need advice on soldering on my n800!
 

Well I have a n800 with a broken usb jack. (and no way to get it repaired commercially) So I figured I would solder it back on. I have done SMD soldering before but I have never soldered on a multilayer PCB so I'm just wondering will it damage the PCB (more than just visually) to hand solder on it? And there is a battery nearby that worries me...

http://www.lookpic.com/files/129.JPG
http://www.lookpic.com/files/214.JPG
http://www.lookpic.com/files/311.JPG
http://www.lookpic.com/files/412.JPG

Re: need advice on soldering on my n800!
 

There shouldn't be any problems soldering connector back. Only danger I would see is that you overheat pads on PWB which could cause them to detach. Everything else is correctable with solder wick :)

Re: need advice on soldering on my n800!
 

:D Thanks! For archive sake I will post the results tomorrow

Re: need advice on soldering on my n800!
 

If you are nervous about doing it, I can do it for you. I do this sort of thing all the time.

It is good that you took excellent photos of the PCB, I can see there is no visible signs the board has any physical damage yet. Looks like your solder is just torn free.

The key to doing this is having the correct tools and the experience. You definitely do NOT want to use too much heat.

I'm not looking to make any money, just offering to help out a fellow member of this community. Let me know.

Regards,

M5

Note: The best tool to do this is a reflow, hot air tool on the data pins. It can be done with a 25-30 watt pencil soldering iron also, but that would be my second choice for doing the pins should you not have access to a hot air soldering tool. The four pads on the corners will need a soldering iron because the USB metal housing will suck heat away too quickly to use hot air. You'll want to remove the old solder on all the pads first, then tin the pads with fresh solder (preferably silver solder), then align the connector and reflow the solder that was put down during the tinning process. Do not overheat the substrate. Afterwards, wash the solder's flux away with a solvent and blow it dry with compressed air or nitrogen. If you used rosin fluxed solder (instead ofwater soluble flux), the common solvent choices are Toluene, Methanol or Chlorinated Brake Parts Cleaner. Use a disposable toothbrush on the area after wetting it with solvent. Immediately blow it dry before the solvent dries on it's own. Repeat the washing and compressed blow drying until the board area looks spotless.

From the looks of your pictures, the factory soldering on the four corners could have been better, which is why the connector broke free when pulled on. It is a common defect with SMT electronics when small parts and large metallic connectors are mixed on a substrate and passed through a tunnel furnace. The engineers fear a profile that is too hot, and error on the side of too cool, and you see this result. The real solution is to hand solder the four anchor corners AFTER the board exits the tunnel furnace but the extra step adds labor costs, and so it gets bypassed frequently.

This is a huge problem in the laptop computer industry where the power connector is attached to the motherboards. All the factories need to do is hand solder that section, but most of them don't and you get end-users with loose power connectors later on. It is a manufacturing defect that doesn't reveal itself until long after the product has left the factory. I have fixed close to a hundred of them.

If you do it yourself. I hope it works out. Regards.

Re: need advice on soldering on my n800!
 

Nice. Sounds like planned obsolescence.

Re: need advice on soldering on my n800!
 

CooCooCachoo.... actually the laptop manufacturers lose more than they gain because many laptop power connectors fail within the warranty period costing companies like HP/Compaq, Dell, Gateway big time.

I am not an Apple fan but I have to hand it to them in the manner they solved the problem. Apple notebooks have a connector that uses a magnet to hold a flat (rectangular) connector against a planar contact surface. If someone trips over the power wire, or the user forgets it is plugged in and carries the notebook away from a desk, the magnet just lets go of the power adapter's wire and there is no harm done. It is a smart solution. I'm sure if you ask Steve Jobs he will say it was his idea :-).

We all live in a yellow submarine.

Re: need advice on soldering on my n800!
 

Thank you all very much i'm going at it as soon as I eat dinner. I do have a reflow so I think I will be fine. Once again thanks! will post photos later

Re: need advice on soldering on my n800!
 

jchord,

Well ???

Re: need advice on soldering on my n800!
 

You know, I've been having all kinds of problems with my (warranty-expired) N800 having boot loops, so I finally took it apart using ThoughtFix's very helpful video/pix. It seemed to go pretty smoothly, but now I've lost any screen responsivity (although, oddly enough, the booting has actually improved!). I just examined it under magnification, inspecting the screen's plug and socket, and look what I found! You can see the one resistor (presumably) that is dangling at one location, and I think there are two other devices missing as well.
You know, I think that I actually MIGHT have the capability of soldering that loose item (I did once successfully UN-solder a resistor like that on a Mac Mini that I over-clocked), but I have no idea what to do about the missing ones. Maybe I could salvage some similar ones from some other circuitboard / broken cell phone. Any pundits know what's supposed to be there? ( I realize this might be a stretch...)
I'm in central Mexico, BTW (and might consider finding a jeweler to help me with this)!

