fixing a faulty key
 

ok I did search. but this thread:
http://eab.abime.net/showthread.php?...=sticking+keys - ends too soon for any solution.

I only have 1 bad key I think, on my a500. It's the down arrow key. The one under Del/Help not the one which is also '2' (if you know what I mean)

I seriously need to get this key to work so I can play Pipe Mania properly lol.
Any idea what's causing it not to work? It jumps back up again (so that's ok). What cleaning should be done? I tried to lift the key but I didn't force it out because I didn't want to damage it... I guess there's contacts underneith.

Thanks for reading :)

Its most probably the membrane. Can never be too sure withot seeing it but ive had 2 cases where my AMIGA keyboard membrane has stopped working. You cant get a used repacement off ebay for about 3 pounds.

Actually it's most probably the rubber elastomer that's under the key stem.

Hi,

Bumping this thread.

I just tried to get my A1200 out of storage, and its going... SEMI fine.

Some keys are not working,

6, Y, H, N, 8 (Number pad), and F1 works when it wants to.

Are the suggestions in this thread still relevant ?

What is a likely fix?

I had similar problems with my keys on A2000. There are multiple keyboard designs and each can have different problem, but same sticky issue.
You need to take apart the keyboard and examine how does the key works. There can be a spring missing or out of place, or rubber tube is damaged, or key terminals bent. Take it apart don't be afraid. :nervous

I have similar problem with my A3000 keyboard, when multiple keys are not working there might be an open in one ground trace connecting these keys. In my keyboard, the L Shift, L CTRL, LALT and some other key was not working. I took it apart and with volt meter found an open on ground, I was not able to fix it because you need some liquid silver to paint new trace :sad, which I don't have (my keyboard was using plastic membrane).

You could have different problem like spilled juice or milk or beer, it just need some cleaning :blased.

FIXED IT..............

took the KB out, opened it up and reBlew out any crap I could find, sand, dust bunnies, whatever....

Cleaned the graphite pads with Isopropyl, put the KB back together, cleaned the Ribbon contacts......, Works a treat.

[edit] its happening again, with more keys doing it now.

Might be time for a new membrane :(

The fix is different for each type of keyboard technology.

I recently fixed my A500 which has plastic spacers inbetween two metal 'fingers', I found the best approach was isopropyl and a toothbrush. Membrane types is best with a coarser cloth like denim and isopropyl, clean everything really well.

on the a1200 keyboard it wears where you attach it to the motherboard, theres a simple fix involving cutting a bit off the end of the flat cable and cleaning the green stuff off.

do a search as theres a thread about it round here somewhere

Touch up the graphite pads with a soft pencil then brush off the excess dust. I used to repair a lot of older calculators with membrane keyboards using pencil graphite.

Noooo, just wipe the pads with normal copier paper until they're no longer shiny. The pencil makes a mess and doesn't last as long as getting rid of the burnish on the rubbers. :-)

If the pads are worn out, that won't work, Jope.... although conductive paint (the type used to repair PCB tracks) is quite good for this too.

Are we talking about the same pad? I mean the rubber.. It's about 3mm thick and the paper trick wears it down maybe hundredths of a millimeter. The pads on the membrane / pcb don't wear out nearly as much.

Erm, no... we aren't talking the same thing here, are we?

(/me shuts up)

Probably not.. If the black blobs on the membrane/pcb are somehow worn, then it's quite a difficult thing to fix those.

I have had a few where the previous repairman as replaced the blobs on a C-128 keyboard with some solder.. Wasn't a very good substitute.. :-) I guess conductive paint is among the best for that side of the problem. :-)

I thought so, because you can at least build layers of conductive paint up; that's quite a tough thing to do with solder without damaging the board.

What I do not get though, is if its the ribbon cable losing contact with the motherboard connector (Worn Graphite contacts), is why only SOME keys do not work, and the rest do ?

Here it is - Akira's A600/A1200 keyboard fix with pics! :)
http://eab.abime.net/showthread.php?t=51596

The keyboard is a matrix of horizontal and vertical lines that are connected together. If a vertical line stops making contact, all the keys that rely on that vertical line die.