N900 partial disassembly and USB fix *UPDATED WITH GOOD PICTURES AND FULL WRITE-UP*
 

*UPDATED WITH FULL WRITE-UP AND GOOD PICTURES*

I decided to take apart my N900 in order to fix the USB port issue. As many of you know, this USB port is prone to breaking off on the N900, and after looking closely at the system board it's not surprising. It's surface mounted, with 4 very small solder points and two epoxy contact pads underneath (cannot verify the epoxy pads without breaking it off, at which point it's too late).

After fixing it yesterday, and verifying that it still works, I opened it again today to verify the epoxy adhesion and to take better pictures. I also did a full write-up on my site. At this point everything works as new, and there are absolutely no signs that my N900 was ever taken apart. For those of you that disassembled the N810, the process is virtually identical.

http://sites.google.com/site/svcr0c0/n900

Word of caution, be careful when applying the epoxy. There's more than enough space around the USB port, however the metal casing of the socket itself is full of holes. And epoxy tends to run and plug them up. If that happens you won't be able to insert the USB cable into the socket.

Re: N900 partial disassembly and USB fix
 

nice, I was thinking about this today but ran out of time.

Re: N900 partial disassembly and USB fix
 

Well done for being brave and doing this. Pity the pictures weren't great, but I know how hard it can be to take extreme close-ups.

Re: N900 partial disassembly and USB fix
 

I was tempted to take it apart again to get better pictures (manual focus with the Rebel, better lighting, etc), but the two Torx T6 screws bite into the plastic keyboard bezel, and I really doubt they'd stand another tightening.

If I can get a new bezel from somewhere, I'd gladly do it though. I think this fix actually works, and would save a lot of potentially broken N900s. Guaranteed to void the warranty, but I started without any warranty anyway.

Re: N900 partial disassembly and USB fix
 

Update: I took the N900 apart again and took much better pictures. The keypad bezel held up just fine, and the epoxy is rock solid. I'm absolutely sure this will fix the USB port issue for those of us who do not have Nokia warranty.

If you also file down the teeth on the micro USB charger and cable, then you're pretty much guaranteed never to have any issues.

Re: N900 partial disassembly and USB fix
 

Excellent, thanks for the clear pictures and text. It might be a good idea to link to this thread from http://talk.maemo.org/showthread.php?t=37107 in case people miss this thread.

Re: N900 partial disassembly and USB fix
 

I put silicon spray on my finger and after on the plug and now it's easy to charge with the usb cable

Re: N900 partial disassembly and USB fix
 

I didn't want to bump my own thread, but I'm amazed with how worried everybody is that their USB port will fall off, and yet nobody else tried doing anything even remotely like I did.

At least those with electronics experience, give an opinion if epoxying the port like I did will strengthen it, if the bond will last or if it's just a waste of time.

Or is everybody sitting on the fence, waiting for Nokia to replace every single N900 they ever sold?

Re: N900 partial disassembly and USB fix
 

IT might be worth adding one thing to your instructions. Before applying the epoxy wipe the usb connector and surrounding PCB area with an ear bud soaked in ethanol (alcohol) or acetone (nail polish remover). This will remove any flux that may still exist on the board from manufacture and ensure a better bond for the epoxy.

Cleaning boards with either these two solvents in 100% safe and standard practise in most, if not all, electronic refurbishment centres.


It might also be a good idea to try somehow cover the holes in the USB socket to ensure that epoxy does not get into it and prevent the plug from being inserted cleanly. I have been trying to think of a way to acomplish this. One ide is to use very small pieces of blue-tac (http://en.wikipedia.org/wiki/Blu-Tack) since if these get through to the internal connecter they should be harmless and probably come out with the plug next time it is removed.

I intend to do this mod to my N900 this weekend. As they say prevention is better than cure. :D

Re: N900 partial disassembly and USB fix
 

Many of us, especially with no experience in hardware modding have no courage to open their 500 euro phone just to make sure it doesn't break. I rather risk my USB port breaking and then returning it to nokia for repairs than void my warranty. Of course it is different in your case as you didn't have the warranty in the first place.

Re: N900 partial disassembly and USB fix
 

Nokia replaced my N900's weak USB port when it broke after a month. Then, I learned and I just filed down the charger's hooks as is mentioned elsewhere on this forum and I haven't had a problem since.

Some forum members were also passing around the authorized Nokia disassembly guide, so it's good to know an experienced person such as yourself has done this successfully. That means there is hope for my meat head and sausage fingers to fix mine should it ever break again.

Thanks!

Re: N900 partial disassembly and USB fix
 

Very good point, I actually hadn't thought of it. It should definitely help. I can't go back and redo mine, it's epoxied for good. :D

Alternatively gaffer tape or masking tape would work too. I opted not to bother, and just keep the epoxy mainly in the back of the USB port. Not that you don't have enough room to apply more of it. The way the n900 is designed, the system board has a LOT of room around it where the USB port is located.

