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

The connection from pin1 (rightmost in this pic) to pin2 which is ID signal, i.e. the red line next to GND label, is incorrect. Pin2 should NOT get connected hard to GND. Though it doesn't do too much of a harm, it might cause conflicts with future versions of e.g h-e-n hostmode-pkg

Rationale: ID (pin2) is meant to detect insertion of A type plugs into (usually) AB-micro-receptacles. It signals to device to act as a USB host. It doesn't work OOTB on N900, but future H-E-N might actually look at it.

/j

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

http://talk.maemo.org/showthread.php...96#post1026196 and prev related posts. Thinking about the same, thought of a battery mod to have the pads on "outer" side so pogo pins can attach thru small holes in back cover, place the protective gear somewhere where battery plastic allows to mill out some volume, and place some mini spring loaded contacts on "bottom side" of battery

/j

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

There has also been a power-mat mod done to charge using the under-side pins in a wireless way. Similar approach without the need for physical alignment or external contacts.

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

Where can I buy a bottom mount micro usb port. Because on Ebay only top mount I found. From Mouser the shipping is too expensive. The port is £1 and shipping is £30.

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

Hi, just look for "nokia usb socket" or "micro usb socket". Those for other models also fit. I can confirm, that this one from ebay: "Buchse NOKIA 6500 8600 6555 8800 7900 Micro USB Connect (300505065513)" for various other phones fits.

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

Thanks. After a little more research on eBay I found this. It says for N900 and is cheap.

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

Hey! I wonder if you can help me find the right connector, I can't find it anywhere :( I really want to fix my n900

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

You can try the link in the above post. I bought a few of those and the seller says that are compatible with N900

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

I managed to repair my faulty USB port today. Many thanks to everyone to posted pictures to this thread, it was of immense help.

I apologize for lack of photos; I found myself reaching for my N900 several times to take some shots, then realised it was in bits in front of me :P

My port was still attached, but had dry solder joins on one or more of the 5 pins connecting to the pcb. (this means the solder has snapped and the legs are not bonded to the board, they are just touching it [occasionally, in my case].)

This symptoms of this are:
- Phone charges but only if you turn it upside down
- Phone charges but only if you fiddle with the usb cable till it's "just right"
-Phone charges when you hold the usb connector in the socket (and possibly gently push)

I found it got progressively worse to the point that I would spend 5 minutes every night making small adjustments to the cord and phone until it would start charging.

I pulled the device apart according to Nokia_N900_RX-51_Service_Manual_Service_Level_1_2.pdf (google for it).

I stuck a small piece of paper over the camera lense to prevent dust getting in, and removed the RF shield from the chip immediately next to the usb connector. The little clips on the side just click off with a small flat blade screwdriver. I then got some small side cutters and cut a very small section out of the RF shield rail (what the RF shield clicks down on) to gain access to the back of the USB connector. This should expose the surface mount solder points.

I then wound a pin around the end of my soldering iron, tinned it on and chopped the end off the pin off (it was too fine). From there I managed to heat up each contact till the solder re-flowed (I didnt apply new solder at all). Its very difficult to see exactly what you are doing with bare eyes - you cant tell if the solder has remelted. I experimenting with various lengths of time holding the tip onto the joins. Between each attempt I connected the screen and held a battery on the back of the board, to fire the device up and test for any improvement to the usb connector. I found that the best approach is applying the tip from a 45 degree angle, to clear the RF shield bracket and have a degree of visibility to the pins.

Once I had it reliably charging, I scraped away 1mm of green enamel on either side of the connector where the sides are soldered down, and applied a nice amount of solder to each side to lock it into position forever. Its imporant to not heat the connector up too much else the internal plastic parts will melt, but enough so that the solder "flows" onto the connector and onto he board where the enamel has been scraped off. Also take note of where the board fits into the plastic shell, there is a screw right next to one side of it; too much solder on the board will mean the board wont sit correctly on that mountpoint.

Hope this helps someone.. attached are some shots of my makeshift SMD soldering iron mod.

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

Could somebody post again the picture ?
Thank you.

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

got only this one. I'll look at home later, maybe I've got more. need them, too. I'm heading for a new trial :)

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

Just remember, that one thing was marked wrongly on this photo - ID pin shouldn't be soldered together with ground. It will work, but You'll loose possibility of detecting ID pin state with *may* be used in future by some package, H-E-N for example.