Thanks!

http://artcourant.com/badChips.jpg[/QUOTE]

Re: need advice on soldering on my n800!
 

Even though your unit is out of warranty, you might consider forwarding your findings (and the pictures) to Nokia Technical Services... that is obviously a lapse in "materials and/or workmanship" in the original manufacturing process, and they should offer to fix that for you free of charge, regardless of warranty status.

Re: need advice on soldering on my n800!
 

Brian,

I would not jump to the conclusion that this was a Nokia induced defect.

The photograph shows a scratch from what might have been a screwdriver. The damage could have been caused by someone slipping while opening the N800.

I'm not implicating our owner, Xandor...this damage could have been done before he bought it. Xandor did state he has had trouble with it "for a while".

The photo shows mechanical forces were at work here tearing those components off the substrate.

It would not surprise me that some N800 NITs sold on eBay are victims of this type of damage. Big box stores like Best Buy, etc. are supposed to send customer returns to their source, but sometimes they sell them to customers instead, which is why I always insist on looking at an item at retail for signs that it might have been a customer return. I had this experience at a Walmart & a Target store both on the same day when I was looking for a GPS. Both stores tried to sell me items as if they were new but which I determined had been customer returns.

It is most possible that this unit was not a defective device shipped by Nokia but rather one damaged in the field by someone else. The scratch has me thinking it was caused when opened carelessly. Once again, I am not implicating Xandor, but it appears to me that someone slipped with a screwdriver while trying to open this NIT and did the damage.

M5

Re: need advice on soldering on my n800!
 

Yes, I think that holding Nokia responsible for this after an expired warranty would be pushing things. So my question still stands: does anybody have any idea what would be required (for me) to repair this? What (value of) chips am I missing?

thanks,

xandor

Re: need advice on soldering on my n800!
 

The bad news is, the pc board looks damaged, so it isn't as easy as replacing those missing discrete components. There are a couple "pads" (some people call them "lands") that appear from your photo to be torn away. The board is a multi layer board (more than 2 layers, meaning there is stuff in the middle that is inaccessible). It might be possible to use a conductive epoxy, but that is not a guarantee. Furthermore, as you know, the type of component (R,C, or L) that is missing and it's value in ohms, nanofarads or microhenries, has to be known.

Maybe you can find an N800 with a cracked screen, which has a good motherboard as a parts donor to fix yours. Check eBay.

