Teardowns I've Worked On

Answers

  • Answer to: Use of external mic thru audio jack

    The Nexus 7 has a normal 3-pole headphone-only jack at the bottom, and two microphones: one on the top left (on a little daughterboard plugged into the mainboard) and one on the lower left edge (soldered directly to the mainboard) about 1" above the docking pins. I don't know why they chose to do that. It is possible to replace the jack with a 4-pole and reroute the top microphone through it so it behaves as you would expect, but it's not a simple hack and it requires a willingness to shred your warranty and the equipment & skill to work with small SMD parts and flex-cable. Also, physically fitting and securing a 4-pole jack will probably involve epoxy and a dremel in addition to soldering little jumper wires. The Realtek ALC5642 - the (micro|head)phone driver chip - has Echo Cancellation and Noise Suppression built-in; one potential issue is whether the boost gain on the microphones (which is software selectable when the chip is used in PCs) is fine the way it is set, or if it can be tweaked. I haven't yet l...

Notes

  • Nexus 7 Teardown

    The glass is definitely not Gorilla Glass, and it is uber thin... I bought a broken N7 to perform evil experiments on and took it all the way apart, it was easy to see why they bonded the glass to the digitizer to the LCD to the frame - they are all so thin that it wouldn't have survived, otherwise.

    The broken unit I bought had a cracked screen, so there was nothing to lose by tearing it apart. To get it all out of the plastic frame I was chipping away paper-thin pieces of glass and glue, and at the end I was using q-tips dipped in boiling water to scrub away the remaining glue. It *might* be possible to use heat to soften the glue and remove the whole display in one piece, but it is highly likely that the heat would cause more problems than it solved. If you only want to save the frame and don't care about the other bits, this might not be a problem.

    There are probably other solutions involving chemicals to dissolve the glue, but I have no experience doing so.

  • Nexus 7 Teardown

    heslopharrison:

    the four metal dots (often called "pogo pins", which are really the springy pins that interface with such dots) are not USB (more's the pity) but they are for a dock: for charging, and for attaching external speakers.

    You can read 5V & GND off the outer pins (which made it seem like USB was a possibility), the inner two don't appear to do anything at first... but if you temporarily ground the right speaker channel, that tells the chip a dock is connected and it starts sending stereo output on the inner two pins.

  • Nexus 7 Teardown

    A few days ago some slides from ASUS were leaked. (The original post is down but posts are still up at slashgear.com and pocketables.com.) They show a leather case, a new charger, and a dock that uses the pogo pins on the side of the Nexus. The dock has a micro USB connector for charging/connectivity and a 3.5mm line out jack for external speakers or connecting to a stereo.

    Given that it is quite easy to pull data through USB (I have a USB 7.1 surround-sound adapter), this makes me think the pogo pins really are just a USB port.

    The articles also mention that there is no HDMI output because including it would have driven the manufacturing cost too high. The only way you are going to get HDMI out of a Nexus is if someone starts selling the equivalent of the full-width I/O Cable Assembly that was in the white Google I/O units (with the HDMI chip on it). The good news is that the yellow cables are identical, so the signal is present at that end, but nobody has released 3rd-party hardware that can use it.

  • Nexus 7 Teardown

    Those pins are for (future) docks, and possibly other accessories. (Keyboard-in-a-case, perhaps.) Google hasn't said what they are yet, and I haven't checked them out enough to know for sure, but it looks like the outer pins are power and ground (which makes sense for docks that charge) so I wouldn't be surprised if they turn out to be USB.

    The HDMI ports you speak of (on the Nexi from Google I/O) were on the bottom, the other side of the USB port from the headphone jack. In the pics you can see the space in the frame where it goes (under the speaker assembly). Those units had a different I/O cable assembly (Step 10, image 3) that went all the way across.