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Fixit 29. Check for Device and Connectio... > ADB: Keyboard and Mouse/Trackball/Tr...

ADB: Keyboard and Mouse/Trackball/TrackPad

This section covers problems with the ADB port and the common devices (mouse and keyboard) connected to this port. This is mainly for the benefit of those users with older Macs that still have these ports. Some of the information, such as for cleaning a mouse, may also apply to USB versions of these devices.

Keyboard cable If you are having problems with your keyboard, check the cable before you assume it is a hardware problem with the keyboard itself. To do this, try using a different cable (assuming you have one). If the problem disappears when you switch cables, simply replace your original cable with a new one.

ADB ports Many models of Macintosh have two ADB ports. One, but not the other, may be defective. Try switching cables to see if only one port is associated with the problem. If so, you have a defective port. You need a repair.

Occasionally an ADB-related problem may be software-based, typically caused by a specific application that somehow conflicts with ADB port communication. Ideally, such applications come with special fixes (usually in the form of an extension, such as one called ADB Fix) that are used to get around this problem. Unfortunately, sometimes the presence of such extensions can be the cause of the problem. In this case, the simple solution is to discard the extension.

Defective keyboard or mouse If your keyboard seems dead but your mouse functions fine (or vice versa), switch the keyboard (or mouse) with one from another computer. If the second keyboard (or mouse) works fine on your computer, the original keyboard (or mouse) is probably defective. Usually these items are not repairable and need to be replaced.

A false freeze On many Macintosh models, you can choose to attach your mouse to either the ADB port on the rear of the Macintosh or the one on the side of the keyboard.

If you attach the mouse to the side of the keyboard, and the keyboard or keyboard cable is defective, then both the mouse and the keyboard cease to function. This may seem to resemble a system freeze (as described in Chapter 4). However, it is really a hardware problem. You can usually spot a false freeze because, with defective hardware, the cursor does not respond to the mouse even in the earliest stages of the startup sequence. In general, if the problem recurs no matter what software techniques you try, suspect a false freeze. Again, the simple solution is to replace the defective cable (or keyboard).

A false alarm (A beeping occurs whenever you press a key on the keyboard) If you hear a beeping sound whenever you hit a key on your keyboard and no character appears on your screen, you have turned on the Slow Keys feature of the Easy Access control panel. This is not a hardware problem. The character will appear if you hold down the key long enough. If the control panel is installed, this feature is turned on by holding down the Return key for more than 5 seconds. This control panel is designed for people with disabilities. Turning it off will fix the problem. Most other users should simply trash this control panel to avoid this problem in the future.

BY THE WAY — Are Individual Keys Defective?

Sometimes a problem with a keyboard is limited only to specific keys. A quick way to check for this is to use Apple's Key Caps desk accessory. Press the suspected defective key. If the matching screen image of the key darkens, then the key is okay. Conversely, if there is a key in the Key Caps display that is darkened before you press it, this is a stuck key. Depending on what key is stuck, this can cause a variety of different symptoms (imagine, for example, if the Mac thinks the Command key is always depressed!). This should work with both ADB and USB keyboards.

Cursor doesn't respond to mouse/trackball movements The inside of the mouse (or trackball), where the rubber ball lies, collects dust and dirt. Eventually, this may prevent the rollers inside the mouse/trackball from turning properly. The result is that the mouse/trackball responds intermittently, with jerky movements, or not at all. Fortunately, you can easily clean the inside of a mouse or trackball. Here's how:

Clean the mouse/trackball On most mice, press on the ring that surrounds the rubber ball and rotate it counterclockwise from its locked to open position. Turn over the mouse and let the ring and the ball fall out into your other hand. On some mouse models, the ring does not rotate; it slides out and snaps back in. In either case, once the mouse is open, blow briefly and strongly into the mouse to remove any loose dust. Use a cotton swab dipped in isopropyl alcohol to clean the rollers. Use tweezers, if necessary, to remove stuck-on dirt. Reverse the steps to reassemble the mouse, making sure the ball is dry and free of dirt.

Older PowerBooks have a trackball (the newer models use a TrackPad). As with the mouse, this ball also may need to be cleaned. To do so, turn the ring around the trackball counter clockwise until it pops out. Now you can lift out the ball.

TrackPad unresponsive or erratic For a TrackPad (as found on newer PowerBook models and on the iBook) that is unresponsive, try the following: 1) Put your PowerBook to sleep (by closing the display) and then wake it up (by pressing any key on the keyboard); 2) Press the PowerBook's reset button; 3) Zap the PRAM.

If the cursor is jumpy or erratic when you try to move it, make sure you are touching the TrackPad with just your finger (and not also your hand or wrist, for example). Similarly, make sure you are not accidentally touching the TrackPad as you are typing (a shareware utility called TapGuard can help avoid this). Also wipe off any moisture that may have collected on the TrackPad.

Numeric keypad doesn't work Some applications do not respond to numeric keypad input unless num lock is on. To turn it on, on most standard keyboards, press the num lock/clear button on the numeric keypad. The num lock light, above the keypad, should now come on. You should now be able to use the numeric keypad. Other programs do not respond to numeric keypad input no matter what you do. There is no fix for this.

USB If your keyboard and/or mouse are USB devices, ADB-specific tips will not apply. Check the previous section. Also note that certain Mac OS keyboard shortcuts (such as Command-Control-Power to restart your Mac) work with ADB keyboards but typically do not work with USB keyboards (as discussed in Chapter 4).



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