DIY TF101 Keyboard Dock barrel style charger connector MOD

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DevCake

Senior Member
Mar 3, 2008
468
62
Warning . This DIY is not for the inexperienced. If you have never disassembled a laptop( and get it back together working) or worked with custom DC power applications you'll want to follow the "do not try this at home" rule. It will require some fabrication skills as well, drilling and making brackets. Once I have this perfected I'll be offering a send in MOD service.

First I need to get a Dock, I have to keep mine intact as I use it daily with my demos and android integration services. If you want yours modded for free let me know. I will guarantee you will get yours back either in the condition it was sent or working with the MOD.

For the modders following along, assumed steps.

1. Remove feet from bottom of dock. Guessing assembly screws are there.
2. Disassemble dock and look for space somewhere along the edge to add a small barrel adapter.
3. Find power leads to the battery and solder extension wires.
4. Test that extension takes charge and that factory connector still works to charge
5. Fabricate bracket for connector
6. Drill edge of case to expose connector.

Let's hope it is this simple. =]
 

verkion

Senior Member
Sep 3, 2007
350
33
Warning . This DIY is not for the inexperienced. If you have never disassembled a laptop( and get it back together working) or worked with custom DC power applications you'll want to follow the "do not try this at home" rule. It will require some fabrication skills as well, drilling and making brackets. Once I have this perfected I'll be offering a send in MOD service.

First I need to get a Dock, I have to keep mine intact as I use it daily with my demos and android integration services. If you want yours modded for free let me know. I will guarantee you will get yours back either in the condition it was sent or working with the MOD.

For the modders following along, assumed steps.

1. Remove feet from bottom of dock. Guessing assembly screws are there.
2. Disassemble dock and look for space somewhere along the edge to add a small barrel adapter.
3. Find power leads to the battery and solder extension wires.
4. Test that extension takes charge and that factory connector still works to charge
5. Fabricate bracket for connector
6. Drill edge of case to expose connector.

Let's hope it is this simple. =]

This is a dang good idea...I should have thought of this earlier! Looking at the dock, it looks like the bezel is clipped in as well. Also, the "clamp" part of the dock has some screws in it. Mechanism might be a little bit more complicated but hopefully not. You're going to need an awfully thing barrel connector to make this work. The Bezel is about the same thickness as the TF's bezel.

verkion
 

Bob Smith42

Senior Member
Jun 7, 2011
760
136
Think I am going to try this mod. Ordered 2nd dock. If I go over-my-head I will contact DevCake for help.

The issue with barrel plug on TF tablet is what to do when dock is attached?

The advantage of barrel plug on dock is charging both dock and tablet, eliminating the need for any proprietary 40 pin cable (because doc has its own), and if you want to screw around the dock costs less (still $150USD is a lot, but less compared to a spare $40USD charger). Still need to consider what to do if barrel plug charging and something plugs into 40pin connector.

I also plan to put in a slide switch to disconnect the dock battery from the tablet entirely to save juice when shut down. E.g. reports of doc losing power when attached. This could extend the stand-by life of the dock for a week or more.

Once the thing is opened up, it might be a good time to discuss placements. Everyone has different and great ideas. I have a digital caliper to measure stuff.
 
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DevCake

Senior Member
Mar 3, 2008
468
62
Think I am going to try this mod. Ordered 2nd dock. If I go over-my-head I will contact DevCake for help.

The issue with barrel plug on TF tablet is what to do when dock is attached?

The advantage of barrel plug on dock is charging both dock and tablet, eliminating the need for any proprietary 40 pin cable (because doc has its own), and if you want to screw around the dock costs less (still $150USD is a lot, but less compared to a spare $40USD charger). Still need to consider what to do if barrel plug charging and something plugs into 40pin connector.

I also plan to put in a slide switch to disconnect the dock battery from the tablet entirely to save juice when shut down. E.g. reports of doc losing power when attached. This could extend the stand-by life of the dock for a week or more.

Once the thing is opened up, it might be a good time to discuss placements. Everyone has different and great ideas. I have a digital caliper to measure stuff.

Go for it Bob,

I don't think installing the barrel connector on the Tablet is a good idea either.

