damaged hp?


Hello to all!!

This morning i spilled coffee on my hp. i immediately turned it upside down to drain. i then went and got a wet paper towel and wiped the outside off. I thought that i should try to take the top cover off to clean under the keys but i was unable to do so. when i turned the calculator back on i got the great message asking if i wanted to try to recover the memory. when i hit the button it didn't do anything. the only button that seemed to work was the on button. i tried resetting the calculator using a paper clip under the rubber stopper on the back. when i turned it back on the buttons still didn't work. HELP!!!!!!


Hi, Seth;

you have which HP48? Or it's an HP49?

In any case, I read here that clear and neutral water is the only way. If you spilled coffe closer the the area between the display and the keyboard, it's exactly where the keyboard connects to the mainboard. Any substance that is "inserted" between both the keyboard "sheets" and the mainboard contact pads will cause problems.

As it is coffe, opening the calculator and removing the mainboard for a cleaning procedure is the most efficient way, but it is actualy the hardest. There are many procedures to open an HP48 and some of them are already described at www.hpcalc.org. I do not knwo exactly where in this site are these procedures available to download, but other contributors will help you better.

I have done it a couple of times and I succeed. In one of them the keyboard "sheet" had its trails "destroyed" by battery leakage and it was not responding to key presses anylonger. As the mainboard was fine, using a "donated" "sheet" recovered the calculator.

If you want to use water to solve the residual coffe, it's also possible and others may guide you as well. I did not try it so far, but I know it's possible and viable.

Wait for other suggestions, please.

Success! Oh, yes; and if you understand Klingon: Qapla'! (thanks, Ernie!)

Luiz (Brazil)


First remove the batteries.

Second, as a professional photographer, if we got a serious case of salt water, muddy water, etc. in a camera we would remove the batteries, then submerge it in distilled water, rinse and change the water a couple of times and keep it under distilled water until it reached the repair shop. The big mistake was to take it out of the water and let air get to it. The air would cause steel to rust and mud or salt to dry in the works.

In the case of the calculator there is not much in the way of steel to rust, so with a drastic case of coffeeitis I would consider soaking it in distilled water, changing the water a few times, then drying it as quickly as practical. Drain it and use gentle heat from a hair dryer or the like.

Obviously it would be better if you can open it, but opening has its own dangers.


In emergency cases I have used an ultrasonic cleaner loaded with distilled water (remove all the port covers, etc). Repeat three times (change the water each time). Shake out as much water as you can. Place the machine in a very low oven for around 48 hours.


Hi, David;

as always, your tips, suggestions and techniques are thoughtful. This is something I'd like to do, because I believe it's the best solution.

Thank you for sharing these gems.

Luiz (Brazil)


The oven scares me. I had a plastic slide rule that was warped. I got the idea of heating it just enough in the oven to straighten it. All the tick marks and lettering literally fell off!


I have cooked a lot of calculators without problem. My oven can be set to a fairly low temp (I'm not sure how low it is). Most electronics has max allowable storage temps of 50-70 degrees C. Remember that these machines were meant to be able to withstand being left in a closed car... which would probably make a good substitute for an oven... keep out of direct sun.


How about this idea. After you rinse two or three times in distilled water, toss a bunch of dry towels in a clothes drier. Heat the dry towels up (very hot). Then pull the towels out and toss your calc into the towel pile. Repeat every two hours or so (this avoids using an oven with a poor lower temperature control that might over heat and melt your calculator). The Towels will heat your calc and absorb the moisture. If you do have an oven that you can trust to keep the temp regulated between 110 and 130 degrees F it would be faster and better. But normal ovens may not be that reliable, Temperatures over 150 F will probably damage your calculator.


Thanks to all but my calculator started working again yesterday afternoon. You can tell it's a little sticky under the buttons but all in all it works. Thanks guys.


I left my HP42S on a warm windowsill for several hours after shaking it fairly violently edge on to get all the water out. But it seems to me that you could also tie it up in a plastic bag with a couple of those silica gel satchels that come with every electrical appliance you purchase nowdays. After all that is the purpose of them to remove any traces of moisture from the appliance.


I'm not sure that silica gel would do the trick quickly enough... the idea of heating is to raise the vapor pressure of the water... then the silica gel could absorb it. I suppose you could put the calc in a vacuum... that'd result in the water vaporizing.

Yes, that's a good option. Take your trusty shuttle to orbit, and throw the calc.... never mind.

I wonder if placing the calculator in the blower side of a vaccum cleaner would work? If the calculator were immersed in the flow, the entire unit would be at a lower pressure, driving out the water vapor, which would be then blown away...

When I clean calc parts, I use this method to dry the cases, boards, etc.... but I'm not sure it would work on a whole calculator.

Just some ideas.

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