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Poll: Have you had charging or USB problems with your N900
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Have you had charging or USB problems with your N900

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abill_uk is offline abill_uk
2011-03-31 , 15:39
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#2081
Originally Posted by RWFarley View Post
I've had a feeling for some time that there was a software issue that exaserbates a hardware weakness. I need to plug/unplug multiple times to get charging to start.

Charging often "fails" overnight when there is no physical jostling. 2ce this week I've gone to sleep with the "charging pulse" light, only to awaken to a dead battery. (implies software issue)

My USB plug is firm, but brushing the cable will usually cause a disconnect/connect on my PC. (implies hardware issue)
Your usb problem is due to a hairline break on the charge pin of the usb connector and can be put right easy but you have to open up and solder down the pin, if you go to that length then it is worthwhile to do the job properly and scrape away the paintwork around the usb socket, solder both sides of it down to the earthplane and then solder all the pins at the rear... job done and you will not get any further problems with the usb port as long as you put enough solder to the usb earth plate/board.
 
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Texrat is offline Texrat
2011-03-31 , 15:53
Posts: 11,700 | Thanked: 10,045 times | Joined on Jun 2006 @ North Texas, USA
#2082
For those new to this, I was the first to report the problem (on my blog site: http://tabulacrypticum.wordpress.com...-an-n900-risk/) and as a former Nokia engineer responsible for internet tablets as well as former printed circuit card designer (for TI) I have some relevant background.

I am on my third N900 after having 2 micro USB connectors break (one after an accidental cord yank, one with no abnormal issues at all). I was able to keep my last broken N900 and was hoping to repair it myself.

I recently disassembled the broken N900 (not hard at all) to first examine the situation. What I discovered was disappointing.

The female micro USB connector is "secured" to the PCB with two soldered tabs and some adhesive. In earlier reports I mentioned copper coming loose from the PCB but that does not appear to be the case; it looks like I mistook the adhered portions for soldered.

What is happening is that the adhered portions ARE tearing free (too easily IMO) and the soldered tabs are also coming loose. Here's my revised assessment:
  • The adhered portion is probably ONLY to secure the component in place for wave or flow soldering. That's common.
  • The soldered tabs are the only thing truly holding these in place on the PCB. Examining the pads on the PCB shows no damage whatsoever. That is unusual: on a good solder joint, the solder should be tearing as it fails. Rather, this is coming loose cleanly-- which tells me that the micro USB connectors are not properly tinned. Tinning prepares the surface of a metal for proper soldering and is highly important.
  • Some charging issues are very likely the result of one solder pad coming loose first. The connector pins on the micro USB connectors are very tiny and fragile. It will take VERY LITTLE side-to-side motion to break one or more free. So intermittant charging issues could very likely be resulting from a single pad failure.
I will post pictures and this text on my blog as well.
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Last edited by Texrat; 2011-03-31 at 16:02.
 

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Texrat is offline Texrat
2011-03-31 , 15:54
Posts: 11,700 | Thanked: 10,045 times | Joined on Jun 2006 @ North Texas, USA
#2083
Originally Posted by abill_uk View Post
Your usb problem is due to a hairline break on the charge pin of the usb connector and can be put right easy but you have to open up and solder down the pin, if you go to that length then it is worthwhile to do the job properly and scrape away the paintwork around the usb socket, solder both sides of it down to the earthplane and then solder all the pins at the rear... job done and you will not get any further problems with the usb port as long as you put enough solder to the usb earth plate/board.
True, but the pins are VERY tiny. Most will lack the tools and/or skill for this.
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abill_uk is offline abill_uk
2011-03-31 , 16:07
Banned | Posts: 3,412 | Thanked: 1,043 times | Joined on Feb 2010
#2084
Originally Posted by Texrat View Post
True, but the pins are VERY tiny. Most will lack the tools and/or skill for this.
Problem is Texrat it has to be done as you well know, incidently did you notice just how small the pad is on the earth jacket to the pcb? if you look closely you will see the pads do not make contact with the main earthplain on the pcb, what i did to get a proper fix was to scrape off the paint on the main earthplain and join the tiny pads to the main earthplain, this makes the hold complete so it will not rip off the board no more as long as you use enough solder and also you can join this to the earth jacket very close to the usb socket making an even bigger fix.

Well done on your blog by the way, you really have done a lot of work even with Nokia on this one !.
 
