XO Troubleshooting Keyboard

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HowTo [ID# 179110]  +/-

This is the portion of the XO Troubleshooting Guide for diagnosing problems with the keyboard and touchpad of an XO laptop.

Does the keyboard seem unresponsive ?

When some keys are pressed on the keyboard, the laptop doesn't see them. Or the keyboard may appear completely non-functional, sometimes alternating with periods of correct operation.

The touchpad doesn't work either

If both the touchpad and keyboard don't work, then it is likely to be the connection between the keyboard controller and the motherboard (rare), or the keyboard controller. It might be the motherboard, although this has yet to be seen.

Disassemble both the top and the bottom of the laptop. Check the cabling between the motherboard (CN23) and the keyboard controller using an ohmmeter. Unlike the battery cable, there are no hidden connectors in this cable.

If the cable is fine, replace the keyboard controller with a known good one.

If the problem persists, replace the motherboard.

Suspect components on the motherboard include L37 (ferrite supplying 3.3V to the keyboard controller) and the anti-static protection chip U66.

Do you have a stuck modifier key ?

If the touchpad works, the keyboard problems may be due to a stuck modifier key ('CTRL', or 'ALT') in the keyboard.

To test for a stuck 'CTRL' or 'ALT' key, open the Terminal activity. Press the 'F' key. If you have a stuck 'ALT' key, pressing the 'F' key will bring up the frame (and make it go away). Alternatively, pressing the 'N' key will bring up the Journal. If nothing happens, press the 'L' key. If you have a stuck 'CTRL' key, pressing 'L' will clear the screen (in the Terminal activity). You can use the keyboard portion of the self-test to verify that the keyboard has stuck keys. Stuck keys are frequently intermittent (they will work fine for a while, then fail.)

If the keyboard has stuck keys, the solution is to replace the keyboard. This was a manufacturing problem (Trac ticket #5658) and has been fixed in newer laptops.

Checking the keyboard cabling

If the keyboard doesn't appear to have stuck keys, you should check the connector (CN23 on the motherboard).

Disassemble both the top and the bottom of the laptop. Check the cabling between the motherboard (CN23) and the keyboard controller using an ohmmeter. Unlike the battery cable, there are no hidden connectors in this cable.

If the cable appears fine, replace the keyboard controller with a known good one.

If the problem persists, replace the motherboard.

Suspect components on the motherboard include L3 and L5 (ferrites), R94 and R95 (10K), and the anti-static protection chip U66.

Does the keyboard generate unexpected responses ?

In this case, the keyboard generates key presses that the user didn't press. For example, a user may press the 'x' key and the laptop thinks that the 'x' key was pressed, followed by the 'c' key. Or a specific key may appear to be pressed intermittently, even when nothing is touching the keyboard.

It is possible that the problem is a loose cable between the keyboard and the keyboard controller. Disassemble the laptop and reseat the cable.

If this doesn't fix the problem, it is probably a "sticky key" on the keyboard, requiring a keyboard replacement.

Keys are tearing off the keyboard

Early production models have a keyboard which allows keys to be easily torn off (Trac ticket #1528). This has been improved in current production laptops. If you have a few torn keys on your XO, you can make a simple, inexpensive repair by following these instructions for a simple keyboard repair.

Is the touchpad unresponsive ?

This is possibly caused by loose cables between the touchpad and the keyboard controller.

If the keyboard is also non-functional, see above section on "keyboard and touchpad both broken".

It could also be the keyboard controller.

Does the touchpad only allow vertical (horizontal) movement ?

There was a fabrication problem which resulted in occasional laptop having a touchpad which only worked in a single direction (Trac ticket #5575). This has been fixed, but the same problem may still be seen occasionally.

The solution to this touchpad problem requires replacing the actual touchpad surface. Replacing just the touchpad surface is not recommended, as it is strongly glued down. Replace the entire bottom portion of the laptop, or at a minimum replace the touchpad and the piece to which it is glued.

Is the touchpad jerky or oversensitive ?

This may be a calibration problem, and some laptops are much more susceptible than others. G1G1 Users have anecdotally reported the following to help:

• Recalibrating the touchpad
• Rebooting the XO
• Upgrading to a later OS build
• Laying the XO on a flat surface
• Moving to a colder/warmer environment