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AuthorTopic: Key "9" on my Amiga 500 keyboard doesn't work, took pictures and wanna know why.  (Read 156 times)

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Offline Ironclaw

So, nr 9 didn't work, no matter how hard I pressed, so I thought maybe the membrane had a broken connection somewhere, but used some tweezers (while wearing a rubber glove ofc, just in case) and noticed there's nothing wrong with the membrane as 9 registers when the tweezers touches them. So, I looked at the rubber thingy inside/under the key and cleaned it with some IPA and it still wouldn't work. I pushed it against other keys and none would register with nr 9's rubber thingy. So I took out a rubber thingy from another key and used it on nr 9 on the membrane and it worked. So, there's something wrong with 9's rubber thingy.

Only difference I can see between key 9's rubber thingy and other other keys is it's faded in color. I see no breakage or anything else. The tips might be a bit worn out maybe.

So, if they are faded they don't work?

9 is more important than the key to the left (see image), so swapped the rubber thingy with that one. So 9 works now, but ofc not that other key, which is OK.

Could only attach one image, so uploaded them to imgur: https://imgur.com/a/I28Z0Xl. Attached one image for those who don't wanna click links and still see something.
 

Offline Munchkin

You have to be careful when cleaning the keyboard plungers. There's a thin layer of conductive coating on them that wears off very easily with anything stronger than water and a tiny amount of soap. You can easilt rub it off as well if you're to persistent.

Might be possible to fix if you add some kind of conductive layer to them again, but it has to be very thin or else it might touch the membrane at all times. Electrically conductive glue perhaps?
 

Offline Ironclaw

Ah, so the plungers have a conductive coating on them. That would explain why this one didn't work, it's worn off.

I checked some A500 keyboard repair videos before looking inside the keyboard, and only warning I got was not to use IPA on the membrane. Luckily I only rubbed a bit on the tip/edge of each side (the parts that touch the membrane), not the whole thing of the broken plunger, which was already not working anyway.

Still wonder why that one and not any of the others is so worn out, and the color is faded, while all the others are bright and nice and work.

So, need to get a new plunger then I guess (won't go through the trouble of recoating it myself), if I want the other key to work as well. But, ithat one is not that important anyway.

The guy I bought the Amiga from said everything were tested and working before it was shipped to me, even every key. So guess he forgot to check that key.



Edit: Ordered 3 new plastic bits with plungers on them from ebay. One for the broken key, one for F3 which works but have to press really hard, and one more in case I might need it in the future.
« Last Edit: July 11, 2020, 10:25:10 PM by Ironclaw »