I wouldn't place the connector on the front so the sides IMO are the best location but that will become clear when we see the innards.

The addition of the 40 pin connector while the barrel connector is charging is a big part of the mod. Bridging the power over to the barrel puts both power sources in parallel and this can be bad. When you attach 2 power sources in parallel that are of different voltage the voltage actually will travel to the lower voltage supply source and overload it. Remember any PC USB is 5V, not the 12 or 15 you will supply to the barrel so if the barrel is connected to the charger and the 40 pin is connected to the charger you will send more voltage back to the PC and BOOM! The universe will implode upon itself =/.

So how do we address the possibility of multiple power sources? either with a switch or an additional circuit that shuts one off when it see voltage from the other. The 3rd option is to disconnect power from the 40 pin which IMO is not an option, you want to keep that intact.

Bob if you frequent any DIY forums that deal with these kind of power MODS ask around about a circuit that will do this for you. You might want to start with RC forums, those guys know DC like no other. I'll start looking around but whatever we find needs to be small for sure.

Have you sourced some barrel connectors?
 

Bob Smith42

Senior Member
Jun 7, 2011
760
136
Good news.

I received my 2nd dock, and opened it. There are only two screws, under the rubber feet in the back by the hinge. These screws help support and hold the hinge in place. Run a plastic separator tool around the edge to open. I started in one back corner. It is tight in a few places. Do not bend the metal by the socket positions, where the metal is very thin and flexible. The front edge separates last (most difficult) using leverage of flapping open and closed the top/bottom pieces, and starting separation on one side.

I will post pictures soon. I took some and in the process of uploading. I have my digital caliper at the other office so measurements later.

There is a great position for a female socket for a barrel plug charger, behind the current charger and pointing to the back. It is between the hinge and a circuit board, so there is no leeway in width. The width is narrow, just under 5mm, so a socket needs to be thin. If we find a 4mm wide barrel socket, maybe 7mm or less high it should fit. Of course that makes a slim barrel. :)

UPDATE: On further consideration, we might trim up to 3-4mm of the hinge plate, giving up to 7-8mm square barrel socket.

The area between the battery (centered under the keyboard) and the back hinge is wide open. Literally room to drop in x4 sd cards end to end, and stack another row of x4 on top, with space left over. The entire space is about 5-10mm height. A switch can go anywhere in this area, mounted on the bottom face, which is protected by the protruding hinge.

I was thinking with all the USB ports, it might be worth considering loading up some internal USB devices later.
 
Last edited:
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DevCake

Senior Member
Mar 3, 2008
468
62
Good news.

I received my 2nd dock, and opened it. There are only two screws, under the rubber feet in the back by the hinge. These screws help support and hold the hinge in place. Run a plastic separator tool around the edge to open. I started in one back corner. It is tight in a few places. Do not bend the metal by the socket positions, where the metal is very thin and flexible. The front edge separates last (most difficult) using leverage of flapping open and closed the top/bottom pieces, and starting separation on one side.

I will post pictures soon. I took some and in the process of uploading. I have my digital caliper at the other office so measurements later.

There is a great position for a female socket for a barrel plug charger, behind the current charger and pointing to the back. It is between the hinge and a circuit board, so there is no leeway in width. The width is narrow, just under 5mm, so a socket needs to be thin. If we find a 4mm wide barrel socket, maybe 7mm or less high it should fit. Of course that makes a slim barrel. :)

UPDATE: On further consideration, we might trim up to 3-4mm of the hinge plate, giving up to 7-8mm square barrel socket.

The area between the battery (centered under the keyboard) and the back hinge is wide open. Literally room to drop in x4 sd cards end to end, and stack another row of x4 on top, with space left over. The entire space is about 5-10mm height. A switch can go anywhere in this area, mounted on the bottom face, which is protected by the protruding hinge.

I was thinking with all the USB ports, it might be worth considering loading up some internal USB devices later.

Nice!

Get some pics up !

One thing I would do is install another USB port and connect it directly to the battery so you can use the battery to charge other 5V devices without having to connect the TF.
 

