Epic 4G Touch-stone mod details [LOTS of photos]

[darrenf]

[2011-10-05 UPDATE: For another version of this mod that moves the charging coil into the back of the phone, look at my follow-up post #15 in this thread. -df]

Some disclaimers up front:

* In this mod, I applied the touchstone charging coil to the *outside* of the phone. Some of you won't like this for aesthetic reasons and I can't fully disagree, but I think that the function justifies the change. I chose this for a few reasons:

1.) While the charging coil is very thin, this phone is *tight*. Unlike the Nexus S 4G which I modded with both an internal and an external charging back, the back door on this phone doesn't curve around the sides of the phone and as such doesn't have enough structural strength to hold in even a little extra thickness. If someone wanted to try placing the charging coil inside, you might be able to pull it off, but I decided to not even try. [2011-10-05 UPDATE: It is actually achievable -- see post #15. -df]

2.) The back of this phone is impossibly slippery -- to hold *and* to stick to a Touchstone base which has a slippery mating surface (the outside ring is where the phone contacts the Touchstone). Putting the charging coil on the outside of the phone and covering it with vinyl meant that it would stick to the charging base very well. The slippery surface was also affecting my grip on the phone. I had to grip both sides of the phone because cupping the phone on my fingers, it would slip out of my hand. Vinyl sticks to the fingers a little better, allowing for easier one-handed operation. For this reason I would have applied a sticker to the back with or without this mod. I don't want to over-sell this though -- the flatness and light weight of the phone will still work against you when operating it in this way.

* This was a pretty delicate mod. Don't embark on trying it unless you really can afford to destroy your phone. I have some more upgrades on my account, so at most I'm out $200, but because of the cutting that has to be done on the case, had this gone wrong I would *not* have been able to return my phone for a replacement. I can't imagine what they will say if I ever take it in for warranty repair.

* Following this mod, the digitizer sensitivity is compromised while on the charger. It's the same kind of thing that happens when the phone is on the USB AC charger but worse. As a result, I can't even put in my unlock pattern most of the time. If this phone is unlocked, touch input works OK but not perfectly. This will be a hassle in the car because I won't be able to operate everything while it's on the base. I don't know if this is a function of the charging current, coil or where the power wires are run. If someone knows more about the physics of this, please fill me in. I plan to do some experimenting and I'll report my results. [2011-10-05 UPDATE: This problem is avoided if the phone is grounded, in my case by plugging it into a car stereo with a phono cable, or if the phone is fully charged. Others are working on a related problem with some AC chargers so I'm waiting to see if a fix is forthcoming from that group. -df]

Given those caveats, I may be the only person who will even attempt this mod, but at the very least, read on to see what the inside of your phone looks like!

Here we go, in excruciating detail...

Start with a Epic 4G Touch and a Palm Touchstone charging back:

Peel the charging circuit out of the Palm charging back:

Remove the plastic covering the charging circuit:

Test-fit to figure out where the charging coil should be located:

Take the back off the E4GT and remove the 6 screws holding the back on:

Looking at the screen of the phone, run a removal tool (I used the one that looks like a plastic guitar pick) around the groove at the edge of the screen to pry the back off. Note: unlike the Nexus S 4G and the European GSII, there is no trim ring around the side to remove. All the plastic is in one piece:

When removing the plastic, you'll want to ease it over the USB connector at the bottom first because you'll have to slide the plastic up a bit to get over the headphone jack at the top. You will now be looking at the circuitry. Pry up the three connectors (orange arrows) and remove the three visible screws (red arrows):

[ON TO PART 2...]

 

[darrenf]

[...CONT'D FROM PART 1]

Let me stop here and comment on how well built this phone is. What you see here is the entire phone disassembled. On the left is the screen, bonded to a Magnesium chassis. In the middle is all of the circuitry (I can't believe that's all there is to it!!) and on the right is the plastic surround which locks it all into place and houses the speaker and vibrate motor.

Many reviewers have commented on the cheap materials that Samsung uses in a lot of their phones. It's clear from this that they aren't being cheap but using the *right* materials for the job. If I happen to drop my phone on the ground, I can't think of a material better than plastic for absorbing the impact. At the same time, to get strength, they include a Magnesium chassis to give the screen a rigid base and to avoid flexing.

For completeness, here's the other side of the circuit card:

and here's the bit I'm interested in, the USB connector, with the charging pins annotated:

This is where we run into the first hiccup. The USB connector is tightly sandwiched in between a boxed-in section of the Magnesium frame and the plastic in the "butt" of the phone that holds the speaker and vibrate motor. They are designed to the *exact* shape of the connector, so wherever I route wires I will have to notch out material to make room for the wires.

