My dad recently gave me the original Apple ii plus that he bought and I learned to program on. It wouldn't boot and after some troubleshooting, I found the highest range of RAM had a bad chip. I replaced the entire bank of 8 chips (as I saw was recommended on one of these forums) and it worked! I bought some new 5.25" floppies and was able to create some new disks using the Apple Disk Server (awesome resource!) The power suplly is working but I proactively ordered a capacitor replacement kit.
So everything is going great - my 17 year old even started writing programs on it because they love the challenge :)
And then the letter A stopped working :( I popped the key cap off and blew out the dust and I tried the hit-it-1000-times-trick but it's still not working.
I am an eletrcial engineer by training and learned to solder when I was 12. So I'm up for the task - I simply cannot find replacement switches.
Anyone no where I can source Apple ii plus key switches short of buying a spare apple ii plus? Or is there some other technique for repairing a switch I haven't found in my google searches yet? (I do have contact cleaner but I'm unclear where exactly to use it - do I need to remove the switch and take it apart?)
Thanks!
Warby
Can we assume you did that?
Yeah, ohm meter showed open circuit with and without keypress. Nearby working keys generally showed ~10 ohms or less when pressed.
You do not need to take it apart.
For at key switch you spray it down the stem of the key so it runs into the switch house.
Then massage the key a bit and let it sit a while (15-30 min).
Repeat if necessary.
Many times that can save a stubborn key switch.
The key is probably just dirty and not making contact. Here is how I clean stuck keys on Apple ][ and ][ Plus computers. It is a slow process, but I'm patient.
1) First I use some DeOxit on the bad key and work it a few hundred times. Spray the cleaner down the stem and let it soak a few minutes before working the key stem. Other contact cleaners are okay, but DeOxit's reputation as the best is true. That often works. Repeat a couple of times a day or two apart.
2) Next, I desolder the bad key and shake vigorously for 30 seconds. Check continuity with a meter. The last time I tried this with the full keyboard, before removing the key, I stuck a couple more keys...
3) Throw the bad switches (without the key cap) in a soapy water for a day or two, then put the container on top the clothes washer for a cycle or two on laundry day. The slight vibration really seems to finish up the stubborn ones. Check continuity with a meter when dry.
4) For those that still fail, I repeat the soak and vibrate with vinegar. This seems to fix 90% of the bad keys.
5) I don't take the keyswitch apart because I have never been able to get them back together successfully. I know some people replace broken stems etc. You may have better luck. I have had no issues with reassembling //e keys, but ][ Plus was a different story. Did I mention I'm not very mechanical...
6) Replace the keyswitch. You can post in the Wanted to Buy here on Applefritter and get responses or go to ebay. At ebay, you will likely pay more to buy the same part from the same people. There are several keyboards used in the early Apple ]['s and failed keyboards were often swapped so an early or late serial number computer might not have the original keyboard. While keyboards are intechangable, the keys really are not, if you get the wrong keyswitch, the angle and height might not match the other keys. Mike Willegal (who is often in these forums) has an excellent article here to help identify the correct one for you http://www.willegal.net/appleii/early-a2-keyboards.htm. Here is another good article on https://deskthority.net/wiki/Apple_II.
7) Here are some youtube videos I had bookmarked on keyboard repair that might be helpful.
https://www.youtube.com/watch?v=wVUWaodwNNI
https://www.youtube.com/watch?v=7_Nn238VQFY
https://www.youtube.com/watch?v=YzzwPg8hkbo
Thanks for all the great tips and resources. I will give those things a try and report back.
It wll be a while before I test - I just took everything apart to re-cap the powersupply.
I got the Deoxit today, and it worked perfectly! The letter A was 0% responsive for a couple weeks and is now 100% responsive.
I didn't even have to desolder the key switch. Just removed the cap, did a short burst at the base of the post. Pressed it a few dozen times. Another burst. A bunch more key presses. Then waited about 15 minutes to let it dry (the instructions recommended just a couple mintues.)
Thanks so much for this tips!
Warby