Well, this fix only applies to working N900s. Once the USB port breaks, there's nothing you can do about it.

I understand completely, but I can't be the only one who bought his n900 on the grey market without warranty. And believe me, I was very nervous about taking apart my n900, especially after seeing those guys butcher it in the youtube clip, and having no other instructions to follow. :p

Then again, I have some experience repairing laptops, so that helped. The main rule to follow is that nothing should take a lot of force to take apart.

Re: N900 partial disassembly and USB fix
 

I have a DDP device so I'm without a warranty and thus extremely concerned about a possible future break of the USB port. I'm also an electronics engineer. Despite this, I'm very hesitant to dismantle my N900 so that I could epoxy the USB port. I did watch the original disassembly video that was posted on a gadget site a while back, but I simply don't feel comfortable with disassembling/re-assembling small devices like the N900. Give me an old TV any day though..

Re: N900 partial disassembly and USB fix
 

Can you please explain this a bit more;

You did this instead of using the epoxy; You did this without opening the phone;

Re: N900 partial disassembly and USB fix
 

can someone link to the 'filing down the usb cable hooks' details?

thanks

Re: N900 partial disassembly and USB fix
 

Re: N900 partial disassembly and USB fix
 

Why not use epoxy between the plastic cover around it and the usb port just for preventative measure?I was thinking about it the other day.This way it will held for longer.

Re: N900 partial disassembly and USB fix
 

Because unfortunately that is impossible. You have the case at the bottom, then the system board mounts upside-down into it, with the USB port, camera, etc facing into the plastic casing. You have to remove the system board from the casing in order to access the USB port and the empty space underneath.

Even if you considered filling up that space with epoxy, you need to be careful not to cover up the hole for the LCD screw, while building it up high enough to reach the USB port. And epoxy dries up extremely fast, becoming brittle if you try to remould it. But once it cures, usually within 24h, it can be sanded down as reshaped that way.

If someone can come up with a way to do it though, I'd like to hear it. :)

Re: N900 partial disassembly and USB fix
 

I actually had a thread on this a month or so ago, but the chief holdup for me was that I would void the warranty in the event that some other issue were to pop up. Now, if this machine makes it past the end of my warranty period (one year, U.S. -- as I understand it), then it is the first thing I will do. Probably that day. Watching the assembly, dis-assembly video shows that technically it is really not all that challenging. Glad to see you have done it, though. Gives me hope when the time comes.

Re: N900 partial disassembly and USB fix
 

My solution
i don't want to wait and i fix this in advance . put some epoxy between secondary board and usb socket have placebo efect because secondary board is fixed with dual face adhesive sponge .

Advice . protect camera lens when solder

Re: N900 partial disassembly and USB fix
 

In the first picture it looks like you filed down the PCB a bit. what is the grey material you uncovered? Please tell me it's aluminium, because then your fix may actually work better than mine.

Re: N900 partial disassembly and USB fix
 

SnPb solder alloy ( 63%-37%) melting point 183 oC :D
I filled around usb green solder mask to uncover copper layer and solder a little bit more :D

Re: N900 partial disassembly and USB fix
 

Yes, that is pretty much the solder I have as well.

But I was referring to the silver line that you created by filing down the green layer off the PCB. Is that entire line aluminum or copper? Or is that just the PCB material with the green paint removed?

I'm really tempted to resolder my N900 as well, but only if there's something more to solder to. If the only metal within the PCB is contained within the pads themselves, they'll just break off along with the extra solder.

That's why I didn't even try it in the first place, evne though I'd rather solder 10 things than epoxy one. :p

Edit: Oh, and I take exception to your calling my epoxy job a placebo. :D Seriously, from what I could tell, that upper PCB is sandwiched between the main PCB (system board) and the plastic casing of the phone. It's as solid as it'll get, as it's held tight by the LCD screws. :D

Re: N900 partial disassembly and USB fix
 

Great thread thanx for sharring !

I guess repairing a detached usb port is not impossible once the case open ...

Re: N900 partial disassembly and USB fix
 

what silver line ? i don't understand . edit the picture and mark it.
around pads is copper ground plane and pads are separated from this layer because this layer dissipate heat in solder process and final solder can become "cold" . in all designs ground pads obey this rule

Re: N900 partial disassembly and USB fix
 

http://www.pixhost.org/show/668/1649..._0366_edit.jpg

I used my Jedi Paint skills to highlight the area. What is that gray stuff? I keep asking these questions because I never filed down a PCB before, and I don't know how many layers there are.

Re: N900 partial disassembly and USB fix
 

Next time first search forum for link to service manual L1/L2 which has step-by-step instructions for disassembly and assembly.