My preference is to notch out the plastic because it won't rub insulation off my wires like jagged Magnesium will. The problem is that the USB connector and wires to which I have to attach are face-down in the metal frame and there are no holes through the PC board around the connector. So, I made my own. Working with a small gap between the back of the USB connector and the back of the PC board, I used a set of impossibly small drillbits that I bought at Harbor Freight to make a hole big enough to pass a wire (sans drill - I twisted the bit with my fingers). End result:

The wires that I chose for this project were pretty small so I decided that it would be best to run the target current over them for a while to make sure they didn't melt. This isn't a perfect test because heat in the battery compartment will increase resistance accross the wires, but I tested a 12" length of wire and given that the finished product would only be carrying current about 2", I expect I will be OK:

At first I soldered the positive leg to the USB connector pin carrying +5V, but the connection was subject to too much torque as I threaded the wire back through my hole and it was generally just not an encouraging solder joint, so instead I soldered to the surface-mount thingie (resistor?) that is first in line off the trace coming from that pin. This proved to be a much better choice:

The yellow wire in the background is the ground leg. I soldered that to the other side of the PC board where there were easy-to-access solder points. I soldered the ground first, before threading the +5V lead to ensure that I didn't melt some of the jacket on the +5V lead when heating up the shiled on the USB socket.

Now flip the PC board over and insert it into the Magnesium frame, replacing the three screws and three connectors. Here is what the wires look like from that side:

Now we have to get the wires into the battery compartment. The first part of that is chipping away some of the battery compartment shell (I just used wire clippers) like so:

Use some shrink-wrap to protect the wires where they pass over the metal:

[ON TO PART 3...]

 

[darrenf]

[...CONT'D FROM PART 2]


Next, remove the speaker/vibrate motor from the back shell of the phone and file down the plastic along the path of the wires. This is important because this plastic sandwiches tight against the PC board:

Next, file down the battery at the point where the wires pass. Again, everything is *tight* in this phone:

Turning my attention back to the back cover, locate the charging coil in place temporarily, mark the area of the charging circuit and cut it out of the back:

The charging circuit is the thickest part of the charging coil, so notching out behind it avoids a bump on the back of the phone and gives easy access to the solder posts from the inside.

The next step can be avoided. It's possible to mount the whole charging assembly, as removed from the Pre, on the back of this phone. I decided that I wanted to remove the plastic to make it that much thinner so I had to find a way to transfer the metal studs, coil, shield and charging circuit to the back of my vinyl overlay without loosing their locations. If you want to do this, sacrifice a piece of vinyl to get the backing off of it:

Place the backing, *shiny side up* onto the charging coil, then trace out the components you will ultimately transfer to the vinyl back:

It may not be clear at this point why I'm doing this, but it's because the shiny side of the paper backing won't stick to the vinly, allwing it to be peeled off, along with the Palm black plastic backing, after the parts have been afixed to the vinyl sticker.

At this point, make the vinyl sticker that will be exposed on the back of the phone. If you don't have access to a vinyl cutter, grab a cool sticker from a surf shop or chop up a bumper sticker. I used a 2.5" square sticker with rounded corners.

In this photo, I've afixed the vinyl sticker (showing through in red) to the surface you saw in the photo above, then I removed the black Palm-supplied plastic, exposing the bits that will go up against the back of the phone:

After this, peel away the sacrificial paper backing to reveal the parts that will be afixed to the back of the phone (sticky side up):

Lay the phone back on the table, line up the sticker/coil so that the charging circuit lines up perfectly with the hole in the back of the phone and so that the sticker is centered and not crooked:

[ON TO PART 4...]

 

[darrenf]

[...CONT'D FROM PART 3]

Here's the view from inside the back cover:

Next, cut the leads from the phone to the appropriate length (in this example, the positive is shorter so that they don't cross one another once the phone is closed) and solder to the charging circuit. In this arrangement, the +5V terminal is closest to the bottom of the phone:

Afix the back to the phone and test!

I took several photos and chose this one because you can see the charging coil and studs most clearly. It's a little deceptive though, because they add very little to the thickness of the phone. I tried to take a photo from the side to show the thickness, but when I was looking at the side straight on, the coil just disappeared from view.

NOTES

* The compass is unaffected by this mod. I tested it to make sure. That's not really surprising because the studs on the back of the phone are metal, not magnets. What is surprising is that the compass isn't even affected when the phone is on the touchstone base. The base is where the strong magnets are located that lock the phone in place.

