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Full Version: HP 42 S flaking out
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Recently my 42S started “flaking out”. 1) The self test says okay but periodically instead of going to sleep it starts beeping steadily and then it resets the machine 2)after a delay in keystrokes I think that the decimal point or some series of key strokes with the decimal point also imitates a machine reset. Any ideas?

Perhaps some cleaning of contacts would work if I could open it

Are the batteries fresh? Are you able to check the voltage of the 3 battery stack during operation? Anything below 3.8 volts and you will have trouble, maybe sooner. I have found the battery annunciator to not be a reliable indicator of battery condition.

A liquid spill in the keyboard may cause this behavior as well. Coffee, cola and others would certainly make a mess of things.

The batteries went dead, and I didn't replace them even close to right away. It was probably 6 months later that I decided to replace the batteries. Now, after replacing the batteries, I turn it on and get all the pixels in the display are 'on'. Any buttons I press, results in a beep. I've tried the self test - beep. I've tried the reset - beep.

Is it a lost cause?


The beep means at least the processor is running but perhaps the ROM fails checksum?

Anybody know for sure?

Could it be a bad battery? I would check them if you can.


have you already tried to briefly (a lot briefly) shorten the batteries' terminals? Get a little piece of conductive metal, preferably a wire OR a thin paper clip. Carefully remove the batteries' cap. WITH THE BATTERIES INSIDE THEIR COMPARTMENT, briefly (a lot briefly) shorten the batteries' terminals. Keeping the batteries there will NOT ALLOW voltage to go upper than the 4.5 Volts. Place the cap back.

Whatever happens, let us know.