Video Cassette Takeapart

20-sept-06
This will guide you in what to look for when you take apart an ordinary T-120 VHS video cassette. As you proceed with your dissection, please keep the following in mind:
  1. Keep a good record of what you are doing in your sketchbook.
  2. Keep track of all the parts and update the bill of materials as you go along.
  3. Be as specific as you can with function and material.
  4. Make sure you understand how the internal parts work.
  5. If you have dial or digital calipers, measure the parts as you go along and record key dimensions in your notebook

Here we go:

Examine the door on the front of the tape. Can you find the release catch? How does it work?

Try to turn the tape spools by spinning the white parts on the underside of the tape with your thumb. Do they spin? Can you find the latch which when pushed lets the spools spin? Why is there a lock?

Find the screws which hold the case together. Undo the screws. Are they all the same length? What type are they?

Put the tape on its back (windows up) and carefully separate the "clamshell" case. (It's called a clamshell because it is in two halves). Try not to let things drop out.

Examine the lid (the top half which doesn't have the spools).

Now examine the base which has the spools still in place. Don't tip or else the spools will drop out!

Now remove the spools and place on the table in front of you in the same position that they were in the base.

Now for the fun part. How long is the tape in feet? Develop a plan for measuring, then do it. Record your answer in feet. Estimate the speed (in inches per second and miles per hour) of the tape when recording or playing back in standard play mode. Although you might find the length of the tape printed right on the box, as an engineer, you are obligated to not take printed specifications at face value and to develop and report on your own direct method for measuring the tape. Feel free, however, to compare your data with what is printed on the box and explain which one you think is closest to the actual length. And, don't automatically assume the box number is closer!

Challenge: Put the cassette back together (except for the tape).


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