* I am not available to do this mod for others and you would be crazy to trust me to do this to your phone. Hopefully, I've given plenty of detail here to lead you through the mod yourself or to allow someone else to offer this service if there's an interest.

Feel free to ask questions!

-darren

 

[BRIVERS73]

Wow, nice write man! That's quite a feat u pulled off.

 

[cacherpaderp]

You sir, have monstrous balls. I wouldn't dare even unscrew my phone a few days after it just came out.

 

[tronthedon]

I won't be "Frankenstein-ing" my phone like this due to obvious reasons, but I commend you for at least taking the time to write this up. I'm sure someone out there will try it, and if anything, it was a fun read for me. Very cool indeed.

Should even be on the AC front page! (and on XDA)

 

[darrenf]

Thanks guys!

After seeing how packed the phone components are, I decided that I would give up on the touchstone and switch to the Samsung desktop and car chargers -- particularly since they may incorporate audio out ports (the Samsung store listing is non-specific on this point). I removed my Touchstones from service and charged over USB for a day and a half, but three things convinced me that I had to convert it:

1.) Samsung shows no sign of releasing the desk or car docks any time soon,
2.) people using Samsung docks with other G2S phones have issues getting all audio out through the dock so I might have to hook up an audio cable anyway like I do when Touchstone charging, and
3.) I found myself setting the phone on the Touchstone just to prop it up. After years with the Touchstone, USB charging seems awkward!

Here's a pair of bonus photos for those of you curious about the chips that were used in this phone (click to download full-res photos of the circuit card -- may require some further enhancement to read part numbers):

http://dl.dropbox.com/u/6578838/Linked/E4GT-1.jpg

http://dl.dropbox.com/u/6578838/Linked/E4GT-2.jpg

-darren

 

[rlanza1054]

Love the mod! I did a mod like this on my Pre so that I could use the Naztech charger with the touchstone.

I decided to purchase (when it comes out) the car adapter (not the charger) for the S2 in my house, because it will be easier to display and plug in to charge, instead of the 'stand' that I saw on Samsung's website.

The car adapter can display the phone in both portrait and landscape mode, and because the phone is on an adapter with a suction cup, it can be used with any flat surface. The phone will just slide into the adapter, hence be easier to get it to plug into the usb port, so your not fiddling with a wire in your hand to plug it in.

Of course, when it becomes available.

Again, loved the mod!

Rob

 

[roninlb]

Have you checked to see if the phone still charges if you put the phone in a case like the TPU one?
Thanks.

 

[garrettfarnum]

This would be awesome if you could make a case that has a micro-USB plug on it for the touchstone. So that way there would be little to no modding on the inside of the phone.

 

[Cvballa3g0]

You sir, have monstrous balls. I wouldn't dare even unscrew my phone a few days after it just came out.

This is exactly what was going through my mind while scrolling through the photos. I don't even have the balls to root my Bionic atm.

 

[ysaykin]

Would this be easier to do with a case mod for the phone? And have inductive charging charge through usb? Just wondering.

 

[darrenf]

This would be awesome if you could make a case that has a micro-USB plug on it for the touchstone. So that way there would be little to no modding on the inside of the phone.

I considered this precise concept when I modded my Nexus S 4G, but couldn't find a flush USB micro connector and really didn't want to give up easy access to the USB port. With an internal mod you maintain full use of the USB port (and MHL in the case of the E4GT). Unless you change the battery or take off the back to change the microSD card, the wiring is wedged in and doesn't move so your solder joints won't flex. With an external mod you flex those connections every time the connector is unplugged to allow use of a USB or MHL cable.

What would be great for an external mod is a micro USB cable that comes out at a 90-degree angle, with healthy (26gauge+) pigtail wires that you can solder straight to the touchstone further up into the case. That way you don't flex solder joints at the micro USB connector. Something similar to this:

Amazon.com: StarTech.com UUSBHAUB1RA 1 Feet Micro USB Cable - A to Right Angle Micro B: Electronics

but even more flush fitting at the bottom if possible.

If you try this out be sure to post your results!

-darren

 

[darrenf]

OK, I got bored and wanted to see if I could make this mod more elegant by moving the charging coil into the back of the phone. Things I knew up front: 1.) by removing the vinyl on the back of the phone it will not stick as well to the touchstone or my hand and: 2.) because of it's thickness the charging circuit would have to be placed in a cut-out in the back (which, coincidentally, I had already created in the first mod).