Vasikaran is offline Vasikaran
2011-03-31 , 16:11
Posts: 65 | Thanked: 5 times | Joined on Jan 2011
#2085
I'm now bit afraid of this problem where the posts are flooding day by day...planning for a change of model soon before it breaks...to be on safer side..this USB port is really very important for charging in particular....without which the Phone is completely useless But worried about loosing such a great model in my life...no other go.. !!
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Texrat is offline Texrat
2011-03-31 , 16:13
Posts: 11,700 | Thanked: 10,045 times | Joined on Jun 2006 @ North Texas, USA
#2086
Originally Posted by abill_uk View Post
Problem is Texrat it has to be done as you well know, incidently did you notice just how small the pad is on the earth jacket to the pcb? if you look closely you will see the pads do not make contact with the main earthplain on the pcb, what i did to get a proper fix was to scrape off the paint on the main earthplain and join the tiny pads to the main earthplain, this makes the hold complete so it will not rip off the board no more as long as you use enough solder and also you can join this to the earth jacket very close to the usb socket making an even bigger fix.

Well done on your blog by the way, you really have done a lot of work even with Nokia on this one !.
I have not yet looked close enough. But I have a large magnifying glass with lighting that should help me get a better view. Right now I don't have a soldering tip fine enough to do repair work.

Thanks for the acknowledgment. I'm unhappy though that the work was one-way: other than initial denials that there was a problem, Nokia has been silent on the subject. They didn't even bother correcting my errors in the original assessment...

Latest poll results show 20% field failure rate. Completely unacceptable, Nokia.
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abill_uk is offline abill_uk
2011-03-31 , 16:22
Banned | Posts: 3,412 | Thanked: 1,043 times | Joined on Feb 2010
#2087
Originally Posted by Texrat View Post
I have not yet looked close enough. But I have a large magnifying glass with lighting that should help me get a better view. Right now I don't have a soldering tip fine enough to do repair work.

Thanks for the acknowledgment. I'm unhappy though that the work was one-way: other than initial denials that there was a problem, Nokia has been silent on the subject. They didn't even bother correcting my errors in the original assessment...

Latest poll results show 20% field failure rate. Completely unacceptable, Nokia.
Please do look Texrat and you will see the pads are not connected to the main earthplain at all, it is astonishing how they have designed it like this and the very reason the usb rips off the board.

You i know have been working with this fault from day one so i very know the amount of work you have done about this fault with Nokia direct.

I know the pins are tiny and requires a very tiny filed down if need be tip just to solder these pins at the rear but as you know i have repaired many now and i can honestly say not one has ever gone wrong since.

Secret is the earth jacket being soldered to the main earth plain by scraping the paint away.

I have done 4 completly ripped off ports so far and i had to link wire the rear pins to the nearest points on the board to recconect the usb but it is VERY possible and proves the N900 is repairable even in the worst scenarios.
 
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Texrat is offline Texrat
2011-03-31 , 16:26
Posts: 11,700 | Thanked: 10,045 times | Joined on Jun 2006 @ North Texas, USA
#2088
Originally Posted by abill_uk View Post
I have done 4 completly ripped off ports so far and i had to link wire the rear pins to the nearest points on the board to recconect the usb but it is VERY possible and proves the N900 is repairable even in the worst scenarios.
Have you posted repair instructions with parts, photos, etc? That would be extremely helpful. Or maybe even advertise your services to the community for a fee?
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abill_uk is offline abill_uk
2011-03-31 , 16:36
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#2089
Originally Posted by Texrat View Post
Have you posted repair instructions with parts, photos, etc? That would be extremely helpful. Or maybe even advertise your services to the community for a fee?
I will have to wait untill the next one comes in for repair, i did post some pics on here but not a complete fix with pics.

I hope the next one that comes in has been ripped off the board because it takes the tiny tracks off with them with little hope to join back that is why i link wire them using fine gauge wire to the nearest points.

IF the N900 is brought for repair BEFORE it ripps off ie when charging becomes erratic or becomes even slighty loose, the repair takes about 30 mins to complete from start to putting it back together as you only need to scrape the paint away to solder down the earth jacket and re-solder the data pins on the rear.

If your handed the device with the usb out altogether then it is about 45 mins work and i can tell you not one N900 is un-repairable, they all go back one way or another and never return for the usb fault.

This should give at least hope to everyone that has got the dreaded usb problem.
 
slcp is offline slcp
2011-03-31 , 16:53
Posts: 25 | Thanked: 2 times | Joined on Dec 2009
#2090
This is what I thought, though I was hoping they might be turning a blind eye as far as USB repairs go as it is an acknowledged design flaw...

I only removed the shield yesterday as well ( replacing the keyboard bezel would have be no issue...
 
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bad design, broken, charging, failure, hardware, loose, microusb, microusb port, n900, nokia, part, port, repair, return, surface mount, usb, usb port, warranty

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