date 10/18/2013

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Summary:         

• In order to measure the resistance and capacitance from the circuit base more effectively and to draw a scheme by using kicad, I remove the circuit base from the socket by unsoldering each pin that attacthed to the circuit board.

Initial condition of the base and socket:

• see the attached base.pdf (by Professor Heppelmann) for its status before this process.
• no further major change from the status described on the pdf.

Materials used:

• Solder iron (about 300 celcius to 400 celcius when it is heated up).
• copper braid (to absord the solder after they melted)
• Chipquik tack flux ( help the melted solder to flow to the copper braid)
• 91% isopropyl alchohol (clean the flux residue on the circuit board with paintbrush afterward)
• tweezers (mostly to stablize the pin from the socket)
  
• pliers (change the orientation of the pins when try to take out the board)
  

Process details:

1. Apply a small amount of flux on one connection from the pin to the board.
2. After the solder iron is heat up, use it to touch the connection slightly, until the solder junction started to melt --- beware of the heat the melting the board itself, since the surface does not seem very heat-resisted.
3. Using the copper braid to absorb the solder, not necessarily clean up all of them, but at least enough to not let the pin entangling on the connection.
4. Since the solder liquid will be back to solid state in a few second, use the tweezer to push the pin to one side to prevent its contact to the circuit.
5. repeat the above process for each pin, though the one also with capacitor attached on it may consume a bit more time due to amount of solder and removing pins among wires.
6. however, since the pins are holding the circuit board like a claw holding a ball, it is unlikely to remove the circuit base from the socket without using the plier to move the tip of pins ----- further consequence need to be thought of.
7. Using alcolhol to clean the residue on the board.
   

Time consumption:
         about 20 ~25 minute for removing the circuit base ( about 12 pins attached needs to be work on), including 1~2 minute of cleaning the residue on the surface.
      // since this is the first attempt, so the time consumption may actually higher than average)
         *Oveall it is not considering a tough task, just require some time and concentration.

***************** Pictures taken by Professor Heppelmann, notice that the C4 capacitor is detached from the board just because it fall off during the desoldering process.*****************************

Post-test: the circuit board seems fine after the process ( I used a voltmeter to measure the resistance across the connections , the result numbers are still very closed to the measurement before doing
this dissembling work, and no further problems occur so far)

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Below is the scheme drawn by using the kicad, and pin name is corresponding to the name given on the attached base.pdf file.
note: The "connect1" pin is where the C4 capacitor ( the biggest capacitor on the board) is connected to the black cap.