ADB Keyboard Repair

[Syntho]

One of my ADB keyboards is having an issue. It turns on the machine when plugged in. When I shut down the computer, it immediately turns back on as if it's a restart. I switched it out for another ADB keyboard and the problem is gone.

What could I do to repair it? Maybe take it apart and inspect the power button?

[GaryN]

It's just as likely or even more so that there's a short in the cable. Does it have a plug on both ends? If so, try a different ADB cord. Otherwise you get to open up the keyboard.

[Syntho]

I'm positive it's the keyboard. Switching out for another keyboard solved the problem. I think I may have to open her up.

[Syntho]

Calling all ADB nerds. We have an Apple Extended II keyboard that needs emergency surgery. Not sure how to go about fixing it but it always turns the power on on any computer I hook it to.

[FdB]

If the cable checks out okay (as per Gary, above)
and it does the same with different cable in place...
time to suspect the on-keyboard switch.

You can try the extreme alcohol / DeoxIt douche
or disassemble, check and then clean the switch.

Lots o' years and possibly accumulated grime inside.

Some-thing is completing that circuit.

Could just be stuck inside.

[Syntho]

I've ruled out the cable. I'm going to take a closer look, but upon first glance after opening it up, it looks perfect in there.

[FdB]

Well it’s a momentary switch, is it not? (Much like the front case power button.)

So either the switch is somehow in a constant-closed (on) state or there’s a short in the wiring (either internally in the keyboard or in the keyboard’s cable / connectors). If the switch proves to be bad or “constantly closed” you could clip one wire to the switch and test to see if it still auto-on powers up. If not, then either replace the switch or use the Mac’s front case power button? If it still powers up after the wire clip, then the problem is elsewhere. (internal wiring, kybd ADB connectors, etc.)

And of course you could check for continuity across the switch terminals, while in its’ not-on state.

Registers continuity?
Then clip a wire and test again.
Should tell you if switch is bad or short / grounded elsewhere completing the circuit.

[Syntho]

I've never tried Deoxit on a keyboard, but last night I told myself that if the thing is just gonna sit around and not be used, I might as well try something. So I broke out my Deoxit, sprayed it, hit the key 3,000 times, and... it hasn't turned on the machine all night, so far. I'm going to keep it plugged in and hope it works now.

Also, something I discovered when I took off the top is that there is some kind of oil ALL OVER the inside of the keyboard. It's odorless and clear. The date on the back of this keyboard says 1989 but I'm unsure if that's when it was manufactured, but somewhere down the line someone spilled or sprayed something on the inside of this. It works fine though.

Going to keep my fingers crossed for now.