A500 keys not working
 

Hello,

Recently bought a Amiga 500 Rev 6A from a old friend.

I'm being trying to restore, but some issues come across.

Some keys, specially bottom keys are not working:

z,x,c,v,b,n,m, space, some cursor keys also.

I've already cleaned up the membrane, at first sight seems no track compromised, any opinions out there ?

thanks.

Regards.


Pedro

Check out ebay. https://www.ebay.com/itm/Connect-fav...kAAOSwT5xZOa-B
I bought this as a backup as my keyboard was bad when I bought my Amiga 500. I went and bought another membrane hoping that would fix the keyboard issues I was having. It did. But the membrane must have been bad as well. As it fixed some keys that didn't work before and it had other keys that didn't work. So then I bought a working keyboard off of ebay. But bought the circuit board as a backup. Works great with wireless keyboard.

You can purchase new keyboard membranes here:
https://www.sellmyretro.com/offer/de...Speed=noscript
A membrane can be faulty without having any visible signs, if in doubt it's best to replace it or exchange the faulty one for a working keyboard.

Quite expensive for a membrana.

Hi thanks for sharing, but I'm trying to keep my A500 most original as possible.

Don’t forget the down button, question mark, period, and comma.
Anyway you have to trace continuity from the keyboard membrane back to pin 32 of the keyboard controller.

Hi, thanks for Your reply, can you Share which PIN is that One on a picture? Thanks in advance.

Hi Does anyone knows where is the pin 32 on the keyboard controller ?


thanks

When you look a the big chip on the back of the small keyboard controller PCB, the dot in the corner of the chip is pin 1, and you count pins counter-clockwise from there.

If any of those other keys I mentioned actually work, then the break in in the membrane in the same row between a working one, and the first non-working one (and not in the ribbon cable part or on the PCB).

I is this correct?



https://i.imgur.com/vQOkMuH.png


In order to perform continuity test must the motherboard connect be in place ?


I'm totally lost, any help will be much appreciated



Regards

Dot is the half moon dimple on the left hand side of the chip.

You start counting the pins above the letter T in Mitsumi towards the right. That is pin 1. To its right is 2 3 4 5 6 etc.

Once you reach the end of the chip (above where it says C12), you jump to the top right corner of the chip and continue counting from that pin towards the left.

Awesome thanks for the explanation, Ill test it later.


Regards

So I've tried to track from pin 32 to some keys that are not working, but nothing happens.


Then I've tried other working keys, and nothing happens too, what am I doing wrong ?


I'm trying to measure continuity from the pin to a set of a key.

https://i.imgur.com/QTRPpX3.jpg


With a multimeter I've put one cable to the pin and one to one of the set of key.


https://i.imgur.com/oj7JTDe.jpg

Anyone??

I really don't get what kind of help you now need..

Look at how the traces go, follow the traces, identify the contact points along that trace, measure each part of the trace between the two nearest contact points, find the broken part and fix it.