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I have opened an HP-25 for cleaning. Some keys donĀ“t work properly. How can I dissasemble the keyboard?

Thanks in advance

Jon

Don't dissambled it; it would be hard to get it work again!

You could clean it in a ultrasonic water base bath

Or if you don't have acess to this, use distillated water bath for "some time" and remove water with air spray of air from a compressor

Sometime i use a spray call "contact dexoidizer", it remove "rust" on the contact. You can find this at a TV repair shop.

Pay attention solvent cleaner, it can dissolve the plastic of the keys or the case itself! make a good test on the plastic before using solvent.

If you are lucky enough to have a keyboard with holes in the PC board for each key, this solution works every time:

http://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/archv010.cgi?read=26576

If you only have one or two bad keys on a keyboard without the holes under each key (usually these were only used on the 29C and 25C) then you can drill an acess hole under the offending keys with a hand drill. You need to be careful not to drill through the circuit etches though. They are easily visible through the circuit board material except on a very few that were made of an opaque black material.

I suppose you could drill keyboards with lots of bad keys, but your chances of messing something up go up pretty quickly. I have a 25C keyboard with about half the keys bad. My ultrasonic cleaner is on the fritz, so I tried soaking it in vinegar and rinsing very well. It worked fine until the next day when everything dried out fully.

I had a 25 keyboard (the one with a hole for every key) with very bad blue battery leakage all over it and I successfully cleaned it with diluted distilled vinegar. I don't have an ultrasonic cleaner, I use about half and half vinegar and water to clean battery leakage from everything. Sometimes I use hot tap water, that seems to speed things up especially thick deposits like on the battery packs themselves. Afterwards I rinse in plenty of tap water then in several changes of distilled water.

Ooooh, don't 'ya just love them crunchy feeling keys with the green and white poweders in them...