe, i will go ahead and do it. if not, then i will not.

[ratdude747]

Re: Dell Latitude d400 USB power problem

bump