Disassembling dusty HP27S


I bought a very dusty HP27S, where dust came inside and reduces the visibility of the display. In my opinion the one possibility to clean is to open the calculator, but I couldn’t find any way without applying brut force. So I gave up.

Is there an easy procedure for opening available.


This was the question sent 14/1/05.

Two tips came up. Once more many thanks therefor. For want of an ultrasonic cleaner I used compressed air that I blast in from all sides, where I could make a little gap between top and bottom side of the case. Many dust came out and also the display is clean now. But unfortunately the calculator does not display anything now. In my opinion the flexible contact sticks between display and board are misplaced. But how to get them in the right position. May be I'm fully wrong with my theory, as I don't know much about the inside of calculators.

In any case help is highly appreciated.


If you want to open it to attempt repair (at your own risk, of course), instructions can be found here and also discussed here.


The display zebras cannot be blown out of place.

Try discharging the backup capacitor first. Remove the batteries and touch a wire between the two terminals for a second or two. Reinsert batteries, you should be okay.


Thanks guys, there is nothing about good advice. The calculator is reanimated.

Say me well to the HP-community.


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