Bob Smith42

Senior Member
Jun 7, 2011
760
136
I removed the circuit board, now, and pulled back some of the covering tape.

I will post pics tomorrow. Sorry. I want good sunlight of circuit board stuff, because I think that is where we will need to attach the barrel plug charger wires.

The charging socket on the dock has 20 solder points and it looks like up to 3? power lines (visual inspection). With my sub-mm solder iron I can attach wires to charge via a plug. At some point we will need to know at least the power positions on the cable/plug, especially the grounds.

I think we can simply cut into the x2 red and 2x black battery lines for a switch, or aux power. There are total 8 lines on battery, exactly like the tablet, and about 4 inches of exposed wires.
 

Bob Smith42

Senior Member
Jun 7, 2011
760
136
Full list of photos:

Plug showing depth behind battery & rubber spacer (7mm depth; 5.0mm battery, 2.0mm rubber spacer):
2011-06-17_23-01-30_763.jpg

2011-06-17_23-01-24_494.jpg


Circuit board removed showing full hinge (back left):
2011-06-17_23-00-16_43.jpg


Full keyboard under side:
2011-06-17_20-57-33_910.jpg


Full bottom of dock with keyboard removed (large space between battery and back hinge):
2011-06-17_20-56-57_301.jpg


Closeup of back left hinge and charging port (4.75mm between circuit board and hinge metal, 8mm between circuit board and hex nut on hinge):
2011-06-17_20-56-12_778.jpg


Opposite to left hinge on keyboard side:
2011-06-17_20-56-02_106.jpg


Back left hinge and charging port:
2011-06-17_20-55-22_930.jpg


Keyboard under side (right half keyboard):
2011-06-17_20-54-45_964.jpg


Keyboard under side (middle keyboard):
2011-06-17_20-54-37_387.jpg


Keyboard under side (left half keyboard, side with power plug):
2011-06-17_20-54-27_760.jpg


Bottom of dock (middle):
2011-06-17_20-54-17_114.jpg


Bottom of dock (left):
2011-06-17_20-54-07_872.jpg


Bottom of dock (right):
2011-06-17_20-54-00_216.jpg


Bottom of dock (middle):
2011-06-17_20-53-35_692.jpg


Bottom of dock (left):
2011-06-17_20-53-18_225.jpg


Full keyboard underside with touch pad:
2011-06-17_20-53-08_67.jpg


Full bottom of dock with keyboard removed:
2011-06-17_20-53-00_830.jpg


Bottom of dock (left side, with power plug):
2011-06-17_20-52-40_582.jpg


Bottom of dock (right back side, with USB port, large space between battery and hinge):
2011-06-17_20-52-26_354.jpg


Bottom of dock (left back side, with power plug):
2011-06-17_20-52-17_476.jpg


Under side of keyboard:
2011-06-17_20-52-00_191.jpg


Bottom of dock, with keyboard removed:
2011-06-17_20-51-36_114.jpg
 
Last edited:

cowballz69

Senior Member
Jul 10, 2007
692
38
Can u try to see if u can follow the usb ports to the 40 pin connector to see what points are for usb connection? That way we can follow up to the tablet and install a usb port in the tablet. There is plenty of room for one inside it
 

mlbl

Senior Member
May 28, 2010
192
8
since the keyboard dock is opened, whats the battery rating in mah inside?
 

Bob Smith42

Senior Member
Jun 7, 2011
760
136
since the keyboard dock is opened, whats the battery rating in mah inside?

The battery says:
ASUS LI-polymer Battery Pack C21-EP101
Rating: +7.4V =~ 3300mAh, 24Wh

It is 5.0mm thick, 137mm long, 104mm wide. It is wrapped in a black plastic bag-like cover, and the length at top seems empty when pressed - so about 20mm at the top is just a cover and not *battery*. The battery inside is closer to 5mm x 117mm x 104mm. There are two 2.0mm thick rubber spacers on top of the battery, running the full length and 29mm wide each.
 
Last edited:

Bob Smith42

Senior Member
Jun 7, 2011
760
136
Can u try to see if u can follow the usb ports to the 40 pin connector to see what points are for usb connection? That way we can follow up to the tablet and install a usb port in the tablet. There is plenty of room for one inside it

I was able to use my fingers to easily slide out the battery plug on the circuit board. I will try to get some detailed photos of the circuit board today.

