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

maemo.org - Talk (https://talk.maemo.org/index.php)

- Nokia N900 (https://talk.maemo.org/forumdisplay.php?f=44)

- - 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.

@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.

Quote:

Originally Posted by Estel (Post 1197830)

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.

Quote:

Originally Posted by lazart (Post 1197642)

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! :)

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.

Quote:

Originally Posted by jabawok (Post 1062790)

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.

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.

Quote:

Originally Posted by gebeleysis (Post 1201060)

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 :)