Fix a 1200 keyboard with a 500 keyboard

[Piru]

@magistral

You can repair A1200 keyboard with A500 one, the only problem is that A500 keys are much darker.

If you decide to do this, you need to disassemble the keyboard completely (unscrew every small screw on the backside). Once the keyboard is open, you can remove the bottom metal plate. Under you can see the keyboard matrix.

If the keys are broken, just take the topside (keys) from the A500, use the matrix and bottom from the A1200 keyboard. This way you get the correct ribbon cable.

Here you can see external A1200 keyboard constructed of the A1200 case, A1200 keys and A500 keyboard matrix and metal bottom:

http://www.iki.fi/sintonen/tmp/keyb_front_1_s.jpg
http://www.iki.fi/sintonen/tmp/keyb_back_s.jpg
(If you look carefully you can see the dent on the metal bottom made by the stand holding the keyboard in place in A500 :-))

[Piru]

If the matrix itself (the film kind of thing) is damaged then you need to get a replacement one from a A1200 keyboard, or get a new keyboard altogether. The matrix itself is fragile and afaik quite impossible to fix.

I'd still check if the matrix is just dirty or if the buttons themselves are somehow damaged.

[Piru]

The signals are the same. The encoding is the same.

In fact A1200 mobo has the keyboard MPU on it directly, and at least I had to disconnect it (cut 2 pins) for the external keyboard to work correctly.