maemo.org - Talk - Soldering advice needed for re-attaching N900 USB to mainboard.

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- - Soldering advice needed for re-attaching N900 USB to mainboard. (https://talk.maemo.org/showthread.php?t=54762)

Re: Soldering advice needed for re-attaching N900 USB to mainboard.

That could be it, since they only have I "F" item from the list.

I am just a bit worry because from the looks of it (in picture)... it look the same as those other brown capacitors (I will make sure they are not diodes in the next few days). And no SMD fuses from ebay look remotely the same as those brown cap component..

From Wiki, SMD capacitors looks like that in the picture. But as you said the marking is not right.

Could anyone with a n900 confirm opened this?

Re: Soldering advice needed for re-attaching N900 USB to mainboard.

Quote:

Originally Posted by fuji_man (Post 1136922)

That could be it, since they only have I "F" item from the list.

That symbol on schematics is definitely a fuse - at least during my school years that was the meaning of the symbol here in Czech Republic.

Edheldil

Re: Soldering advice needed for re-attaching N900 USB to mainboard.

thanks for the info... I have look up the symbol and it is correct that it is a fuse.. However I have no luck getting any 5v 2.0a SMD fuse.. Anyone know where to get one?

Re: Soldering advice needed for re-attaching N900 USB to mainboard.

If all else fails, You can always get bigger one and solder it with small cables voodoo... There should be enough place in case (maybe with a help of sandpaper'ing) to put somewhere even cylindrical big one.

// Estel

Re: Soldering advice needed for re-attaching N900 USB to mainboard.

I'd be willing to bet you can use a low end wire-based one and just tape/coat the wires to prevent shorting. If this were a data line, I'd be worried about propagation delays, but for a +5V line, it doesn't seem that important. The ones from Radio Shack or the like that I've seen in the 2A range aren't much larger than most SM components.

Re: Soldering advice needed for re-attaching N900 USB to mainboard.

its just fuse.. you can forget about it if you think that your charging supply will not do anything stupid.. its fuse, so the end on witch your should solder the wire are the same as another side of the same fuse, you what you can do is to solder your wire to a new location called N5300, but i dont know on witch side of N5300 you can.

and you than put your FUSE an wire itself, so thats how you can still have a fuse on your n900 :)

i find 2 additional spots for +5V. just look at photos.

btw, i have n900 with broken USB port to.. so just planning to buy new port and solder everything by myself with shaking hands :D

and for everyone, im not suggesting using glues, cause if somehow it will broke up again, you will have a big headache to remove them..

Re: Soldering advice needed for re-attaching N900 USB to mainboard.

Hi All!

I have the usual problem with the microUSB and I've read this thread front-to-back. I tried re-soldering it back and tried soldering a new one but to no avail.
Long story short: is there anyone here from the UK that could take the device in for the repair? Alternatively, I would need some detailed instructions because it seems I'm doing something wrong.

I've tortured the original microUSB till 2 pins fell off and the interior plastic got charred. Bought a new micro USB and tried the cables method. All went well up until I had to solder the base (shielding) to the mainboard. Firstly, couldn't get the MB pads tinned. When I succeeded I couldn't re-melt the tin blobs again. Seems to me my iron is too weak (15W) and the heat just escapes through the copper of the mainboard.
I still have the D+, D- and Batt+ pads intact (so there's still hope). Also my phone boots up and works properly (once assebled back).
Now, if some soldering guru that got his phone fixed could answer the following questions I might still give another try to re-soldering the USB myself.
1. How did you remove the metal shield that restricts access to the microUSB pins? Even if you unsolder part of it, there's no way to get behind it - between two adjacent shields.
2. What soldering iron did you use? Brand and power. (as mentioned, I've tried a 15W Toolcraft with needle tip but it's still too damn fat to fit between USB and shielding and too damn cold (I guess) to solder surface-mounted contacts).
3. What tip did the soldering iron have? I've seen someone here showing a jig made out of wire that he got around his usual soldering iron tip. I tried something similar (by holding a regular sewing needle attached to the iron tip) but the heat transfer was awful.
4. As a far fetched alternative, I'm also thinking of buying a used n900, hopefully with a damaged screen. Since I can't back up the phone the usual way, might it be possible to unsolder it's internal MMC and swap it into another phone?

Re: Soldering advice needed for re-attaching N900 USB to mainboard.

it's possible that Your soldering iron is too weak, but You could use a liquid, that allows solder to *much* more easily "grip" to copper surface. I would not try to solder N900 without something like that.

/Estel

Re: Soldering advice needed for re-attaching N900 USB to mainboard.

Quote:

Originally Posted by gebeleysis (Post 1197446)

Hi All!

1. How did you remove the metal shield that restricts access to the microUSB pins? Even if you unsolder part of it, there's no way to get behind it - between two adjacent shields.

I used a small side-cutter, it looked pretty bad after that.

2. What soldering iron did you use? Brand and power. (as mentioned, I've tried a 15W Toolcraft with needle tip but it's still too damn fat to fit between USB and shielding and too damn cold (I guess) to solder surface-mounted contacts).

(mostly unknown brand) 50W with adjustable temperature.

3. What tip did the soldering iron have? I've seen someone here showing a jig made out of wire that he got around his usual soldering iron tip. I tried something similar (by holding a regular sewing needle attached to the iron tip) but the heat transfer was awful.

A friend of mine grinded a regular to a smaller tip. But there are special ones for SMD.

4. As a far fetched alternative, I'm also thinking of buying a used n900, hopefully with a damaged screen. Since I can't back up the phone the usual way, might it be possible to unsolder it's internal MMC and swap it into another phone?

4. sounds good :) I spent many hours trying to repair the usb socket. The only thing I got to work was temporary connect an usb cable directly to the pads, because I had to do a reflash. IMHO repairing the micro usb socket only makes sense if you still have the intact pads on your board.
After my first n900, which I failed to repair (I used a wall wart charger + second battery for a long time), didn't boot anymore, I bought a "new" one with a broken display from an online auction. Because the display from my first one was OK, I replaced it with the broken display from the second one. And there I was: A full functional N900!! :cool:
I also hoped to swap the internal memory, but failed, it's soldered on pads _under_ the chip.. whatever.

and it's worth to make backups with the backup function of the device on a small microsd card.. ;)

good luck! :)

Re: Soldering advice needed for re-attaching N900 USB to mainboard.

Quote:

Originally Posted by Estel (Post 1197526)

Hi Estel,
What liquid do you mean? If it's flux then I did use a rosin-based flux and some other stuff, looks like a hand cream or some paste (got it from Clas Ohlson, had everything written in swedish on it so have no idea what kind of flux it is).

Edit: Estel, I've just noticed that you're the one that posted the mugen cover mod tutorial here. You mentioned there that you've used a very thin gas-powered soldering iron. Could you please give the brand & model or drop a link to it on ebay/amazon or other?