There are two groups of wires from the circuit board to the tablet plug. The silver colored is a shield and the black is unshielded. I was assuming the unshielded was USB, because USB lines do not *require* shielding - but, USB lines do require about 1 twist every 20mm or so. Also, I was assuming the shielded bits were keyboard & trackpad. But, I could be entirely wrong with these guesses.

One partial approach is to unplug both silver and black groups of wires and test continuity of each line from the tablet plug.

Tracing lines on the circuit board might be a good approach.

I was also going to test my cable, the USB end continuity against the 20 pin connector, and then plug in my cable to the port and test the matching solder points under the connector on the circuit board. Slightly safer now with battery removed.

Suggestions welcome as we go.
 

Bob Smith42

Senior Member
Jun 7, 2011
760
136
I am going to try something like this for the power jack: (See UPDATE below for correct component)

http://parts.digikey.com/1/parts/1052051-conn-pwr-jack-0-65x2-6mm-smt-pj-038-smt.html

IMAGE REMOVED (I suggest you do NOT use the component seen in link above)

I ordered a variety of jacks to test. The "DX-UA Universal" has a 0.7mm ID, 2.35mm OD - Plug tip. I noticed the Motorola 10.1 tablet has a similar power plug, but unsure of their voltage.

==
UPDATE: I do *not* like the socket listed above, because it has an open bottom (hard to glue in place) and it is *not* tall enough. It is too short so if the charging plug is pushed up and down the socket can be pried loose, no matter how good it is glued in place.

Rather I prefer this other component:
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=CP-031HPJCT-ND

MFG_PJ-031H-SMT.jpg


I reviewed about 10 various component models. The new choice, CP-031HPJCT-ND is:
(1) cheaper, shielded costs more and no benefit.
(2) taller, it fills the space between top and bottom of dock. Therefore, the screws holding the dock top/bottom together also hold it in place in addition to glue, e.g. it cannot be pried loose by impact on the charging plug.
(3) the hole is centered in the component, giving max strength to each side (other similar have a hole off center, which some might prefer but I do not, e.g. this CP1-022PJCT-ND is not as good in my opinion).

I will attempt to mount the preferred CP-031HPJCT-ND in the next few days, and advise of results. There are some mounting details that are required to successfully use these components, e.g. hole placement, electrical connection, positioning, etc..
 
Last edited:

dmc971989

Senior Member
Dec 17, 2009
528
7
guys... if we're already this in depth then why not just wire the power leads from the existing usb port in the dock over to the power/charging leads on the proprietary connector?


it would be far eaiser than adding a new connector/modding the case of the dock and would be even more "universal" since you could still charge with any usb adapter out there...
 

DevCake

Senior Member
Mar 3, 2008
468
62
guys... if we're already this in depth then why not just wire the power leads from the existing usb port in the dock over to the power/charging leads on the proprietary connector?


it would be far eaiser than adding a new connector/modding the case of the dock and would be even more "universal" since you could still charge with any usb adapter out there...

That's a good point but with some cons.

1. You still need to make or buy a cable to use an off the shelf universal charger.
2. That port will no longer supply power to any USB device you connect to it.

The main purpose of this mod is to be able to use almost any universal charger that is available so the extra work adding the new connector is worth it IMO.
 

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  • 4
    Full list of photos:

    Plug showing depth behind battery & rubber spacer (7mm depth; 5.0mm battery, 2.0mm rubber spacer):
    2011-06-17_23-01-30_763.jpg

    2011-06-17_23-01-24_494.jpg


    Circuit board removed showing full hinge (back left):
    2011-06-17_23-00-16_43.jpg


    Full keyboard under side:
    2011-06-17_20-57-33_910.jpg


    Full bottom of dock with keyboard removed (large space between battery and back hinge):
    2011-06-17_20-56-57_301.jpg


    Closeup of back left hinge and charging port (4.75mm between circuit board and hinge metal, 8mm between circuit board and hex nut on hinge):
    2011-06-17_20-56-12_778.jpg


