When I was writing my TiVo hacking book, my favorite part of the entire project was taking apart two TiVos (a series 1 and series 2) and trying to figure out what everything did. I tested components, poked around inside the code, did countless Google searches on chip manufacturers and parts numbers, looked up patents, looked for clues in other books and on hacker discussion forums. It was fascinating detective work that was far more exciting and interesting than I expected.
EMS Labs recently retired a HP Color LaserJet 2600n. Windell whipped out his screwdriver and camera and documented the deconstruction of the beast, in search of knowledge about how the thing worked and usable parts. He took some 200 photos (all available on Flickr) and offers some fascinating insight into how the various printer components work. Here's an example:
Here is one surprising element from the optics package. This is a precision molded plastic lens assembly with three lenses. The lens on the left is a plain (near cylindrical) convex lens that focuses light onto the photodiode that we saw earlier. The other two lenses are for the beams coming from the laser diodes towards the rotating mirror. As you can see in the lens on the right, it's not an ordinary lens, but a cylindrical lens that has rulings on it-- probably a cylindrical fresnel lens. The rulings diffract light, however, so it's really something to look at.
And here are the parts he was able to toss into his technojunk box:
1. Machined metal scanning mirrors on high-speed brushless motor drives with aluminum circuit boards (2)
2. Infrared (?) laser diodes (4)
3. "Interesting" photodiodes. (2) ( My guess: position-sensitive types)
4. 12+ photodiode/photosensor pairs. 7+ standard photointerrupters, and others
5. One humidity sensor
6. Stepper motors (2)
7. 9" x 1/4" high-temperature thick-film ceramic heater
8. 2.5" x 3/8" first surface mirrors (4), presumably for IR
9. Precision molded plastic aspheric lenses (10)
10. Glass lenses (4)
11. An "outrunner" style brushless motor
12. Solenoids (3)
13. A microswitch with a long lever
14. Three microswitch buttons
15. Plastic gears -- dozens.
16. Garden-variety computer fan
17. High-voltage capacitors and transformers
18. Heat sinks
19. An LCD display
20. Precision ground shafts
21. A thermal cut-off fuse
22. Temperature sensors
23. Anti-backlash gears
24. Funny shaped cams
25. A giant pile of phillips head screws
26. Lots of wire in neat bundles
27. Other circuit boards filled with of interesting components
Epic take-apart: HP Color LaserJet 2600n