keyboard problem

Hey yannni and Welcome to Apple Discussions,

my keypad will automatically type all keys from the same column

So try an external keyboard and if that's fine you have a bad keyboard.
If you look here:
http://tinyurl.com/5976g8
you can see how this could happen but it would require a short in the horizontal array.
Did any fluids leak into the keyboard area?
Richard

Hi!
I'm having a pretty similar problem to Yannni in that only a select few keys on my keyboard are not working - 4, R, F, V.
Everything else appears to be fine. An external keyboard works perfectly so I figure that I have somehow shorted a circuit on my keyboard membrane. Does anyone know how this could be fixed at home? Or am I pretty much stuck with having to get a new keyboard altogether?
Many thanks
Bonnie

Hey bfk and Welcome to Apple Discussions,
Technically you should start a new thread since your problem is actually the opposite of Yanni's.
That said:

only a select few keys on my keyboard are not working - 4, R, F, V.

So if you look at that site that I reference to Yannni, the actual picture of the membrane traces. You see there that 4, R, F, V are on the same vertical line and exit the keyboard through the flex cable to the logic board. If you're lucky you'll see a crack in the flex where it folds under itself. That's a common fault.
If you're not lucky it will be within the keyboard membrane itself but all is not lost. You'd have to have a massive amount of patience and skill but it can be repaired. So disassembly is here:
http://mij.oltrelinux.com/ibook/cleaning_keyboard/
and further down in this site you'll see the membrane:
http://geektechnique.org/index.php?id=160

so I figure that I have somehow shorted a circuit on my keyboard membrane.

So not a short but one of these traces will be open. If you reference the keyboard 4, R, F, V on the membrane you'll see a vertical trace that corresponds to those keys.
If you hold it up the light you'll see a crack or a corrodes area in this trace.
It might take an ohm or continuity meter to isolate the spot. Usually where a liquid has spilled and corroded the trace away. Coffee is particularly bad for doing this.

Does anyone know how this could be fixed at home?

So the repair can be done with rear window defroster repair paint or conductive paint from a specialty electronics supplier. Radio Shack carried this but haven't seen it lately.
Richard

HI yannni and Welcome to Apple Discussions ...

Log on using a different user account and see if your keyboard functions as it should. If it does, then the problem is most likely isolated to your user account.

Adding a new user account to your computer
You can create individual user accounts for each person who uses your computer. Each new user has a separate home folder and can adjust his or her own preferences without affecting other users.

If you haven't created a user account besides your admin account, follow the instructions below:

Choose Apple menu > System Preferences and click Accounts.
If some settings are dimmed, click the lock icon and type an administrator name and password.
Click Add + and type the user's name.
If you don't want to use the short name generated automatically, type a new short name. (Once the account is created, you won't be able to change the short name.)
Type the user's password in the Password and Verify boxes.
Type a hint to help the user remember the password if they have trouble remembering it at login.
Click Parental Controls and select options to determine what the user can do with the computer.
If you change your mind while you're creating a new user account, click Delete - to cancel.

--- I keep one account named, "Test" ... just for this reason for troubleshooting.

Carolyn 🙂