IBM model M - some keys stopped working

[adi.hodos]

Hello everyone, I would like some advice. I have acquired an old IBM model M (1391406) - manufactured in the UK, in the year 1990. It worked perfectly until 3 days ago, when some keys refused to send any scan codes to the OS (k, 0, p), although they still make that clicky sound. So I have dismantled the keyboard and cleaned it up. There were traces of some sticky fluid spilled in it a long time ago (probably coffee) and some of the springs were a little bit rusty (the upper end). After cleaning it, I assembled it back, and it worked flawlessly for another 2 days. But now the same keys don't work anymore. Is there anything that can be done ? Could the connecting cable be faulty ? Or the springs ?
I will try to upload some photos that I took in the cleaning process.

[wellington1869]

If you're handy with a volt meter you could check the connections on the motherboard. On the other hand, a replacement will cost only about 20 to 30 bucks on ebay.

[kishy]

a replacement will cost only about 20 to 30 bucks on ebay.

Or, you know, here on geekhack...

[adi.hodos]

Well I don't think that the cable or the motherboard connectors are at fault here, since only some keys do not work (k, -, 0, p). And it's random, now it's working, I'm typing at it and all the keys are ok. This is very strange... Could it be the fact that the springs have a little rust at their upper end ? If so, is it possible to replace the springs ?

[timw4mail]

Could it be the fact that the springs have a little rust at their upper end ?

That's unlikely to matter, because the mechanism is not capacitive.

I believe Unicomp refurbishes Model Ms at a decent price.

[kishy]

A question: how long does it take these problems to surface?

Do you keep your computer on all day, every day without shutting down at night?

My suspicion, if this takes a while to happen and the computer is on for ages at a time, would be that there may be a power issue of some kind which only surfaces after having the keyboard (known to be a power hungry one) powered up for a long time.

[ch_123]

That's unlikely to matter, because the mechanism is not capacitive.

Wouldn't matter either way... in the capacitive mechanism, the hammer is made out of conductive plastic, so it's not going to rust.

[microsoft windows]

A question: how long does it take these problems to surface?

Do you keep your computer on all day, every day without shutting down at night?

My suspicion, if this takes a while to happen and the computer is on for ages at a time, would be that there may be a power issue of some kind which only surfaces after having the keyboard (known to be a power hungry one) powered up for a long time.

I've got a computer with an M5-2 and it's been on for a few months. No problems.

Power issues with keyboards tend to happen when you start the computer.

[adi.hodos]

Sometimes it works for a period after booting the computer. Other times it simply refuses to send those keystrokes from booting until shutdown.

[timw4mail]

Sometimes it works for a period after booting the computer. Other times it simply refuses to send those keystrokes from booting until shutdown.

I assume you have it hooked up via PS/2? If so, you should try and see if a USB adapter will work.

[adi.hodos]

Yes, it's hooked via PS2. My motherboard is a MSI P35-Neo2. I'll try to find a PS2 to USB adapter.