HP 27s keyboard problem


I recently obtained an used HP 27s from eBay. Unfortunately, I discovered that the number 1 key does not always register. If I tap this key like I do with all the other keys, this particular key registers about 80% of the time. When it fails to register, I need to make a hard press to get the key to register and sometimes I get duplicate registrations of the key when I do this. I find this behavior rather strange. Can anyone explain why this key behaves like this and if there is a possible fix?

Edited: 6 Jan 2005, 1:48 a.m.


Such problems seem to be common on aging pioneer keyboards. While difficult, successful repairs of pioneer keyboards have been reported, see
this thread for example.


It really depends on what is wrong. You might have:

  1. Dirt in the key. Not bad, it should clean up.
  2. Something spilled in the keyboard. Okay, but tougher to clean since you don't know what it is.
  3. A just plain worn out key contact. Ugly. Major surgery, follow the previous link and good luck.

If it is just a dirty key, in the order of effectiveness:

  1. Ultrasonic cleaning of the entire unit which cleans inside the keyboard.
  2. Placing a few drops of isopropyl alcohol between the key and the surround and pressing the key a few times. Works many times for not-so-bad units.

Any cleaning should be done with batteries out and allowed to dry throughly before reinstalling. Leaving batteries in a wet Pioneer will result in keyboard destruction via electrolysis in about 24 hours.


Thanks to those who responded to my post.

I don't know whether it was my pressing of that key a few thousand times or the isopropyl alcohol or a combination of both but the key registration seems to have improved.

Incidently, I don't have access to a chemistry lab where ultrasonic cleaners are used. Where do you suggest I can get hold of one to use if I have a need for such equipment?


It's not something you would buy for a one-time cleaning. Units large enough to do the job are $200 and up.

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