Help diagnose some AEKII issues!

[Johnnya101]

Hi guys,

Finally sorting through my small collection of keyboards, and will be starting to "refurbish" them, retrobrite, etc.

Ive got two AEK IIs. one works good, the other, not so much. 

When I plug it in, 80% of the time it does not type, BUT the mouse connected to it works great. Wiggling the plug does nothing. Changing the cable doesnt help. Sometimes plugging it in again will work for a few seconds. but when it IS working, it works good.

Im guessing that I need to open it up and look for breaks somewhere...? Is this a sign of something more than a broken solder joint?

Also, I noticed that on both AEKIIs, none of the lights at the top work. I am, however, only testing them with my Portable. Is it because they need something newer to "work"? Or are the LEDs burned out? Or...? They flashed (all at once) one time. I suppose Ill lug my G3 out again to test them.

Thanks for the help.

Edit

Took apart the one iffy keyboard. No obvious signs of damage yet...

 

[Johnnya101]

Did some more tests with my G3...

Good AEKII still has no lights at all. No function lights come on. Caps lock works, no light. I could not get num lock working on either keyboard, but Im sure its just that Im not using it right.

Bad AEKII has a very strange issue going on. Plugging it in has it working fine some of the time with no light on. If I kind of "punch" it hard with my finger, or slam it down, then the num lock light comes on, and I am not able to type or use the mouse. But as soon as I punch it a second time (Or tap it very hard, I suppose you could say), everything (Besides the lights) work again.

The bad one is half apart if it makes the "tapping" a little more clear. The board isnt fully sat it, so I can kind of tap it stuff since the cover isnt on.

So. Strange issues. No idea what I should do to start. Solder joints look good. Also looked into if previous (And my attempts) of hot swapping were to blame. It appears not, as that would break something on the computer side.

 

[Johnnya101]

On the bad one I noticed two joints touching each other that shouldn't have been. Pretty much no change. I noticed pressing down on the lower right of the num pad, the light goes off, then goes on if I let go. Broken trace?

 

[CC_333]

Hmm, can't explain the non-functioning lights.

As for the other weirdness, maybe it's a bad key switch or two (or more)? What happens if you wiggle the ones in the suspect area?

Could be a broken trace too.

c

 

[cruff]

Do you have a DMM?  You could check the traces for continuity, just use a light touch so you don't accidentally make a broken trace look good.

 

[Johnnya101]

I do. Right now I'm working on finishing up my other good keyboards, and maybe within the next few days I can start some testing. Someone else said that the capacitors might be on their way out. Haven't heard that before for keyboard caps.

 

[Johnnya101]

Ok. I am officially stumped.

Currently typing on the broken AEK II.

Someone was interested in buying the working one and maybe the broken one from me. I put them back together and tried them. Of course, the good one worked great. Then I tried the broken one... It worked.

The broken one usually works for about a minute, and then will randomly just have all of the lights light up OR turn off, and then I cant type anything. If I unplug it and plug it back in (Im using an ADB to USB adapter on my modern PC. By unplugging, I mean by the USB plug.) it works fine again, until it doesnt. Which is random. USUALLY, tapping around the top of the num pad area (Where the lights and IC is) messes it up. But, as soon as I unplug it and plug it back in, it works great. Am I looking at a bad trace? Bad IC? Transistor? If it was a broken trace, then why, as soon as power is cut and applied, does it magically work again?

??

 

[CC_333]

Well, maybe it's an intermittent trace, and tapping in that area confuses the controller IC, causing it to go to some sort of fail-safe mode, and cutting and reapplying power resets it?

c

 

[Johnnya101]

That sounds like the cause.

The guy who bought the first keyboard also wants the broken one. The fix will remain a mystery. Thanks for everyone's help.