Enter Key on Numberpad not working

[geoff]

Hi All,

I recently replaced the membrane on my A1200 keyboard to fix some issues with some keys. This has fixed them all apart from enter on the numberpad. I have had the key off and can see no obvious issues. But still no luck. Has anyone else had anything similar?

Geoff.

[modrobert]

If possible, measure the resistance in the key conductive pad (the part touching the membrane when key is pressed) for the numeric enter using a multimeter, maybe too high resistance, compare with other key pads. You can find key insert with pad for A1200 sold on ebay.

Also worth inspecting the connector part of the membrane closely for damage and clean it with alcohol (isopropanol) for good connection.

You probably know this already, but just in case; the keyboard connector on the A1200 motherboard is a ZIF (Zero Insertion Force) socket, the top part of the connector needs to be gently pulled up before removing or inserting membrane connector, then pushed down to lock in place.

[Leon Besson]

Which membrane replacement did you buy?

This one; https://www.ebay.co.uk/itm/224192653...mis&media=COPY

Or this one; https://www.ebay.co.uk/itm/165579811...mis&media=COPY

I have bought and used the latter one as they are more hard wearing Bromigo!

[geoff]

Originally Posted by modrobert

If possible, measure the resistance in the key conductive pad (the part touching the membrane when key is pressed) for the numeric enter using a multimeter, maybe too high resistance, compare with other key pads. You can find key insert with pad for A1200 sold on ebay.

Also worth inspecting the connector part of the membrane closely for damage and clean it with alcohol (isopropanol) for good connection.

You probably know this already, but just in case; the keyboard connector on the A1200 motherboard is a ZIF (Zero Insertion Force) socket, the top part of the connector needs to be gently pulled up before removing or inserting membrane connector, then pushed down to lock in place.

Thanks for the feedback - I’ll give the multimeter a go

[geoff]

Originally Posted by Leon Besson

Which membrane replacement did you buy?

This one; https://www.ebay.co.uk/itm/224192653...mis&media=COPY

Or this one; https://www.ebay.co.uk/itm/165579811...mis&media=COPY

I have bought and used the latter one as they are more hard wearing Bromigo!

I’m on the later one too - it’s only the one key at least!

[Leon Besson]

There might be a way to use carbon paint? To fix the issue.

[solarmon]

Swap the plunger with another known working one.

If the issue moves with the plunger then it is that - you probably need to either replace it, or fix it (I use silver conductive paint, or copper tape cut to size).

[Jope]

Or wipe the rubber a few (3-5) times against a sheet of A4 (or letter) paper, clean off any paper dust and presto. Repeat if better but not perfect.

[Leon Besson]

Originally Posted by Jope

Or wipe the rubber a few (3-5) times against a sheet of A4 (or letter) paper, clean off any paper dust and presto. Repeat if better but not perfect.

Nice tip Jope Bromigo!

Have ordered some copper tape off EBay as well, as I’ve discovered after a membrane change some keys not working also.

[MrClump]

Originally Posted by solarmon

Swap the plunger with another known working one.

If the issue moves with the plunger then it is that - you probably need to either replace it, or fix it (I use silver conductive paint, or copper tape cut to size).

I’ve even got it to work with some aluminium foil pinched from the kitchen!