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Resposta para "How do I remove worn out chain rings?"Do you mean the chain rings (front gears) or the freewheel cassette (rear gears)? The chain rings are pretty straightforward. Just remove the cranks (see the tutorial here), then undo the bolts holding the chainrings in place. They're usually hex bolts. For the rear cassette, you'll need some specialized tools, but they're not expensive. Once again, Park Tools has a good tutorial. I'm not affiliated with Park, but do own some of their products. They make very high-quality stuff and price it accordingly. If you're only doing the job once, you can find cheaper versions of the same tools. Drive train parts tend to be torqued on pretty tightly. Don't be afraid to apply some force to them, but do it carefully. Make sure the wrenches are seated firmly in place, and then jerk repeatedly on them to break things loose. Re-seat the wrenches if they start to drift free. It's the same principle as an impact wrench, but with muscle power instead of pneumatics.
Resposta para "Why does this mac keep going to sleep?"There's a switch in the hinge that tells the machine when the lid is down. When that switch closes, the machine goes into sleep mode. The Wallstreet dissipates a lot of its heat through the keyboard, so this is a self-preservation feature - running it with the lid down would fry the boards. If the switch is stuck (which could well be the case given the broken hinges), then there'd be a constant "lid is closed" signal, which would produce exactly this behavior. Disconnect the power, remove the battery, and carefully open the lower case to get to the hinges (I believe there's a teardown photo set for the Wallstreet around here somewhere). Locate the switch and check it with a multimeter to see if it's working. If it's stuck, you could just disconnect it and tell your little brother to avoid closing the lid or covering the keyboard.
Resposta para "Why can't I receive GPS position when in Plane Mode"Cell phone GPSs - and I assume the iPhone implements it the same way - aren't "real" GPS devices. A standalone GPS does two things: receives time codes from multiple satellites, then does a complex series of calculations to convert that information into a position fix. The signal reception part is easy; the calculations are computationally intensive. In order to conserve battery power and space, cell phones only do the first part. They receive the raw time code signals, then relay them to a server maintained by your phone company. The server crunches the numbers, figures out the cell phone's location, and relays that back to your phone. If you're not on the network, your cell phone's GPS won't work.