    Opposite to left hinge on keyboard side:
    2011-06-17_20-56-02_106.jpg


    Back left hinge and charging port:
    2011-06-17_20-55-22_930.jpg


    Keyboard under side (right half keyboard):
    2011-06-17_20-54-45_964.jpg


    Keyboard under side (middle keyboard):
    2011-06-17_20-54-37_387.jpg


    Keyboard under side (left half keyboard, side with power plug):
    2011-06-17_20-54-27_760.jpg


    Bottom of dock (middle):
    2011-06-17_20-54-17_114.jpg


    Bottom of dock (left):
    2011-06-17_20-54-07_872.jpg


    Bottom of dock (right):
    2011-06-17_20-54-00_216.jpg


    Bottom of dock (middle):
    2011-06-17_20-53-35_692.jpg


    Bottom of dock (left):
    2011-06-17_20-53-18_225.jpg


    Full keyboard underside with touch pad:
    2011-06-17_20-53-08_67.jpg


    Full bottom of dock with keyboard removed:
    2011-06-17_20-53-00_830.jpg


    Bottom of dock (left side, with power plug):
    2011-06-17_20-52-40_582.jpg


    Bottom of dock (right back side, with USB port, large space between battery and hinge):
    2011-06-17_20-52-26_354.jpg


    Bottom of dock (left back side, with power plug):
    2011-06-17_20-52-17_476.jpg


    Under side of keyboard:
    2011-06-17_20-52-00_191.jpg


    Bottom of dock, with keyboard removed:
    2011-06-17_20-51-36_114.jpg
    1
    It is an excellent idea!

    But I'm thinking. If you can do this on the dock, couldn't you also do it on the TF itself?

    glg
    1
    Think I am going to try this mod. Ordered 2nd dock. If I go over-my-head I will contact DevCake for help.

    The issue with barrel plug on TF tablet is what to do when dock is attached?

    The advantage of barrel plug on dock is charging both dock and tablet, eliminating the need for any proprietary 40 pin cable (because doc has its own), and if you want to screw around the dock costs less (still $150USD is a lot, but less compared to a spare $40USD charger). Still need to consider what to do if barrel plug charging and something plugs into 40pin connector.

    I also plan to put in a slide switch to disconnect the dock battery from the tablet entirely to save juice when shut down. E.g. reports of doc losing power when attached. This could extend the stand-by life of the dock for a week or more.

    Once the thing is opened up, it might be a good time to discuss placements. Everyone has different and great ideas. I have a digital caliper to measure stuff.
    1
    Good news.

    I received my 2nd dock, and opened it. There are only two screws, under the rubber feet in the back by the hinge. These screws help support and hold the hinge in place. Run a plastic separator tool around the edge to open. I started in one back corner. It is tight in a few places. Do not bend the metal by the socket positions, where the metal is very thin and flexible. The front edge separates last (most difficult) using leverage of flapping open and closed the top/bottom pieces, and starting separation on one side.

    I will post pictures soon. I took some and in the process of uploading. I have my digital caliper at the other office so measurements later.

    There is a great position for a female socket for a barrel plug charger, behind the current charger and pointing to the back. It is between the hinge and a circuit board, so there is no leeway in width. The width is narrow, just under 5mm, so a socket needs to be thin. If we find a 4mm wide barrel socket, maybe 7mm or less high it should fit. Of course that makes a slim barrel. :)

    UPDATE: On further consideration, we might trim up to 3-4mm of the hinge plate, giving up to 7-8mm square barrel socket.

    The area between the battery (centered under the keyboard) and the back hinge is wide open. Literally room to drop in x4 sd cards end to end, and stack another row of x4 on top, with space left over. The entire space is about 5-10mm height. A switch can go anywhere in this area, mounted on the bottom face, which is protected by the protruding hinge.

    I was thinking with all the USB ports, it might be worth considering loading up some internal USB devices later.
    1
    Bob:

    I'm curious, is that a slide switch in the "Circuit board removed showing full hinge (back left)" photo between the main power connector and the track pad connector? If so are there any markings?

    Thanks,
    Mark