Here is the result:

And here is how I got to that point:

Working with another Pre back, I removed the positioning studs and charging coil/circuit/shield. I worked hard to get as much adhesive gum off of them as possible:

I then placed the phone back on top of a touchstone, then positioned all four studs and the charging coil on top of that. The studs hold everything in place and you can move the back around under the studs until everything is in just the right place:

Now we get to a part that I would skip if I did it again. I decided to heat up the studs with a soldering iron to embed them into the plastic. I did this because I thought that glue would not work given the amount of flex the back cover would be subjected to when being removed from the phone. My plan worked, but ultimately it took a combination of melting the plastic *and* gluing them with CA cement to keep them in place through removals of the back. I would suggest finding just the right glue instead as this will keep the back of the back cover from showing lands where the plastic is heated:

I am toying with the idea of putting something on those flat spots on the back to get better grip on the touchstone. I just haven't figured out what to use. It needs to stick like epoxy to avoid rubbing off but remain slightly sticky to grip the Touchstone surface.

At this point, I tested the current coming out of the coil to make sure that I situated it correctly and I then I put some CA cement under the three tabs of the shield where they extend past the coil. Next I trimmed the lead wires coming out of the phone and soldered them to the charging circuit contacts. After that I put some electrical tape (man that stuff is thick) over the charging circuit to prevent the solder pads/wires from contacting the battery which has a vaguely conductive looking Samsung sticker on it:

Once the cover was put back on the phone, the back looked like this:

All that remained was to put a sticker over the charging circuit. This side of the circuit is completely flat which helps:

And that's it. It doesn't stick as well without vinyl on the back but it looks and feels stock except for the sticker and the flats where I melted the studs in (and the latter could be avoided). Here are some photos that attempt to show how flat it is. There is virtually no bulging and absolutely no creaking or flexing:

[That one's out of sequence so it's missing the sticker -- it's just a great perspective.]

-darren

 

[enfurno]

You are a mad freaking scientist!

 

[morrison0880]

Awesome mod darren! Quick question...have you seen this mod for the Nexus?

http://forums.androidcentral.com/ve...od-palm-touchstone-no-soldering-phone-11.html

I'm assuming you're pretty mechanically inclined, so I was wondering if you think a mod like this would be possible with the Epic Touch? I can't really express how much I miss the touchstone from my FrankenPre2. As a car dock it was absolutely amazing. Now, with ICS roms popping up for the Epic, gaining touchstone functionality could make it almost the perfect device for me. I'm not willing to go into soldering and your mod at this point (maybe in the future), but if somehow this method were possible, I would be in heaven. Not sure if you are monitoring this thread anymore, but if you are, let me know what you think!

 

[darrenf]

I like that mod -- particularly for the use of foil contacts because it lets you take the battery door off without worrying about the connecting wires. I didn't understand at first how the foil stayed in contact all the time -- phones like the Pre used a spring-loaded contact on one side to maintain contact through stresses on the phone -- but I guess since it's at the edge, mechanical force from the tabs is sufficient to keep them touching. Nice!

I do worry that this would show a significant bulge. I've used a GNex and I know that there isn't enough room under the battery door for the charging circuit, let alone the additional plastic that was left in place in this install. I also bet that the magnets he installed inside the door affect the compass. The stock Pre back uses metal studs that are non-magnetic so they don't affect the compass.

I'm getting ready to sell my touchstone-modded Nexus S 4G and GS2 Epic 4G Touch since moving to the GNote:

http://forums.androidcentral.com/samsung-galaxy-note/152631-galaxy-note-touchstone-mod-photo-heavy.html

which I absolutely love. I'm betting that you already have a EpTouch but if not, and if you want a Touchstone modded one, look for my forsale ad soon.

-darren

 

[darrenf]

Oh, and to answer your question: you might be able to use foil contacts to avoid running wires between the phone and the back but you will still need to route wires from the foil back to the USB charging port. The GNex uses contact charging which is why it has those visible charging contacts. The EpTouch has no such thing and the USB charging port is really buried in there -- even more so than on the Nexus S 4G or Note.

-darren

 

[darrenf]

It is time for me to sell this phone. I've been using the Galaxy Note, with Touchstone mod of course, for almost a year as this phone has set on my desk begging for a new home.

I can sell it as-is or reverse the mod and sell it stock. In case someone here wants a touchstone-enabled Epic 4G Touch, I am offering it for sale here first.

For $300 I'm selling the phone, a stock cover (in case you decide to undo the touchstone mod), a touchstone, Palm USB cable and Palm charger. It comes in the original box with original books but no headphones (I've misplaced them).

If you have an interest, PM me and I'll give you my contact information.

Thanks!

-darren

p.s. - I did ask for and receive permission to post this listing before posting it. (Thanks Cory!)