Re: N900 partial disassembly and USB fix
 

this is copper ground plane exposed . this layer is painted with green solder mask ( i don't remember english industry term )
I scratched this layer until i reach copper layer to solder on it . n900 pcb is multilayer and signal traces are in the middle . exterior copper layers are mainly ground plane.
i think you don't deal with pcb

Re: N900 partial disassembly and USB fix
 

Hmmm,

That might be a better solution than epoxy - expose the ground layer next to the UCB plug and run a bead of solder onto it and then the plug.

Or alternatively if you still want to do the epoxy it would not hurt to take a nice sharp knife and scratch the ground plane below where you plan to put your epoxy - this provides for a nice mechanical grip for the epoxy to hold onto.

On the subject of epoxy I have also thought of a good way to ensure that any epoxy that might run into the plugs holes does effect the usb plug. Borrowing on what someone else posted about spraying silicon on your usb plug - do this and then carefully insert the usb plug into the socket before applying epoxy. Leave the plug in during the full epoxy drying time and then remove. The idea being that with silicon on it the plug will not adhere to any stray epoxy that might get through the holes, and, since no two bodies can occupy the same space in time, the plug provided a mold to ensure that any stray epoxy does not affect further insertion of the USB plug.

Re: N900 partial disassembly and USB fix
 

put me down for 'poxied

hardest part for me was reattaching the screen ribbon

glad you mentioned this. I ran most of the epoxy along the sides. It does want to enter those holes. I actually pulled and reinserted the usb plug during the dry time and it saved me some trouble. That said, it is possible to get inside the port with the smallest screwdriver to do SOME damage control after the fact if the epoxy enters the port.

Re: N900 partial disassembly and USB fix
 

Is it possible to use this kind of epoxy?

http://aetos.it.teithe.gr/~v13/n900/20100228_002.jpg

I'm unfamiliar with this, so I'm also attaching the directions it came with. The epoxy itself is in the case at the right side of the picture. It has the white substance at the center and the green substance around it. You mix it with your hands.

It is something that you mix with your hands and it is already somehow solid, so it should be easy not to go into the slots. However, I'm not sure whether it will stick or fit for that purpose.

Re: N900 partial disassembly and USB fix
 

guys stop using epoxy . is not appropriate for this purpose .
epoxy have weak adherence on pcb green paint . you can test it using an old computer board trying to stick something on it. the only way is solder alloy . epoxi can be used only on base wich is fiberglass epoxy ( under green layer on etchted zone ) but n900 pcb have copper on most of the surface

Re: N900 partial disassembly and USB fix
 

And one more question (even if it is a bit late). Is it ok to use superglue?

I've N900 open right now and have already put some superglue (carefully) at the
bottom, in order to glue the metal with the plastic.

Have I just destroyed N900?

Re: N900 partial disassembly and USB fix
 

you just did the worst thing
superglue vapor will condense on gold contacts
after a while the glue become brittle

Re: N900 partial disassembly and USB fix
 

I didn't understand 100% of what you said. You mean that the contacts will become worst, or that the glue will break at some time?

I only put instant glue at some points at the bottom, between the plastic and the USB connector.

Re: N900 partial disassembly and USB fix
 

yes , the glue will break at some time

the glue vapor (fumes ) can make glue deposits on contacts and guess what will be hapen... no good electrical contact between socket and plug . if this hapen you can remove superglue from contacts using acetone . be very careful with acetone . don't touch anything else than usb port
if you have problems with contacts avoid mechanical cleaning
you can remove gold from contacts wich thickness is only few microns

Re: N900 partial disassembly and USB fix
 

I used that solid epox. It seems to have glued well and is *very* easy to apply. Even if it didn't glue well, it doesn't allow the usb slot to move at all, so it should be ok.

As for the instant-glue part, the one thing that I thought a bit late is that I could have left the plug inside while applying it. That would stop fumes from going on the contacts (if they want anyway). The instant glue seemed to fit very well under the slot.

Here are some screenshots and an off-topic "wtf" thing.

Before:
http://aetos.it.teithe.gr/~v13/n900/SDC10608.JPG

After:
http://aetos.it.teithe.gr/~v13/n900/SDC10618.JPG
http://aetos.it.teithe.gr/~v13/n900/SDC10617.JPG

And the thing: What is this???
http://aetos.it.teithe.gr/~v13/n900/SDC10604.JPG

it seems to always face down but it can't be part of the accelerometer because it doesn't move smoothly. I'd guess that it is a device to determine where N900 faces (i.e. for snooze) , but AFAIK that is not described anywhere.

Re: N900 partial disassembly and USB fix
 

@v13: that's actually the vibrator

Re: N900 partial disassembly and USB fix
 

And why pray tell should anyone avoid toucing anythign else on the board with acetone? Every electronic refurbishment centre I have seen uses a acetone based solvent to clean PCB's. Being an organic based solvent I dont believe it reacts with metals in any way.

Re: N900 partial disassembly and USB fix
 

but plastics do
secondary board support is made of plastic, keboards . damages can happen