HP Forum Archive 06

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42s not holding memory Message #1 Posted by al on 4 Aug 2001, 12:47 p.m. My 42s was soaked under water about 4 months back. i put it away and remembered it about a week ago. i put in some new batteries and then i programmed it. It worked fine until a couple days when it lost all memory and seemed to be going haywire. i put it down for a day and shorted the terminals. it started to work again, except, any time i remove the batteries it makes a high pitched noise and a line comes up on the screen for a split second. on re-inserting the batteries it shows memory clear. It's not holding the memory even for 5 seconds. Any advice?? I also have another 42s that is dead. I am sure i would be able to salvage something from one to place in the next. oh and most importantly, it never fails the self test.

Re: 42s not holding memory Message #2 Posted by Tony Duell on 4 Aug 2001, 2:10 p.m., in response to message #1 by al My guess is that you've got salts, etc from the water causing leakage between the PCB tracks in the HP42S. Since the 42S is hard to open without damaging the case, I would start by taking out the batteries and washing the entire machine (assembled) in distilled water. Then wash it in propan-2-ol (isopropyl alcohol). Let it dry (at least overnight), and try it again. If that doesn't help, you'll need to open the case. I always remove the metal overlay from the front first, since that reduces the damage to the plastic parts, and then drill out the tops of the heat-staked studs holding it together using a 3mm (1/8") twist drill held in the fingers or a pin chuck (not a hand or power drill). Once you're inside, try really cleaning the PCB with distilled water followed by propan-2-ol, particularly between the pins of the components. Since the machine works, it's unlikely there's anything wrong with the chips, and anyway they're pretty well sealed so water won't damage them at all.

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