Hello,
I am currently refurbishing an Apple IIe I recently purchased and the keyboard is giving me quite a bit of trouble. It's an Alps keyboard, the one with the tall white stems on the keyswitches. One switch was busted, which I replaced and now works correctly, however there are about 6 keys that strike repeatedly on powering on the computer, like space and a few letters and numbers. I tested this broken keyboard on a working Apple IIe and the same problem happens there (plus tested a known working keyboard on the broken computer, which worked successfully), so I don't think it's a capacitor or the keyboard ROM.
So far I've cleaned all the switches with Simple Green, 99% alcohol, and Deoxit, done continuity checks on all the switches which are all working fine as far as I can tell. I looked over the traces with a magnifying glass and don't see anything unusual there, the solder joints look fine for the most part, but they are pretty old so its hard to tell if there are any cold solder joints. I haven't actually disassembled an entire keyboard before, but I'm not sure what else to check at this point. Replacing the switches is about $10 each on Ebay, but for that price I might as well just get a new (to me) keyboard altogether. Does anyone have any ideas on what else I can check before I throw in the towel? I'm somewhat new to doing this level of repair on these machines, so it might be something simple I'm overlooking. I did notice that someone had replaced the CPU with a 6502 instead of a 65C02, so I'm not sure what other shenanigans previous owners might have done. I'll upload a motherboard pic just for reference just in case something goofy is going on there, but the keyboard did cause issues on another computer so I doubt it.
Thanks!
FantasticDan wrote:
Which keys exactly? (That is important in order to determine if they are all on the same row or column of the matrix.)
Also what do you mean by "strike repeatedly"? Do you get 2-3 characters on the screen when you press them once, do they continue printing forever until you press a different key, or do they produce keystrokes without even being pressed at all?
It's the space bar immediately upon turning on, then it seems to repeat certain keys after you try to type something. I'm baby watching at the moment I'll have to reply with specific info tomorrow. I want to say I did check the traces to see if there anything in common with them but there didn't seem to be.
Those other key switches could be sticky and need to be cleaned and/or replaced also. Have you tried Deoxit on them?
Also, I have had some replacement key stems for //e keyboards 3D printed so I don't need to buy replacement switches or use up the stock I have from a couple donor keyboards. I can probably find the .stl files for that around here somewhere.
OK, this zip has a bunch of 3d files on it... the one for long //e key switch stems is: IIe_keyswitch_post.stl
Ok I did some additional testing, and tried to be as thorough as I could. What's going on is, the spacebar repeatedly strikes when the machine is powered on and don't touch any keys. I boot into something, like a diagnostics program, and it appears that whatever key I press gets repeatedly striked. I tested Esc, Enter, all the arrow keys, A, B, which are all on different traces. It doesn't appear to be a particular key, there's something going on with the keyboard itself as it does the same thing on two separate machines. The keyboard has been thoroughly cleaned and Deoxit'ed, and the keys all appear to function correctly when tested via a continuity tester with the keyboard unplugged. My guess is there's another component on the keyboard that's fried, but it doesn't look like it comes apart easily so I can't really see what's going on. I'll try and look up a schematic to see if there is anything of interest, but when glancing in from the side it only looks like a few resistors.
I found another thread where someone sounded like they had a similar issue with keypresses repeating on an Alps keyboard, and it looks like they had to disassemble each key and clean/tweak every key by hand. I found a schematic and both resistors check out, so I think I'm just going to quit while I'm ahead and buy another keyboard with a different switch style. I don't like the stems on these Alps switches as they are really delicate, and it looks like I need to replace at least 1 or 2 more keys anyway. I did swap the cable just in case, but it's still doing the same thing with both cables.
Thanks for the replies, I hate giving up like this but I think the risk of removing and cleaning each switch plus the time investment isn't worth it. At least I can reuse the grain of wheat light, which still works :)
Does it get repeatedly stroked just a few times and then stop by itself, or does it continue striking until you press another key, after which the new key starts striking continuously?
