thanks for the post and a quick one - the bezel aeound the keyboard in my n900 is kinda loose e.g it moves so is it the case of that teeth not fitted in its place?? thanks

an idea: do you have a noncritical micro usb plug that you can stand to potentially lose or replace? the only thing that will really fill the whole socket cleanly and be super easy to remove is the microusb plug itself. ideally you should be able to do this epoxy job without getting a drop inside the socket, but its there just in case. Even if you were to get some inside the jack you would be able to easily remove it somewhere between epoxy set and epoxy cure and see evidence of epoxy on your plug, while you could still remediate if necessary. Easily worth potentially sacrificing a $3 generic microusb to USB-A cable rather than permanently buggering your jack

First of all, as I said in my original write-up, I am not just gluing the USB port to the lower PCB alone. That would not be strong enough. I am encapsulating the USB port in epoxy, and using the heatsink behind it, its own solder points, the upper PCB, the upper PCB plastic support, etc to strengthen its adhesion.

And I actually did the test you suggested. I took an old SODIMM stick that visually has a PCB almost identical to the N900 (the green mask is identical, same types of components spread around, etc). I applied blobs of epoxy at random over its entire surface.

Some epoxy blobs covered memory chips, others touched the solder mask and metallic connectors, yet others just sat on top of the solder mask with no contact to anything else.

After letting the epoxy cure for less than 1h, I tried removing one blob that was covering just the solder mask. It was purely sitting there, not touching any components, memory chips, traces or metallic components. I had to pry it off with a screw driver, applying so much force that I would have ripped off your solder job and the USB port with it.

Yes, I know epoxy is not ideal under these circumstances. But I'm willing to bet money that properly epoxying the USB port will be just as strong if not stronger than resoldering two contacts. And I did not point this out before, but you only really strengthened one side, the other is just as weak as before. To get to the other side, you would have to take the upper PCB off, which I think is impossible without ruining the sticky foam and who knows what else.

Lastly, this is the epoxy I used: PermaPoxy General Purpose Epoxy Feel free to test it yourselves before disassembling your N900s. Just make sure you follow the instructions on the back of the packaging regarding mixing, etc.

Update: It is now about 12h of curing, and the epoxy strength is identical to that after 1h of curing. But draw your own conclusions guys...

I don't argue with epoxy it's your business how deal with.
at beginning epoxy is sticky but in a few weeks epoxy become more rigid and prone to detachment.
for both solutions, even epoxy have infinite strength, final strength uf usb port is provided by adherence of copper layer to epoxyed fiberglass substrate

for those who want use epoxy : try to get stretch foil . thickness is only 23 microns
http://www.dapas-konice.cz/images/stretch.gif
put it over plug and insert into usb socket. doing like that you protect contacts and put a polypropylene layer between epoxy and plug. epoxy don't adhere to polypropylene

Allright guys, this will be my last update to this thread. The how-to will stay up indefinitely (until Google decides I've taken too much bandwidth). I did my absolute best to come up with a method that will improve the USB port strength without endangering the N900 internals.

I even verified that the Epoxy I used is safe for electronics, that it doesn't shrink (I even called Permatex and they confirmed it) and that, while far from perfect, it does stick to PCBs. Now only time will tell. But I will say that I've used Epoxy in a variety of circumstances, and it held up far, far better than any other adhesive I've ever used.

Good luck with any of the fixes you chose to implement.

not my experience - I've got some heavy use items (metal to plastic) with epoxy fixes applied that hold up well > 3 years.

I did follow your advice to scrape the green off of the main board

I cleaned the port and board with acetone before applying the epoxy

I'm confident in the fix - thanks for the pics & writeup cr0c0

Ok after saying it was going to do this over a month ago I finally got around to it.

From my side I scraped the solder mask on the right side of the usb port away so that I could run a bead of solder along the side of the usb port. Secret here is to use a blade on the soldermask and very gently scrape away - rather use 100 light scrapes and slowly remove the mask then doing it on one or two scrapes and risk removing the coper layer. The left side of the usb port was too inaccessable to try get a soldering tip in without risking melting the ribon cable going up to the board above the usb port.

I then decided to add epoxy too - on the left of the usb port and aboveit. I used JB Quick since it sets nice and fast. To prevent any epoxy from going into the usb port I get a existing usb cable and sprayed some WD40 onto it and put this into the socket. The idea here is that if any epoxy does get through the gaps in the usb port, the epoxy will not stick to the plug because of the wd40. I left the plug in for about 4 minutes (jb weld was nearly set by then).

Phone is reassembled and working 100% - hopefully this will give me piece of mind when plugging it into the charger. As someone who bought my phone from an importer in Australia I doubt I have a warranty anyway.

I can see that both the points are soldered, is there no short circuit??

Thank you..

no . both points are part of the receptacle metal body soldered to ground.

hi
i have one question :/
if mi usb port has fall off, can i fix it ?
:S