Hello all, I am a new 770 user thanks to Woot.
I am also a computer modifier, and like to fix annoying design features in products. In this case it is hauling a 5volt wall wart around to charge my 770, when there is perfectly usable 5volt power on the USB connector.

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This modification will make it so that your Nokia 770 can charge off of a USB port, rather then hauling around the wall-adapter. All you need is any normal mini-USB cable.

What makes this possible is that the wall-adapter puts out 5volts, which is the same voltage on a USB port.

This modification is a DO AT YOUR OWN RISK modification. It will certainly void your warranty. I am not responsible for any damage to your device by following this guide.

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First remove the battery, cover, and memory card.
Then remove the five torx screws on the back of the 770.
Two of them are located under plastic caps at the top.

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Using a plastic prying tool (iPod repair websites sell them) remove the bottom plastic plate that covers the I/O jacks
(I actually used a small screw driver as I can live with small marks in the plastic)

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Remove the faceplate.
The LCD may stick to the faceplate, but it is not glued in place, it will come undone with a small amount of pressure.

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Carefully fold the LCD over to expose the PCB.
There are several tabs at the left hand side, and around the battery housing that you have to release to get the back-plate off.

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Flip over the PCB, make sure to pad the LCD.

It is amazing that Nokia can cram so much technology onto such a small space, and with so few parts.

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Note the location of the USB connector.
To the right of it is two small gold pads, this mate to the charging connector.
The right most pad is +5volts.
On the USB connector +5volts is on the left most pin.

I used a multimeter to determine that +5volts-charge is connected to a surface mount ferrite. It is a small gray component. This is where I will run my USB voltage to.

(I don't recommend soldering directly onto the gold pad, as then your normal charge connector won't mate with the PCB)

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I soldered a wire from Pin 1 on the USB connector to one side of the ferrite.

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Carefully put everything back together.

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Power-up before plugging in the USB connector.
Then plug-in the USB connector.
Depending on how your computer manages USB power, it may turn the port off if it doesn't mount the 770, but I find with a memory card installed it stays on.

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That is it, now you don't have to haul around that dang wall charger.
Just find any mini-usb cable and your ready to go.

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Sorry folks, I don't do these mods for others, so don't ask.

/Edited to spelling, and errors

Very nice Howto, thanks for the effort !

For tinkerers who don't have the guts to disassemble their tablet, or don't "do" precision soldering, perhaps a modified USB cable with a tip that goes into the charger connector would be a simpler approach, with almost the same result ?...

Haha...for 2 reasons...

One: I was looking around yesterday and wondering why nobody had done this before as it seemed pretty obvious.

Two: I saw those pictures on flikr earlier here: http://nokia770.com/ but didn't know for sure this is what it was and where the full writeup was.

Very nice job indeed. How difficult would this be for the somewhat-beginner? I know how (well in theory at least) to solder and have soldered stuff before but it never looks _that_ pretty.

To those of you who have been around a nokia 770 for a while- is there a downside to this? I figured Nokia HAD to have a good reason not to have just done this from the getgo? The only one i could think of was in case people plugged in two power sources at the same time but they could have easily fixed that by just using a USB for data and charger instead of what it has now.

edit: Oooh I just had an idea. I've seen a lot of talk about people having to use powered hubs to get usb devices to work. Would it be possible to send power from the power connector leads to the USB port to send power to USB connected devices? I'm guessing you couldn't do both mods at once, huh?

Seems to me that would be the exact same power result- but you're still locked into carrying that cable around too. Reminds me of my palm's charger tip- have a thing that fits on any sprint car charger BUT i still have to carry the damn thing with me.

Yes, that would work, but that is a custom cable to lose, if you do it internally then you can get a cable at any store if you forgot yours at home.
Heck I had neither the wall-wart, nor a mini USB cable with me when I started the mod at work, but asking around a few cubes and I was able to find one to borrow in minutes.

It is not difficult to do, but you just have to take care not to bridge any connections with solder, or break anything when opening it up or putting it back together. The reason mine is so clean is that I had the right wire, a expensive soldering iron, tiny tip, and stereo microscope to do it with. (Work)

The reason Nokia probably didn't do this from the beginning is because technically the charger is rated at 900mA of output, and a USB port isn't spec'ed to put out that much current. That said, I doubt it needs that much current in reality. I did this same mod to my cell phone years ago.

Yes, if you do plug-in 5volts to the charger jack, AND a usb cable the power will pass out of the USB connector.

For those trying this at home...

A "Husky" brand multi tip torx screw driver is available at Home Depot in their tool coral for about 6 bucks.

Wooden cuticle pushers found in pharmacies (5 pack about a buck and a half) can be used as plastic pry tools.

Nice posting, but on a cautionary note, I recently repaired a laptop power socket and accidentally desoldered a couple of those ferrite things. Took me about an hour to get them back in place.

They already sell these cables on ebay for sub $5, it would be simpler to just buy one. I like this idea but I'm not sure if I trust myself enough to attempt it

So...

Does this mod also allow the 770 to use any old USB keyboard without macgyvering in a separate power source for it?

Great tip, I never thought of that, I have to go get some now.

The only reason I knew it was a ferrite was because it was gray, brown are usually capacitors, and parts like that with printed numbers are normally resistors. Just FYI.

No, since the 770 doesn't send power out the USB in the first place.
(Unless you do as robbh66 asked)