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The Apple IIe is an Apple desktop computer released in January 1983. It was the successor to the Apple Plus and the predecessor to to the Apple llc.

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Keyboard typing random letters/numbers and repeats?

I’m working on an vintage apple iie, and I’ve encountered 1 snag that I cannot figure out. The keyboard works, yet no matter what keys are pressed, it only ever types k,y,x,1,3,:,/, etc. What do I need to fix in order to get it typing properly again?

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Sounds like the keyboard has shorted out (possible liquid damage). The only thing I know to do is replace it. This video may be of use to you:

https://www.youtube.com/watch?v=UhXmUHXh...

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I thought about that, but I examined it and found no damage of that sort. And the whole board gets perfect continuity.

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That thing is only 35 years old and it was quality built. I don't every remember repairing either a II, II+ IIe or Lisa keyboard that had not had a spill. The problem may be finding parts. I trashed all my pre Mac parts in 1998 as there were no calls for them. I'm searching for a 400k disk drive now for a Mac+ 1984 and not finding one.

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It could also be a bad rom considering it’s age. I’ll examine it farther for a short, but I’m not totally sure it’s that. It also refuses to communicate with the Disk interface card.

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I had this problem and fixed it. Here are some things to try:

  1. Find the large keyboard encoder chip at location D-14 on the motherboard. It will say “AY-5-3600-PRO” on its label. Pull the chip out of its socket and push it back in a couple times. This will scrape through any potential corrosion that developed on the pins.
  2. If that doesn’t make a difference, use a multimeter to check the two prongs on each keyboard switch. They should be nearly 0 ohms when the key is pressed, and “OL” or open, otherwise. If any of the switches are letting some current through when they shouldn’t, or not enough when they should, this can trip-up the keyboard encoder. If you do have bad key switches, you’ll need to have soldering skills to remove them to clean or replace them.
  3. If there’s still a problem, the next thing to try will also require soldering skills. Replace the disc capacitors C70 (47pf) and C71 (22nf) at location E-14, right under the chip.
  4. If that still doesn’t work, then the keyboard encoder chip is probably bad. You can replace it with parts: AY-5-3600-PRO or alternatively KR3600-PRO will work too.

When I had this problem, I replaced the keyboard encoder chip first and that didn’t solve the problem completely. For me it ended up being a combo of some of the key switches internally shorting out slightly, and bad C70 and C71 capacitors. Once I fixed those, the original keyboard encoder also worked just fine.

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Please, what are the capacitors voltage. Is 50v ok?

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Ed Dugan さん、ありがとうございました!
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