Spem QL keyboard

[Chr$]

There is continuity between those pins on mine, too, so that's probably ok. Mine did work when I last checked (just not all keys).

Do you have 2x socketed HCF4066BE chips on the component side? I suppose you could re-socket them and check they are clean. There is a single electrolytic cap too, that you can also check. The rest is resistors and diodes. I just found another couple of cracked solder joints on mine.

[Delta]

Yes, I have those ICs which I have cleaned and reseated. I will replace the capacitor tomorrow.
I have noticed that all the keys show continuity between the top pin and bottom left. However, keys 5 & 6 on the numeric keypad show continuity between all three points. Is that correct behavior?

[Chr$]

With them not depressed? No, they shouldn't all be shorted if the key isn't pressed. Stuck keys could well be the issue I imagine. Remove those 2, see if it then works.

[Delta]

With them not depressed? No, they shouldn't all be shorted if the key isn't pressed. Stuck keys could well be the issue I imagine. Remove those 2, see if it then works.

Yes, with the keys not depressed. I realized I made a mistake. The top and bottom right (not bottom left) all show continuity but with those two, there is continuity between all three.

I will attempt to remove those two keys...

[Delta]

I have now removed a total of 6 keys that exhibited the strange behavior of showing continuity between all three points...Unfortunately, it has made no difference at all.

I am now considering removing them all and replacing them with better key switches.

[Delta]

They have a ribbon cable coming out of them with a long flat PCB at the other end that just plugs into the 2 k/b connectors on the QL motherboard. I have one and have replaced all the keyswitches with clicky ones (available new, brand Futaba).

Would you mind posting a link for the Futaba key switches you used?
Thanks

[Chr$]

These (clicky upgrade):

https://www.pollin.de/p/futaba-eingabet ... tch-420905

Or these if you want original non clicky:

https://www.pollin.de/p/futaba-eingabet ... f-n-421526

[Delta]

These (clicky upgrade):

https://www.pollin.de/p/futaba-eingabet ... tch-420905

Or these if you want original non clicky:

https://www.pollin.de/p/futaba-eingabet ... f-n-421526

Thank you.
I attempted to purchase and was told they don't ship to the UK
I will look for an alternative supplier.

[Chr$]

I can forward them on. I bought 100 (clicky) and also have 11 spares. Thought it would be a good idea to keep some spares as you never know how long they will be available. They were the only source I could find.

[Delta]

I can forward them on. I bought 100 (clicky) and also have 11 spares. Thought it would be a good idea to keep some spares as you never know how long they will be available. They were the only source I could find.

That's very kind of you, I was going to buy a 100 too so I can replace all the key switches.

However, I am not convinced my problem is the keyswitches as I tested them desoldered from the board and they worked as expected: a contact between the top and bottom right pin when depressed.