Amiga 500 keyboard problem

[lopos2000]

Hi there,
just tested my A500 and it seems there is a problem with the keyboard.
Some key aren't working at all.
The second row (A to #) isn't working. Numeric keypad isn't working.
Also all Amiga ,Shift, CTRL aren't working. Swap the CIA chips. No different.
Any ideas.
TIA

Probably dead. They die like that and I've never heard of any A500 keyboard recovering after this point.

[BippyM]

The controller on the keyboard is most likely dead!

This was a common occurance with 500s.. check the caps-lock light.. it usually flashes in a sequence..this will give a clue as to what is wrong!

[lopos2000]

Caps-Lock doesn't work. No light at all.

On the bright side, now you have a set of spare keys.

[lopos2000]

Looks that way. Cleaned the whole keyboard and all the keys but still no luck. Damn it.

[BippyM]

The ribbon might be frayed/damaged.. this was a common accurance too unfortunately

[lopos2000]

I took out the 3.5'' drive and underneath i found some corroded IC's (U34 ,U15, U42) and parts. Must be that. That's what you get if you buy from eBay. I am taking it apart and sell of what is still working. The starnge thing is it still started up alright. Everything was working fine accept the keyboard.
Anyhow, thanks for all the help.

[Jope]

Corroded ICs on the motherboard will not affect missing rows / columns on the keyboard.

The keyboard talks to the motherboard via a serial protocol. Either you get keycodes or you don't but it won't receive some and not receive others.

This problem is in your keyboard.

1) the membrane <-> controller board connection is intermittent or broken for some signals
2) the membrane itself has some corroded or short circuited lines
3) there are broken solder joints in the controller board

So.. We'll start with the easiest.

Inspect the solder joints in the controller board. Reheat them with a soldering iron if unsure (perhaps add a small tiny bit of fresh solder to the joints). Test the keyboard.

If it didn't start working, then you need to open up the keyboard itself.

Take out all the small screws, have a small bowl or container next to your workspace where you can put them so you don't lose any.

Remove the black plastic keyboard mechanism.

Take a look at the membrane. Do you see any thin breaks in the silver conductor? Open the connector where the membrane connects to the controller board, are any of the contacts corroded or broken? Has there been a liquid spill? You can try to clean that off with a moist piece of kitchen paper.

You can try to blacken the broken conductors with a soft pencil, but be careful not to make things worse by using a too sharp point. Also silver paint works nicely (the stuff you use to repair car back window defrosters).

Be extra careful if you attempt any repairs in the area that plugs into the connector of the controller board.

If you happen to make things worse, don't worry - there are plenty of A500 keyboards in this world you can buy to replace the one you've got.

[lopos2000]

If have cleaned the keyboard with no luck at all. The membrane was a bit sticky so i cleaned it with conatct spray. Cleaned all keys and contact. But still no luck. I will have a look if I find a dry contact on the IC itself.
Thanks for the help

[Seblington]

I will take a trip into my loft shortly, its where most of my Amiga bits lay, if I come across a keyboard I will give you a shout, it would probably cost about £5 to ship if you want it, unless you already have a spare?

[lopos2000]

@seblington
Thanks for the offer. I got already a spare one.

[BippyM]

http://amiga.emugaming.com/selftest.html

Thanks to THB for finding and emugaming for hosting

I'm gonna put this in a post in the Hardware section and make it sticky anyway