Date   : Wed, 23 Oct 2002 21:34:23 +1300
From   : Michael Foot <mjfoot@...>
Subject: BBC keyboard playing up

Hi all,

One of my BBC model B's has had an unusual fault with the keyboard recently.
On and off, some of the keys will just stop working. Often from switch on
the full keyboard will work, then after a while some of the keys will stop
being detected. These are keys such as Caps Lock, Shift Lock, Return, F0,
F1, F3, F4 and F5.
I have had a look at the keyboard diagram in the AUG and can confirm that
failing keys are all on columns 0, 1, 3, 4 and some others. 

I'm guessing that a contact is being lost somewhere due to the machine heating
up, but cannot find where this is.

Has anyone encounted this type of behavour before? What ICs control the signals
to/from the keyboard?

Thanks,

Mike.

-- 
Michael Foot <mjfoot(at)paradise(dot)net(dot)nz> *
http://homepages.paradise.net.nz/mjfoot/
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