Question about cleaning keyboard membrane metal plate

[Dr Tiger Ninestein]

I've just opened up my 464 plus as a couple of keys are sticking when I press them. The rest work fine it's just two that stick for a couple of seconds before popping up.


I don't think I'm going to clean the actual membrane because all the keys register but the black metal plate that sits on the membrane is filthy. I've tried to lift it off so I can clean it without knocking all the crap onto the membrane but it doesn't move at all, is there something I need to do to release it?




Also the two pieces of copper that are coming from the board next to the ribbon cable, should they be touching the metal that houses the membrane?

[Kris]

You can use isopropylic alcohol to clean the metal shield, usually it works very well.

[Dr Tiger Ninestein]

Yeah that's what I'm using but I can't seem to lift the shield off of the membrane and I don't want to force it.


Should it just lift off?

[arnoldemu]

The black bit is plastic.

Turn the keyboard over to the metal and here there will either be lots of tiny screws or plastic tabs (most common) to push to release it. It will then lift off the membrane really easily.

[||C|-|E||]

Hum, I was adding some additional silver to my membrane a few days ago but sadly, I did not take pictures of how to disassemble it  . However, it you look at the keyboard from below, you will see that it has quite a lot of clips that go through the plate. Just push these gently and the metal plate will come off with no effort (or it should  ). About the copper from the motherboard, yes, it should be touching the metal plate. It is for grounding it.

@arnoldemu: oops, we replied at the same time! 

[Dr Tiger Ninestein]

Thanks guys, much appreciated.

[||C|-|E||]

The clips are not removed in the images of this post, because I treated the membrane without disassembling the keyboard, but you can see them there:

Keyboard problem in my Plus.

[Dr Tiger Ninestein]

Cheers. Great work on that btw

[Dr Tiger Ninestein]

Well I seem to have a bit of a problem now  


I cleaned everything up and put it back together but now when I turn it on there is a constant beep as if a key is held down. When I hit f1 and go into basic the Cursor moves across the screen until I press a button and then it stops.


Any idea what's happened?

[Dr Tiger Ninestein]

Absolutely gutted. I took the membrane out last night and washed it to see if I could fix the problem I created. I dried it over night and put it back in this morning and now all I get is this yellow screen when I turn it on



Edit. I'm a complete idiot, I was turning it on without the cart inserted .  I still have a constant beep when I turn it on though and when I go into basic the cursor still moves across the screen until I hit enter. That's after cleaning and washing the membrane.  Do I need to try a new membrane? Strange because it was working until I cleaned it.

[Bryce]

You've probably just mis-aligned the membrane, open it up again and check that it's correctly positioned.

Bryce.

[Dr Tiger Ninestein]

I've tried realigning the membrane but it seems to fit pretty snug, there isn't really any room for it to move about when you put it in position.


I don't get the beep when I turn on now and the cursor doesn't move but if I hit the spacebar it moves and doesn't stop. Also when I hit certain letters it will do a space as well as a letter. Another strange thing is when I touch the casing below the space bar the cursor moves.


There's obviously a problem withe the spacebar but I can't work out what or how to fix it.

[||C|-|E||]

It seems that something is triggering a couple of keys instead of one. I would say, as Bryce pointed, that the membrane is either misaligned or there is a tension in a particular region that causes the two layers to approach too much when you press the space bar. Since you realigned it, I would try to see how it behaves without the keyboard. Just let the membrane on the metal plate and check if everything works fine touching the position of the keys with a lot of care. If everything is OK, I would check that there is nothing in the keyboard itself that causes a double press.

[attachimg=1]

[Bryce]

Did you just clean the outer surfaces? Are you sure the there are no "pods" that are stuck down. possibly due to moisture between the layers?

If it beeps but doesn't put characters on the screen, it would point to it being the DEL key that's stuck. If the cursor is moving across the screen it's the spacebar kay that you need to look at.

Bryce.

Edit: Just read your last post properly: Have you mounted the complete keyboard properly in the CPC? It sounds like the case is pushing against the plastic of the spacebar.

[Dr Tiger Ninestein]

I've tried everything suggested now and still no luck although the cursor doesn't keep moving when I press space.


But whenever I press a letter in the two rows directly above the spacebar I get a space as well as a letter.


If I touch the amstrad logo below the space bar or any of the plastic casing in that area a space registers on the screen.


Bryce, it's a 464 plus and not a cpc464 if that makes a difference.


Edit: just checked again and all the rows of letters are causing a space to register as well as some of the number keys

[Bryce]

No, not really, but the fact that you get feedback when you press the logo would still point at the whole keyboard assembly being wrongly installed in the case.

Bryce.

[Dr Tiger Ninestein]

Im looking at it now and just can't see anything wrong with how it's sitting.


There is a hole in the membrane that part of the black plastic shield goes through that makes it sit in place so I don't think I can have got that wrong and then it's the same when you sit the whole thing into the casing. It has to sit in position so that the screws can go in.

[Bryce]

Does it happen when the top case cover isn't fitted?

Bryce.

[Dr Tiger Ninestein]

I just tried that and it's the same.


I've also just taken the membrane out and tried realigning its got worse. Not all the letters even register on the screen now.

[Dr Tiger Ninestein]

I've tried it without the keyboard sitting on the membrane and all the buttons on the membrane work fine. It seems to be when I attach the keyboard.

[Bryce]

Check that there is no dirt under the plastic or maybe a plastic tab that has bent or broke.

Bryce.

[Dr Tiger Ninestein]

I think I've solved the problem.


One of the springs on the space bar was bigger than the others. I must of stretched it by mistake.


I took a normal sized spring from another key and swapped it for the stretched one. Everything seems to be working fine now.


The problem now though is finding a replacement spring, does anywhere sell these?