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

anyone still got the picture of the golden pads under the battery? of course with description.

edit: ah it's back online :)

http://talk.maemo.org/showthread.php...818#post997818


edit2: I've made a diagram for myself, to see how I have to connect my socket. the pink lines will be my wires from the usb socket to the pads. maybe it's useful for someone else:

edit3: Today I've soldered it like on the picture. Problem is not solved, but now, if I plug in the device on a computer or on the charger, it shows up the USB-symbol and asks for the connection mode (mass storage or PC suite).
I think I've made something wrong with the GND connection, because it came to my mind later, someone mentioned here, that GND is not USB-GND!

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

See my post:
http://talk.maemo.org/showpost.php?p...7&postcount=13

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

doesn't matter.
usb data lines are LVD* type so GND noise is rejected.
but BGND** != GND because between is placed a resistor for current sensing, used by BQ27200 chip

* LVD low voltage differential
** BGND battery ground

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

I have a different issue with the usb port and wanted to see if you guys could help..

One of the chip is gone from the board near the usb.. and I don't know what it is and the value of it.

Could someone give me that info and maybe even tell me where to get a new chip

See photo

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

So.. it is not a resistor afterall but a SMD ceramic capacitor.. On the schematic it is F5300 marked with a value of 2.0A, but what is that mean? What SMD capacitor I needed?

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

I personally would have guessed it to be a diode, but your schematic is showing it as a capacitor? 2.0A makes sense for a diode, being the amperage it can handle at 5v before it blows. A capacitor would be listed in Farads (or micro/pico Farads in this case).

Are you sure it's not a diode? Diode would make a lot more sense given it's location.

An example replacement would be something like this. That one comes in 8 or 12mm (though I'm sure you can find something similar in the proper packaging/spacing with minor searching on other sites).

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

Hey Woody, thanks for the reply

I don't know... I was reading that it maybe a ceramic capacitor, but I am not really sure..

The symbol on the schematic don't make sense.. I have attached the part of the schematic I am looking at...

It is the one circle (squared) in red.. it said F5300 (the position code on the board) and 2.0A...

http://catsitting.com/temp/1.jpg

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

It doesn't really make sense. A capacitor would look like the others in the diagram (C5301, for example), but you'd think it if were a diode it would look like the one shown near it (N5300). Are you sure these are position codes? It seems awfully convenient that all the things labeled with a C are capacitors... I'm thinking it may be more a part reference list.

In any case, the only thing I can think of that would list amperage would be a diode. Capacitors would be in Farads (27pico, 100nano?). If these aren't location codes, maybe the F stands for fuse? Do they make ceramic SMT fuses?

Turns out they do. Here's a 2.0A at 24V. Just find a 2.0A at 5V and I'll be that's your candidate. That could also explain it "evacuating" the board when overloaded?

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.
 

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.
 

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.
 

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?

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

@gebeleysis
to be honest I have no idea - my gas-powered soldering iron is no name :p It's much more important to use thin tip - as for "heating base", everything that doesn't blow gas container into Your face is ok.

As for tips, I also can't be much of a help, as I've done them myself - using cooper, most of the times. unfortunately, it may be quite hard to create soldering tips on Your own, if You don't have appropriate tools.

In such case, You should determine type of soldering iron You want to buy, by it's extensibility and availability of replacement tips and their types.

Anyway, here is photo of my soldering tips collection + soldering iron, for reference:
http://lorienart.pl/soldering-iron.jpg

/Estel

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

Good golly! how did you go into the slim n900 with a monster like that?? :)
Just kidding. Good thing you could do it! I guess this hints that a higher power soldering iron is in order.
Thanks.

Offtopic: how do I PM you? have questions about the Mugen cover mods.

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

Noticed just now that you've answered all my questions in the quote. *sigh* I guess I have to make up the courage and try again with a higher power soldering iron.
Another question:
5. where did you get the cables for the connection? That's assuming you used the cable method, not just re-soldering to the pads. I guess something out of a dead pair of headphones could work but am not sure.

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

You should be able to PM me by clicking on my nick and selecting appropriate option - I don't have any blocks. If it isn't available, maybe Your post/thanks count and/or time since registering is too small - I don't remember thresholds here.

As for tips, You need a smallest possible to attach cable to usb port (pins are damn small), but quite big (and, preferably, flat a the end) one to heat up testpads enough.

As for cables, You may try with headphones one, but most likely, it's going to turn being too *thick* ;) Also, remember about twisted-pair (see wikipedia) - to preserve noise-free high-speed USB, You should twist Data+ and Data- together (no need for doing it with mass and 5V, in fact, it would be counter-productive).

