* TUTORIAL* Palm touchstone mod

d94 said:

While your correct that its a little complex and theres a few sub-boards and switches, me being a sprint tech and working on dozens of other samsung sliders, particularly the moment as of the last year and based on the pictures from the FCC website it's really simple to take this phone apart - just a few screws under the battery cover, the back pops comes off and boom theres the main circuit board with a few flex cables and antennas plugged into it..pop the connectors off and you have yourself the mainboard

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Thanks, that's what I was hoping to be the case.

It should be as simple as soldering two cables to the appropriate spots on the MicroUSB header and then routing the wires into the battery compartment and out to the back cover.

I can confirm that the touchstone dock screws up your compass, at least temporarily. A warning message pops up regarding the magnetic field. Recalibrating seems to restore the compass. However, I did not test with the actual coil inserted into the case. The coil has metal disks that might become magnetized, potentially not allowing for recalibration unless you remove the back cover.

I attached the touchstone coil to the battery cover similarly to how the OP did in his picture and there was only a slight bump in the battery cover when it was put back on the phone. Not bad at all. Unfortunately the shape of the back of the phone makes it so that it does not connect well with the touchstone dock and it just barely stays in place when placed on the dock.

Assuming that the touchstone puts out 5V, then the easiest way to do this is to solder some small wires to the touchstone circuit board directly - bypassing the two metal pads that the pre uses - and running those wires through one of the tree holes that are clearly visible to the right of the SD card slot when you remove the battery cover. The wires could then be run to the USB port and soldered to the correct pins. Care must be taken to find the correct pins however because although microUSB has 5 pins, the USB port on the Epic has 7 pins connected to the circuit board according to the pictures in the OP's post.

If the touchstone puts out about 3.8V however, then I am at a loss. Connecting a power source directly to a battery (especially Li-ion) is very dangerous. We have no way of knowing what kind of voltage protection is included on the mainboard that protects the battery.

I will check the touchstone voltage and which USB pins to connect to tomorrow night (hopefully). I've just been too busy lately to get into a lab to check.

The touchstone is NOT connected directly to the battery on the Palm devices. You can literally make a bomb this way. Do NOT try to apply voltage directly to the battery contacts.

protocol6v said:

The touchstone is NOT connected directly to the battery on the Palm devices. You can literally make a bomb this way. Do NOT try to apply voltage directly to the battery contacts.

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oops, you're right- i looked closer last night and saw that the touchstone contacts go to the circuit board.

but let's not get crazy here- you'll overcharge if you leave the battery on the charger too long w/ a direct battery connection, but you ain't making a bomb... ;D

edit: i mean, batteries *can* explode of course, it's just really, really, really unlikely. iirc, most (all?) li-ion batteries have built in circuits to prevent it from getting too overcharged.

Roisen said:

If the touchstone puts out about 3.8V however, then I am at a loss. Connecting a power source directly to a battery (especially Li-ion) is very dangerous. We have no way of knowing what kind of voltage protection is included on the mainboard that protects the battery.

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The touchstone does NOT put out 3.8V. It puts out almost 5V. It shouldn't be difficult to use a multimeter and figure out optimal solder points. Honestly, the hardest part is the disassembly and routing wires. Under no circumstances should anyone wire the touchstone directly to the LiIon battery. That is can be quite dangerous without a protection circuit.

Maybe I over emphasized with the bomb part, but it is still incredibly dangerous and could end with injury if you charge a Li-ion batt directly.

You should have checked while you had it open. Just plug the charger in and use a voltmeter to check which pin coming off the usb jack is 5v.

Then just solder to that pin and solder the negative to any ground in the phone.

d94 said:

i would of if i had one on hand.lol ill have to try and grab one tomarrow
im guessing i put it on the 5v setting and use the + to find the 5v and the - for the ground? and how would i check for a ground

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If you have an old analog multimeter put it on the 5V range. Most modern digital multimeters are auto-ranging.

Any ground on the circuit board should be interconnected, hence the term "common ground." There are many possible spots to solder your negative terminal wire. Pick the largest one since it is probably easiest to solder. You can consider using the solder point for the connector for the negative terminal of the battery.

Then, with your charger connected and plugged in, test to see which of the 5 circuit traces coming from the MicroUSB header shows +5V. Visually confirm that this corresponds to pin #1 in the pinout diagram.

Obviously when testing, be sure to only use the tip of your multimeter to prevent accidentally short circuiting across multiple points on the circuit board.

Some high-resolution photos of the area around the USB connector, front and back, would be helpful as well.

d94 said:

still havent gotten my hands on a multimeter..anyone else done this yet?

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I haven't actually done the mod yet, but I did take the phone apart. It was actually not that difficult. Reassembly was more difficult for me since the case takes some force to snap back on.

1.) Briefly, after removing the back battery cover and battery, you will see 7 small Phillips size 000 screws (very small). Remove these and put aside in a place they will not roll/drop.

2.) Starting near the power button, carefully pry the plastic case around the edges using a thin plastic wedge. Do not use a screwdriver, as you will scratch/break something.