The latter effect happens if you hold down a random key on an Apple IIe without any keyboard issues. Therefore one possible cause is one of the keys being shorted pressed. I would suspect the Space key, as it is the most used and abused, but it could be any of the keys, except for the ones that do not produce symbols by themselves, like Caps, Shift, Ctrl, Reset and the Apple keys.
In this particular situation you can find exactly which keys is shorted down by pressing each key one at a time. The culprit key will appear not to work, as pressing it will not change the last repeating symbol.
Oh really? Hmmm that would explain why the switches seem to work via continuity tests. I'll do some more investigation with this in mind and post results of what I find. Someone bought the keyboard I was watching anyway, and I really would like to fix it if it's possible to do so. Thanks!
Ok I resoldered all the joints and tested each key with the computer on. A total of 6 keys don't work (space not being one of them). They're kind of all over the place so it doesn't seem like something whacked the keyboard. One key I knew about as it has a wiggly stem, but the rest feel fine when pressed. I don't think it's related to anything with the traces, as I would expect other switches on the same traces to experience issues. Just for reference, the 6 keys that don't work are: + R D H , →
The going price for these switches seems to be around $10 and replacement keyboards are usually around $75, so I still might be better off just replacing it especially as there's no guarantee replacing them will fix the issue. Is it possible to do repairs to the innards on these switches? The one switch I did replace I had a hard time removing, and consequently fell apart upon removal, so if there's a special tool or tecnique to removing them intact I'm curious as to how it can be done more easily. I can try Deoxit again to see if that works too, but if you or anyone else has any suggestions I'm all for it.
Thanks!
It is possible to open them up if they are the SMK type key switches. There are little tabs on the side you can pry apart. You can get 3D printed stems to replace broken ones. But it sound like yours are maybe just dirty/corroded inside. Or possibly worn out. I have a couple "donor" keyboards so I don't have to buy key switches, plus I have replacement stems so I can re-use even broken ones. They aren't that hard to get out. I use solder wick (copper braid) and just remove the solder and then they pop out pretty easy. If you are breaking them you are probably either using too much heat or you're prying too hard trying to force it out and there is still solder holding it in place.
Having a spare keyboard is a good thing so it isn't a completely bad idea to just buy another one and keep this one for spare parts.
After removing the key caps and spraying Deoxit on both side of the steam should fix most of them, but sometimes after long periods in storage you might have to do it again. Also make sure to exercise them extensively as soon as you spray it and apply a bit of side pressure in all directions as well.
Ok I finally got the replacement switch and replaced the most egregious one, and it resolved the repeating key issue. I still have a few more that don't work, but at least the keyboard seems salvageable now. I'll see if I can't get the other problem switches out and see if I can get them to work once they're out of the keyboard.
thanks!
A very common problem on IIe key switches.
Taking them apart and cleaning the contacts mechanically is usually the only way to truly fix them, but often times those contacts are quite corroded, dirty, or fouled in some other way.
Plus they're extremely delicate, and I've ended up having to trash the key switch I was working on because I damaged it beyond repair by repeatedly assembling and disassembling it.
Keep trying on those 6 key switches.
If you get nowhere, contact Steven Buggie - he's the key switch guru. Probably thru facebook. He keeps a stock of all sorts of spares.
It is absolutely possible to repair the switches. Desolder them, prise them open carefully. I take 2 very small screwdrivers and use them on each side to hold the locking tabs out, then slide the switch apart.
Clean the metal tab well with alcohol. NEXT, and MOST IMPORTANT part that no one mentions:
You must put a little more bend on the "fork". I put additonal bend on the fork at the crease just below where it splits , enough so it's sliding against the shaft.
Slide it back together and test it with a multimeter.
Ive repaired at lest 30 ALPS switches on II+ and IIE and only ever could not repair just 1 of them!!
I buy my switches from either Stephen Buggie or AppleIIonlinestore. I keep 5 spares under the keyboard of each machine for the future. I know they are getting brittle and one day they will snap when I take them apart. So far I never had to redo any - but using the machine regularly tends to keep them working.