BTW, You only need to "fight" with three small pins on USB port - Data+, Data- and 5V. Mass can be soldered together with USB port shield (creating big soldering point - of course, You sill need to connect it to appropriate testpad), and 5th pin can be left alone or soldered with mass - it's purpose is to inform device about hostmode cable being attached, but N900 Hostmode doesn't use it, and it's most unlikely that it's ever going to start doing so.

/Estel

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

Thanks, Estel and Lazart for your tips.
I see now that there are things I should have done differently. I'll have to buy another soldering iron and give it another try.
I hope the phone can take some more punishment :D

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

This seems like what I need to do to my wife's N900. For over a year she's been using an external battery charger and she's constantly changing batteries. Of course she didn't bother to tell me that the USB cable wasn't charging while it was still in warranty. Anyway I want to get her N900s USB port working properly. I disassembled it yesterday and this is what it looks like:
http://img818.imageshack.us/img818/4...usbsocket2.jpg
Is this what yours was like? It seems like the method you described would apply to my problem. Reading your post made me hopeful that I might be able to fix this without too much trouble.
I read about using Kapton Tape on adjacent components to reduce the risk of damage due to inadvertent heat transfer. Also I thought I might just get a sacrificial soldering tip and sand/grind it to a fine tip to do what you did. It seems like there may be enough solder already there to just re-flow each contact if I keep a steady hand. I'm guessing the less I mess with it the better.
And It'd probably be a good idea to also reinforce the solder at the mounts, as you did, while I'm in there. I read a whole thread that strongly advises to reinforce the USB mount as a precaution to a known weakness of the N900.

I had to put hers back together as is, now I'm trying to research the best way to fix it and what stuff I need to get to do it.

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

TheJason,
Quick advice: use a powerful enough soldering iron (this was my first mistake) because a weak iron will just have all it's heat sucked out without being able to melt the solder on the joints.
Another advice: you will have to cut part of the shielding away. If you use a tip that's thin enough to fit between the port and the shielding it will probably be to thin to properly heat the joints anyway - not enough heat transfer.

Estel, Lazart and others who've successfully done this. I need help. Re-soldered the port today, but it acts wierd.
Symptoms:
- when plugged into the PC the screen lights up, but the mass storage vs pc suite mode dialog doesn't come up.
- when plugging a wall charger in - it starts charging but disconnects by itself in 1-2 minutes. Then, without any interference, starts charging again, and so on. In about 10-15 minutes it disconnects/reconnects each 2-3 seconds.
- tested the connections with a tester: first plugged a USB cable (for ease of access) and it shows me that the 3 pins that count each connects to only one pin at the other end - no bridging. The two data pins have no contact with the cable shielding (ground) and the +5v has about 10 ohms resistance towards ground. Also there's direct contact between two leftmost pins and base (see picture http://i1032.photobucket.com/albums/...-overview2.jpg).
I'm very frustrated. I'm afraid that some components might have been damaged by heat during the operation. Has anybody encountered this? Any ideas why this might happen?

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

I certainly have no idea, but if anyone wonders how someone could be reluctant to do their own soldering -- this thread gives an idea.

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

TheJason,
One more thing: cover the camera with Kapton tape. Or, even better, remove it completely. The trick is to get two very thin things on two opposing sides of the camera. I used a shaving blade (old style) broken in halves. Once the locks are disabled this way, the camera is easily removed, say with a small screwdriver, by leveraging it over the receptacle margin. Although the Service Manual says the same camera module should not be re-used after removal, I believe this isn't because the camera becomes ruined after removal. Moreover, I can testify that the camera & camera port are very robustly made (for such size), more robustly that this f*****g microUSB port.

geneven,
I'm not sure I know what you mean :)

As for my previous post, one small detail: when I had just soldered the port bak, I tried starting the disassembled phone and connecting it to the PC - it worked amazingly well. Didn't work that well after I assembled it (this might invalidate my assumption that I fried something up, as I didn't heat the phone after that).

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

I know this is old but maybe this helps. I would Imagine (I am supposing here) that your data pins are soldered to close together and somehow interfere or that one of your data is soldered to close to the voltage or ground:
Nokia chargers shortcut the data+ and data- pins so it knows it is a charger. Maybe if it does not show i with your computer its because those pins are shorting themselves. Something similar could be happening when plugging into the charger, it might be shorting with one of the data ports and hence disconnects.

I want to believe that your data- is touching/shorting the ground (or voltage- in some places) and hence it messes up. Give it a look and come back with anything :)