Fixing an Apple Extended Keyboard II with a few dead keys ?

[Renegade]

So I have what I thought was a new-old-stock-but-unpacked AEK II with a Brtitish ISO layout.
It was sittiing in its original box, in mint condition: no yellowing and amazing untouched ALPS keycap feeling.

My intend was to swap the british keycap with the best looking (unyellowed) Belgian/French keycap I had.
Before going that hassle, it was wise to test it...

Upon a quick test, I noticed that the following keys do not work: F1, 1, Q, S and Z.

Looking at the PCB, the only weird stuff I encounter is this funny looking trace:



Could this be the cause of these non-working keys?

 

[davidg5678]

Do you have a multimeter with a continuity test feature? You can verify that this trace isn't broken by testing it with multimeter probes touching from one end of the trace to the other side.

It is also possible to get dust inside the mechanical keyboard switches, so I'd also try cleaning them out with a contact cleaner spray or isopropyl alcohol.

If this trace is indeed broken, and it is part of the keyboard matrix, (I can't tell without more circuit board pictures from further away) it is very likely to be the cause of the issues you are having.

 

[Renegade]

Do you have a multimeter with a continuity test feature? You can verify that this trace isn't broken by testing it with multimeter probes touching from one end of the trace to the other side.

It is also possible to get dust inside the mechanical keyboard switches, so I'd also try cleaning them out with a contact cleaner spray or isopropyl alcohol.

Thanks for the tip. Sadly my multimeter is at a remote relocation at the moment, so I won't be able to test for continuity before next week.

As for dust, it's very unlikely since the keyboard was stored in good condition in its original box. There is not the slightest trace of use (i.e. the black plate behind the PCB is perfectly clean) and it still emits the solvent smell of the new Apple products from that time.

If this trace is indeed broken, and it is part of the keyboard matrix, (I can't tell without more circuit board pictures from further away) it is very likely to be the cause of the issues you are having.

I'll try to post a picture of the whole PCB.

 

[Renegade]

A picture of the whole PCB :

 

[CircuitBored]

Dust is not the issue with these switches, it's the oxidation of the contacts inside.

Buy some contact cleaner (I use the WD-40 brand but any non-conductive variety should do the trick), remove the caps from the dead switches, spray a generous amount of contact cleaner into the switch around the stem, and then rapidly, vigorously press the switch over and over again. I use the rubber end of a pencil to allow me to do it faster and more comfortably. It may take well over fifty depressions to clean them up but I can almost guarantee that it will work. I have done this procedure on about half a dozen vintage Alps-based keyboards and it has never failed me.

You will likely discover that there are a few intermittent keys when you come to actually using the keyboard.

If I were you I would fix up that dodgy trace just for peace of mind.

 

[shadedream]

This sounds like a trace (or diode) issue on the board rather than oxidized contacts since it's a column failure. Would definitely need a multimeter in continuity mode to track it down but shouldn't be too hard to find and is probably an easy fix with a bodge wire or fixing a diode.

Spraying contact cleaner into alps switches would be worrying to me long term. Yeah, it fixes the corrosion issue, but it's likely to clean off any remaining factory lubricant and the residue from it will attract dust making the switches gritty eventually. Alps switches are known for collecting dust and losing their smoothness over time.

If corrosion is the issue, I'd probably open the switch and clean the contacts directly (not that hard to do with an alps switch even while still soldered in the board).