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Posts: 77 | Thanked: 53 times | Joined on Dec 2007 @ Chester, CA
#1
So, i was fiddling around with my lipo/5v ubec charger and a usb hub so i could charge more than one device off the usb female plug i wired to the 5v ubec (voltage regulator), and i think i may have destroyed the charging electronics inside my n900.

What happened was i plugged a 2.5mm barrel plug connected to a 14.8v lipo pack directly into the hub's 5v input port, which might have pushed ~15-16v directly to the usb +/- pins, but the nook/hub is fine so that's kind of strange.

There was no indication of anything going south, and the nook color i had plugged in at the same time is fine, charges fine, but my n900 has not charged through the usb port sense. The hub works fine as well. I disassembled the n900 and the usb plug is physically undamaged, so a broken port can be ruled out.

So now whenever i plug my n900 into any usb device nothing happens. Wont connect via mass storage, wont charge off any charger i throw at it, tried 3 different cables, and the watt-meter between my ubec 5v regulator and the lipo pack shows no power is flowing. It works fine with my nook, as do all the usb cables.

Is there any software diagnostic applications available that can shed some light on this? IE if the usb port detects any thing is attached? Be it a charger, or a mass storage connection to the pc?

Its not a big deal, i use a usb 3.0 card reader for faster transfer speeds than usb 2.0, as well as to save my n900's usb port from breaking, and have a wall charger for my 3 bl-5j's.

i just would like to be able to charge it with the lipo/5v ubec regulator i have, on the go if necessary, IE not near an ac outlet. I have an external usb powered battery charger, but that is a bit cumbersome compared to being able to just connect a usb cable from my n900's m-usb to the female usb port on the ubec device.

Any ideas?

Thanks-

Last edited by eleseur; 2013-05-03 at 01:55.
 
Posts: 77 | Thanked: 53 times | Joined on Dec 2007 @ Chester, CA
#2
lshal -m turns up nothing as well, tried it with a wall charger, my ubec/lipo usb charger, and connected to my pc. Nothing comes up under any of those conditions.

I'll keep digging for info regarding the battery/usb software/hardware for the n900, but this is beginning to look not good at all.

EDIT-

Also just found this-

http://dmidv.de/articles/11/thanks-f...-fix-your-n900

Appareltly the author hooked up a 12v source to the usb input on his n900, and it blew an internal fuse protecting the device from such over-voltage/current conditions. He had the same symptoms i do and was able to fix it with a wire brige to short the blown fuse, and eventually replace the fuse.

Perhaps ill tear it apart again and test that fuse with a multimeter short test to see if blew. Hopefully thats the only thing i damaged here.

2nd edit-


So the fuse is shot, i'd do more testing, and try and short it then charge, but its late here. I'll update tomorrow evening when i have some time to tear it down again and see what heppens when the blown fuse is shorted/try to charge the device.

Fingers crossed

Last edited by eleseur; 2013-05-03 at 04:19.
 

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#3
I wish you luck! Fix that N900!

Idk what i'll do if I were to break my last 100% functional N900...
 
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Posts: 5,028 | Thanked: 8,613 times | Joined on Mar 2011
#4
Thee is huge probability of burnt-out 5V 2A SMD fuse. Check schematics to find it, it's rather easily reachable. You may also want to contact dr_frost_dk, he had same problem in the past and fixed it.

Of course, before any solder work, check that fuse with a multimeter, maybe it's not it.

/Estel
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Posts: 77 | Thanked: 53 times | Joined on Dec 2007 @ Chester, CA
#5
Thanks!

I hope its as simple as a blown fuse, but if not, i got a hell of a deal on a like new n900 on ebay ($145 shipped) . And i always have my n810 to charge batterys with soo its all good.

Definately going to take it slow, i know from expirence soldering/repairing small smd components on a mb is a delicate process.

I don't have a heat gun, but have seen soldering iron mods using a needle/thin copper wire tinned and attached to the tip to do precision work.

I'll keep yall updated/take pics in regards to the repair, as it may be of use to someone else down the road someday.
 

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#6
Please inform us about the issue. what did you do? could you fix it?
If yes, how?
because I have same problem here
I have connected VCC and GND vise-versa (while I was soldering the microusb connector)
 
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