I have a project that I have hit a wall on. I need your guidance!

Photo of Board I need to find the spots on the board for the 4 USB connections. The attached photo is of the board. There are 4 connections I need to find are: 5v+, data -, data +, ground It came out of an Apple MacBook Pro early 2008 A126C w/ bad mother board.

I've found instructions online for the models newer and older than mine on how to solder a USB cable to the controller board to use the keyboard and trackpad. I can't find anyone who has figured out the connections on mine. Can anyone help? I don't even know where to start... Is this even possible to do? I have searched the other topics but none had suggestions on how to find the connections.

Any thoughts or insight is welcome at this point!


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    \$\begingroup\$ Look at the chips datashits and trace traces \$\endgroup\$ – PlasmaHH Jul 16 '16 at 17:35
  • \$\begingroup\$ This may be one of those times where the situation is unique enough that a select few may know what you are talking about. For the rest of us, what is the overall goal here? FYI, unless Apples are very different, most laptops connect the keyboard to the mother board as a grid of switches. Not using USB. \$\endgroup\$ – st2000 Jul 16 '16 at 17:46
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    \$\begingroup\$ @st2000 Apple has used usb for keyboards and track pads for decades now. And so have most others. The major laptop brands do not use direct matrix connections. Keyboards and track pads were ps2 and now usb. Same for cameras and internal bluetooth, SD card readers, thumbprint readers, etc. Get with the times. \$\endgroup\$ – Passerby Jul 16 '16 at 22:53
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    \$\begingroup\$ @st2000 connection to the keyboard membrane itself I assume. This board will register the keypad button presses and transfer them to the PC via a USB-HID keyboard protocol. Some laptops have the control ICs on the motherboard, others will have them on the keyboard, it just depends on how the laptop was designed to fit together - half the time laptops will have several smaller PCBs dotted around with random combinations of stuff - like a DC jack and a USB port, or a touchpad controller and LED indicators. It's just however they fit everything into the small space. \$\endgroup\$ – Tom Carpenter Jul 17 '16 at 1:11
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    \$\begingroup\$ @st2000 let me rephrase, laptops rarely have a direct membrane matrix control interface. The controller tends to be usb to the motherboard. The membrane is still used, just not directly. \$\endgroup\$ – Passerby Jul 17 '16 at 2:08

The CY8C24794 has USB D+ on pin 20 and D- on pin 21. Tracks from these pins appear to go to the connector on the lower right. Here we also see a thick trace with a pad marked '5V0' which I am guessing is USB +5V. Ground is probably connected to the grid pattern on the PCB, so should be easy to meter out.

  • \$\begingroup\$ Ground is pprobably on most ccapacitors \$\endgroup\$ – Gregory Kornblum Jul 16 '16 at 17:52
  • \$\begingroup\$ @Bruce Abbott You are the Man!!! Thank you so much for answering the question in a way that not only showed me the answer but enabled me to do it on my own next time. One more question how did you know which of the chips was for USB? Thanks again! \$\endgroup\$ – Brian G. Jul 17 '16 at 15:15
  • \$\begingroup\$ I didn't 'know', but Cypress Semiconductor are well known for their USB chips. So when I saw that part number I figured it would be the one. Download datasheet, find USB pin numbers for that package, trace where they go, aha! \$\endgroup\$ – Bruce Abbott Jul 17 '16 at 18:24

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