Teardown—LG Cosmos VN250—Julia

I took apart an old cell phone with a QWERTY keyboard. It was surprisingly simple—only held together by a 14 little screws and glue. Here’s the process:

I used only these three tools (and my fingernails):

  • Phillips head screwdriver
  • Flat head screwdriver
  • Prying device

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The back of the phone came off easily, and each subsequent layer just had a couple of screws and some adhesive to get through. As far as I could tell, everything in this phone was metal or plastic.

  1. Take off the back of the phone.
  2. Remove battery.
  3. Unscrew screws in the back.
  4. Remove the plastic covers for charging connection, micro-usb, headphones on the sides and bottom.
  5. Pry off the plate which holds this plastic to the QWERTY keyboard and reveal the logic board.
  6. Take off the buttons on the sides (volume, power).
  7. The metal piece covering the middle of the logic board can be removed to reveal the Qualcom QSC6055 processor. More on the logic board below…
  8. Unscrew two more screws to reveal the QWERTY keypad and plastic piece underneath.
  9. The LCD/Numeric Keypad Cable threads through a hole in the black plastic beneath the logic board. Unscrew two more screws and pry off this black plastic.
  10. Underneath that black plastic are the data connections to the screen and the front keypad. Carefully peel off the tape that holds the connections down and unplug them. The screen will lift out. The keypad is behind the data board.

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GROUP SHOT!

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Now, more on the logic board:

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Here’s what I learned about all that a circuit board contains:

The circuit board holding microchips and processors inside a cell phone serves as the brains of the outfit. A digital signal processor, or DSP, converts an analog signal — your voice — to digital for transmission through the provider’s network. The DSP also converts a received digital signal to analog and moves the analog to the phone’s speaker and your ear. Radio frequency transmitters and receivers handle the signal as it moves to and from the phone. A microprocessor on the circuit board controls the phone’s various other functions, such as the keyboard and display. The phone’s operating system works from a memory chip, and the power management system keeps the device operating under battery power. A baseband chip serves as the phone’s antenna, grabbing and emitting digital signals when the phone is in use.

Here are all the parts I could identify:

  • Qualcomm CPU QSC6055
  • Micro SD slot
  • 1.2 Megapixel camera
  • Speaker
  • Audio jack
  • 3.7V Lithium-Ion Polymer Battery
  • LCD screen
  • QWERTY and regular keypad
  • ZIF connectors
  • Glued down cable ribbons

I couldn’t identify all the parts, but I did marvel at how simple the complex circuitry appeared.

I think the ribbon cable connectors are so elegant. It keeps everything very organized and clean (and flat), but the connections are very strong. I like the contradiction of these paper thin connectors and the power that is supplied through them. I’m always surprised by how sturdy and functional the connections are, especially on ZIF connectors.

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Back of the screen with plastic covered connector tape

I am also intrigued by the pressure sensors that are beneath all of the buttons. They are so sturdy, and the keyboard itself can withstand a lot of damage before the sensors beneath are affected.

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The layers of the QWERTY keyboard: slider, cover, letters, sensors