hp42s locked up


I have an hp42s which had not been used for about 1 1/2 years. I've just put in new batteries to find it no longer performes the simplest arithmetic functions. I can put a number into the x register, move it up to y, and that's about it. I understand its obsolete, not covered by HP anymore, but does anyone know if it is repairable. Is ther something simple I can do to get it working again? Seems like 7 or 8 years ago is when I got it from hp for trading in an hp45 I had had for many years.





just to know: what other operations have you tried but simply entering numbers? What does it happen if you press:


Have you tried the 'master reset'? I do not know the keys by heart; just press together

[ON], [A] and [F]
. This might clear all memory.

After knowing what happens then, we can tell more about it.



A common problem with 42S machines is a bad keyboard. Try to see if any of the other keys do anything. I have seen a couple of units (and have one myself) where the rightmost column of keys is mostly defective. Some will give a response if you press hard... sometimes. Repairing a 42S keyboard is no fun at all. You have to open the machine (a real pain) then remove the cpu and keyboard (a real real pain) then get it all together again. The problem is the machine and keyboard are held together by melting posts (heat stakes) during manufacturing. These machines were not designed to be repaired. If you have access to an ultasonic cleaner you might give it a good buzzing... probably best to at least open the machine first. See Paul (?) Brogers article for details.

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