Extended Keyboard II troubleshooting

[Cicero]

First time posting here. 

I recently acquired an SE/30. Advertised as computer and mouse  work, but keyboard does not work. Unsurprisingly with old computers shipped in the summer heat, the computer wasn’t working by the time it arrived on my front porch. I did I a full recap and cleaning of the logic board and got it up and running again. 

As advertised, the mouse works but the Apple Extended Keyboard II does not. I disassembled the keyboard and gave it a thorough cleaning and retrobrite treatment. After giving the keyboard main board an alcohol bath and drying it with a hair dryer, it started working again. But after sitting for a couple days, it now no longer works. The three LEDs light up briefly when it is plugged in. The ADB Mouse II works when plugged directly into either of the ADB ports on the computer, however it will not work when plugged into the keyboard.  I’ve reflowed the solder on the ADB connectors on the keyboard with no change in function.  I’ve confirmed continuity both on the ADB cable itself and between the ADB connectors of the keyboard. I currently do not have access to a confirmed working keyboard (ordered one that should arrive next week) or another Mac with ADB ports. Since the mouse works, I’m assuming the problem is not with the logic board.

Any suggestions for further troubleshooting this keyboard?  

 

[davidg5678]

While doing research about ADB to fix my SE/30, I found a very useful ADB keyboard troubleshooting section in the book "Troubleshooting your Macintosh" by Douglass High. It is available on vintageapple.org. I would recommend trying all of the troubleshooting steps in the ADB chapter. (Be sure to verify the circuit on the SE/30 board itself.)

Inside the ADB port, only a single wire is transferring data from both the keyboard and mouse, so the keyboard should work when the mouse does. (At least as far as I can tell from the cryptic "Inside Macintosh" books.) Are you able to use the mouse when it is daisy-chained through the keyboard? Do the caps-lock key and LED work?

It is possible one of the ICs on the keyboard is not working correctly. Hopefully, the chips themselves are functional and the problem lies in how they are connected somewhere else in the circuit. Are you able to post some photos of the circuit boards inside the keyboard?

Good luck!

 

[Cicero]

Just got one reading the ADB section of the book.  Thanks for the referral.  It's very informative.  Based on everything he says, I'm convinced the problem is with my keyboard and not the logic board.  Mouse does not work when daisy chained.  The caps lock LED does not illuminate when the caps lock key is depressed.  The three LEDs come on momentarily at startup but then remain unresponsive.  The RF choke filter on the keyboard PCB has good connectivity.

I'm wondering if there's still some debris lodged under the metal casing that separates the key switches from the actual PCB.  You can't remove the metal casing without desoldering each and every key switch.  Apple was nice enough to make some of the main components accessible through those cutouts, but there's enough space between the metal casing and the PCB that it would be easy for stuff to get down there and cause a short.  It was incredibly grimy and gross when I first opened it up.  I'm going to try another alcohol bath, agitating the board vigorously to try and dislodge any residual garbage that might be in there.

 

[Cicero]

Well, how about that!  Alcohol bath and blow dryer revived it.  There must have been some residual gunk between that non-removable metal plate and the PCB underneath causing a short.  I really wish I could get under that plate and give the PCB a proper scrubbing.

 

[Cicero]

Some keys are not responding and others are intermittent.  This will definitely need more washing, I think.

 

[Cicero]

Aaaaand it's back to not working again.  I'm so glad I have another AEK II on the way.  The previous owner(s) must have poured a lot of Mt. Dew on this thing.  Maybe some day I'll get bored enough to use my Hakko desoldering gun on this thing and separate the PCB from all the key switches.  For now though, this thing is going into the garage.

 

[uyjulian]

For those keyboards, I remove each of the keys, get a tub of water, then shake the assembly around. It will get rid of most of the stuck hair and dust, but residue may remain on the assembly between the keys. In that case, I grab some paper towels and wipe around the keyswitches, and do another round of water to clean up the particles from the paper towels.

 

[Cicero]

I'll give it a few more tries.

 

[Crutch]

Did you try a little WD40 into the troublesome switches? Pena recommends that as I recall, anyway it’s worked for me. 

 

[Crutch]

EDIT: I meant “Pina”!

 

[cruff]

I really wish I could get under that plate and give the PCB a proper scrubbing.

Is it not sufficient to remove all of the keycaps then the plate?  It is a minor pain, but you should then be able to remove the metal plate and clean up some more.

 

[Cicero]

Larry Pina's books have been invaluable to me in restoring this computer.  However, the problem isn't just with a select few keys.  The keyboard just stops working altogether after a while.

I removed all the keycaps but the key switches are attached to the PCB through the metal plate.  I haven't been able to figure out a way to separate the metal plate without desoldering every key switch.

Here's a picture from one of the times I got it working.

 

[Cicero]

Turns out it was a combination of the ADB cable itself being somehow bad as well as a few non functioning key switches. I finally got another AEKII and it works fine. The old AEKII works with the beer cable but has a few non responsive key switches. I’ll despiser those individually and disassemble the switches to clean them out. During the early cleaning process, the right arrow key switch actually expelled some kind of goo when depressed. I shudder to imagine what kind of precious life the keyboard had.