3.) Disconnect the small white antenna connector on the lower right-hand side.

4.) Disconnect the two small ribbon cable connectors to the motherboard. Very carefully pry these off from the side opposite the cable, being very very careful not to bend any pins.

5.) The circuit board is now free and will simply lift off. Be careful as the camera sensor is attached via a flexible ribbon cable, as is the headphone jack.

In terms of the +5V connection, there were not many options. Many of the components are very tiny and too hard to solder without specialized equipment. After checking many resistors, I didn't find a suitable one that would be any easier to solder than directly to the USB header.

That being said, in my opinion the easiest place to solder would be directly on the USB header itself. This is on the back-side of the circuit board. The correct pin is nearest the headphone jack. It is also indicated by a small diagonal gold arrow. You will need to carefully solder to this pin, and this pin ONLY. A short circuit here would be bad.

Carefully route your positive wire through the space for the camera sensor, and reassemble the circuit board. Now, on the circuit board there are many places to solder a ground wire. Take your pick. The easiest is probably one of the four solder mounts for the USB header. Either that or the headphone-jack side of the large resistor would be my picks, or any of the large ground buses (gold thick lines) on the board.

All the wires can then be routed through the potentiometer adjustment holes (R1, W1, W2), and the phone reassembled and screws reinserted.

From there, simply solder to the Palm Pre touchstone coil, and voila....you have wireless charging at almost 500 mA.

I should put the disclaimer that I have not actually done this mod yet, and any information above is based solely on my 15 minutes of tinkering. Use this information at your own risk, I am not responsible if you fry/brick your phone, or damage your compass.

I went into my lab all ready to do this mod and ran into two speed bumps. First, I was trying to confirm the voltage output and was seeing very strange results on the oscilloscope. It was pulsing once a second for one third of a second at about 500mV. I tried placing a resistor between the oscilloscope and the touchstone coil circuitry to see if it was trying to sense a load before it output it's voltage, but no go there. In the end I was unable to get the coil to output anything other than those slight pulses.

Secondly, After removing those 7 tiny screws, I was unable to get the plastic back off. The top part seemed to pull off very easily (note: be careful of the headphone jack. You'll need to pull the cover out a little to clear it when removing the back), but I just couldn't get the sides or bottom pried off.

Roisen said:

I went into my lab all ready to do this mod and ran into two speed bumps. First, I was trying to confirm the voltage output and was seeing very strange results on the oscilloscope. It was pulsing once a second for one third of a second at about 500mV. I tried placing a resistor between the oscilloscope and the touchstone coil circuitry to see if it was trying to sense a load before it output it's voltage, but no go there. In the end I was unable to get the coil to output anything other than those slight pulses.

Secondly, After removing those 7 tiny screws, I was unable to get the plastic back off. The top part seemed to pull off very easily (note: be careful of the headphone jack. You'll need to pull the cover out a little to clear it when removing the back), but I just couldn't get the sides or bottom pried off.

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Are you using the factory Palm charger with the Touchstone? You have to use a Palm charger or modify an standard microUSB charger in order for the Touchstone to turn on properly. The touchstone is expecting one or both (I forget now) of the data pins shorted together to enable fast charging mode.

You need to pry the back cover off, starting near the volume or power switch, whichever is looser. Slide a thin plastic shim in between, it will come off. Just be careful.

I will warn you in advance that it is not easy to solder to the USB header. You will need a very fine tip, and possibly some magnification depending on your eyes. You will need very thin and flexible wire and careful planning to route the wire in a way that the case with close, since the assembly wastes little space.

Good luck.

This post is worthless without pics I can figure out where the point is closest to the headphone jack, but I have no clue which is the common ground. I'd also like to see how people are removing the magnetic portion and attaching it to the Epic cover. I've got a Touchstone just waiting to be intergrated into my phone.

Have you noticed any affects on the navi, compass, etc once removed from the charger?

Thank you for this! I'm having a hard time distinguishing where you soldered the wires onto the phone itself, so hopefully it'll become more clear once I take the phone apart. Is the hole you drilled above the battery terminals on the phone itself? Which color wise was soldered to which terminal on the battery cover? Is there a writeup somewhere on how to disassemble the phone to do this? When it's on the dock and you have the USB charger hooked up to your computer, does it still allow transfering of files...ie does the charging, mass storage, etc screen popup? Highly unlikely since it's not a wired connection, but I figured I'd ask. Does the red charging light come on, or how did you confirm that this is proper voltage? Based on your last pic, it's sitting on the Touchstone but the charging light isn't on.

At this point I've removed the Touchstone stuff from the Palm cover and transferred it to the Epic cover since I see how you did it. I even transferred the 4 little metal discs...I wasn't sure if you did the same based on your pic. It gives a minor bulge, but the cover is staying attached. At least for the moment I have a stand!

Pic taken with my Treo 755p, that's been through hell and back (came out of my tankbag doing 80 one night!) and still kicking!