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has a list of working <strong>SD</strong> cards. Buy from a reliable vendor as it has been claimed<br />
(http://www.petapixel.com/2011/05/20/one-third-of-the-sandisk-memory-cards-on-earthare-counterfeit/)<br />
that 1/3 of all "Sandisk" labelled memory cards are counterfeit.<br />
▪ It could be that the <strong>SD</strong> memory card is not making proper contact with the Raspberry<br />
Pi. Look at the <strong>SD</strong> card holder on the Raspberry Pi carefully. At first glance it may<br />
look fine but the contacts must be springy and they must protrude at least 2mm as<br />
measured fron the lower edge of the holder to the top of the contact bulge. This<br />
happens due to the solder process and the type of holder used. Some of the solder<br />
residue falls into the contact cavity restricting the springiness and the height that the<br />
contact protrudes. You can fix this yourself but remember you can void your<br />
warranty. The contacts are delicate so be carefull. Insert a needle pin under the<br />
contact bulge and pull lightly up until the one end of the contact unclips. Clean the<br />
cavity where the contact unclipped from of any solder or other residue by blowing<br />
into the cavity. Clip the contact back into the cavity by lightly pushing it into the<br />
cavity. Do this for all the contacts. Look at these photos. Media:<strong>SD</strong>cardHolder.JPG,<br />
Media:UnclipContact.JPG, Media:UnclippedContact.JPG<br />
Keyboard / Mouse / Input Devices<br />
R-Pi does not respond to key presses / Keyboard randomly repeats key<br />
presses<br />
note:during entering the password most linux distro's wont show that you typed in<br />
anything (not even "*" characters) this is normal behaviour, try the keyboard while<br />
entering the user name!<br />
This is most often caused by inadequate power. Use a good power supply and a good<br />
power cable. Some cheap cables that work with a cell phone, cannot fully power the R-Pi.<br />
Some USB devices require a lot of power: most will have a label showing the voltage and<br />
mA requirements. They should be 5v 100mA each max, any more than this they must be<br />
used with a powered USB hub. Try unplugging every USB device except the keyboard<br />
(you should also note that some keyboards have built in hubs and can try to draw 150mA<br />
(Pi can only handle 100mA per USB slot without a hub)). Also, use the latest software.<br />
Forum user MrEngman reported (http://www.raspberrypi.<strong>org</strong>/forum/absolute-beginners/<br />
using-a-powered-usb-port-to-power-a-rpi#p76485) some keyboard repeats and wireless<br />
hangs until upgrading (http://www.raspberrypi.<strong>org</strong>/downloads) to the<br />
debian6-19-04-2012 kernel, which he reports stable with no problems even with a low<br />
TP1-TP2 voltage of 4.65 - 4.68 volts.
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