Maybe Thoughtfix has an idea what components are missing on your unit and their values.

~~~~~~~~

The OP has a unit that doesn't appear to have any PCB damage. He just needs to resolder his USB connector back in place. Xandor's unit is far worst off.

Sorry.

Re: need advice on soldering on my n800!
 

Wow, yeah, I had noticed the damaged pads on that one item, but was thinking that there is still enough copper for the solder to stick to. As for the layers, do you mean that there are actually components sandwiched in the middle of the board somehow?! That would make it very scary to attempt any sort of soldering!

As I say, I'm in the middle of Mexico, which makes getting stuff from Ebay and the like a bit...complicated.

And I'm not the original owner of this tablet, though it appeared to be in good condition when I got it, and performed fine for many months. Odd...

(and, yes, I had pm'ed ThoughtFix. I'm hoping now that he might have access to schematics...)

Thanks a lot for your input!

Re: need advice on soldering on my n800!
 

Value of the missing components is so low that you can't even measure it ;)

But because pads are torn off, it is very hard to fix it

Re: need advice on soldering on my n800!
 

Oh, you mean because they're so teeny-tiny?:p

Meanwhile, I did find a pdf of the schematics, and it appears that these components are, indeed, part of the touchscreen circuit, either caps to ground, or resistors in series with the sig path. Unfortunately, the PDF isn't quite clear enough to be able to determine precisely which components I'm missing.

Here, in case you're curious, I've just uploaded a copy to my server which you can find here. It's actually pretty interesting to look at, being several pages long including a photo of the nekkid board!

Meanwhile, as I write this, the entire school age population of my town is marching by my door, drumming and blowing bugles, this being Mexico's independence day.

Viva!!

Re: need advice on soldering on my n800!
 

Well, I'm still determined to see if I can't at least effect some kind of kludge (yes, I am that stubborn):D. I might be able to just bypass the damaged pads if I can just figure out what components go there; just need a couple of leetle caps and resistors to fix this $300 baby, and judging from the schematics nothing connects through to the other board side. I now see that my posting of a link to schematics is redundant since there is already a thread (scroll down!) on it. Problem is that this PDF, which seems to be scattered throughout the web, isn't sharp enough to see details, such as the components I'm concerned with (F3 on the "Component finders" page).
Is there anybody reading this who might happen to have a hard copy and who would be kind enough to share with me which they are? Also, I think some of the resistors are labeled with the value "10R"--what does that signify?

Thanks much for all your input!:)

Re: need advice on soldering on my n800!
 

xandor --

These components seem to be tied to the X1501 connector, so the section of the schematic in question would be on page 3 of the schematic you linked to...

The next question is to determine what pins on that connector are (supposed to be) electrically connected to the missing parts on your circuit board. It's hard to tell from your photo what pin numbers those might be... it's a 50-pin connector, but I'm not sure where the pin numbering starts. Usually it starts in the upper left and proceeds clockwise. This would indicate that the components in question are connected to pins 26 & 27, which are the X- and Y- pins for the touchscreen. These pins are connected to resistors 1510-1513, all of which are 1% 10-ohm resistors (probably 1/4 watt, based on the size... 1/2 watt at the most), labelled on the schematic as 10R, to resistors 1514 & 1515, both 1% or 5% 1 megohm resistors, a zener diode pack (1520, the square component) and to capacitors 1509-1514, all of which are 10 nF (nanofarad) capacitors.

... it'd help to see a high-resolution picture of that entire connector on your circuit board, especially if there's any markings to indicate pin 1 and/or pin 50 .... that'd help narrow it down. Once we've determined that, for sure, we can follow the schematic and the foil pads on the circuit board to determine which components are missing and what their values are....

Re: need advice on soldering on my n800!
 

Briand,
Yes, what you say is correct, although I'm not sure why you are focusing on X- Y- (26,7) at the expense of X+,Y+(24,25). And, naturally, these 4 pins are bordered on BOTH sides by a ground pin...
I've tried doing a bit of tracing, including on that connector, but I think I'm getting false continuity signals due to caps getting charged, if that makes any sense.
That connector does NOT have any markings ID'ing the numbering.
Again, I was hoping to ID the parts via somebody who has access to a hard copy with a clear map on the final page, which would just show everything. I can ALMOST make out the IDs on it but not quite...! (again, F3, maybe also E3, on the grid). I THINK it's two resistors sandwiched by two caps on my damaged row--pretty sure I can discern the C's and R's but not the numbering.
I must say, though, that just after I made that last posting, I noticed that the OTHER side (right-hand on the schem) of those resistors and caps connect to 4 touch terminals on the OMAP chip, so there probably is indeed a pass-through to the other side of the board (even though this would seem to be underneath the headphone jack!), and this might make my task, given the state of the pads as others have accurately commented upon, nearly impossible (my goodness, am I admitting that? No...).
But MAYBE I'm lucky and the three items I'm missing are NOT at the points that pass through (but how to tell...hmmm...).

Meanwhile I'm just happily obsessing along...
The tablet IS useful for listening to BBC (and not much else) in its present state, though (assuming it still is the same as before this last disassembly:)).
And, hey, thanks a lot for clarifying the values on those "10R" resistors, etc.! Really appreciate your interest in such an obscure topic!

Re: need advice on soldering on my n800!
 

If the parts are the same in the N810, I can slip you a copy of the N810 schematics (the N810 ones is in perfect quality)

Re: need advice on soldering on my n800!
 

qwerty12 --

you could accidentally slip that copy towards me, as well, and you'd not hear a peep of complaint!! ;)

Re: need advice on soldering on my n800!
 

Well, from the picture, I cannot tell if the connector is being viewed upside-down or not. I assumed not. Then I assumed standard pin-numbering, beginning on the upper left (not pictured) continuing to #25 on the top, then starting at #26 on the lower right corner, and proceeding to the left towards #50. :)

Understand there are no silkscreen markings on the PCB... was wondering if there was a "pin 1 indicator" on the connector itself. Sometimes, it's little more than a tiny dimple at/near the #1 connector... that's why I asked if you had a (high res) photo of the entire connector.

I spent a good deal of money in school, studying electronics engineering, only to subsequently springboard my "career" from my (hobbyist) background in computers and programming... and then relegating all that education, largely, to hobby activities! ;) It is fun, mind you, designing and building all sorts of nifty gadgets, etc... and (when possible) repairing the odd bit of electronics here and there for friends & family...

Re: need advice on soldering on my n800!
 

Say, your PM box is full. I'd not mind a copy either. ;)

Re: need advice on soldering on my n800!
 

I'd appreciate the item qwerty offered as well. It appears the forum supports file attachments and links. ;)

Re: need advice on soldering on my n800!
 

Ok, well, largely thanks to Briand, plus finally being able to at least discern a starting "C" from a starting "R" on the blurry schematics, along with some deduction, I know precisely which three components I need. I nearly lost my eyesight yesterday trying to solder a scavenged 1meg resistor into place (sort of), but now think I'll adopt a different tack and see if I can't attach an auxiliary mini-board with larger components, attached to the three required points (+ ground) using very fine magnet wire, perhaps. I've found a little "pocket" where I could place this. I won't get to this for a few days, but I'll post back my results.

Re: need advice on soldering on my n800!
 

good deal!

would love to see a photo of the finished work, as well... and I promise not to criticize your breadboarding technique. ;)