HP Forum Archive 09

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HP41C Message #1 Posted by Ray Fuller on 2 Dec 2002, 2:47 p.m. Hi After some 10 years I came across my 41c calculator. I knew the rechargeable battery was dead so went and got 4 new N batteries. Cleaned the battery contacts and tried it and got no display. Looking for any suggestions to try or is it something that might not be fixable. Also found my HP45 and that worked like a charm after 15 or 20 years. Please let me know where to start? Ray Fuller

Re: HP41C Message #2 Posted by Bill Wiese on 2 Dec 2002, 2:58 p.m., in response to message #1 by Ray Fuller Ray... *Sometimes* HP41s (C/CV/CXs) don't always power up after a "big sleep", battery change after discharge, etc. Before we go on, I trust that the N cells are all good and are inserted properly? No corrosion on the 41C batt terminals in the compartment? Do a full reset (i.e., try for MEMORY CLEAR). Try this also WITHOUT the batteries installed. Short the terminals, let sit for awhile, rinse, lather and repeat... There IS a chance that over time the polymer & PCB connector "sandwich" between the two halves has lost contact, tension, etc. Lightly but firmly squeeze the calc front & back, along the system keys (ON/USER/PRGM/ALPHA) and down by the numeric area (centered on [5] key). Bill Wiese San Jose, CA

Re: HP41C Message #3 Posted by Vieira, Luiz C. (Brazil) on 2 Dec 2002, 7:49 p.m., in response to message #2 by Bill Wiese Hi; I've seen that the worst corrosion OR oxidation remainder is the one between the IO/BATT assembly and the mainboard. In many cases, opening the calculator and cleaning the contacts between these parts will allow it to work again. There is another "maneuver" one can try: shortening the electrolytic capacitors. They are easy to find in both fullnut and halfnut: check for the bigger components and shorten their terminals with any conductive metal. You can use paper clip previously folded so it will shorten the capacitors terminals. Go for the big one first, then to the smaller one. In most cases, the sleeper awakens. Anyway, try other alternatives before opening the calculator; avoid this as often. Cheers.

Re: HP41C Message #4 Posted by Ray Fuller on 2 Dec 2002, 7:51 p.m., in response to message #2 by Bill Wiese Tried draining memory and also measure voltage at Battery terminals. It was 6 volts of the proper polarity with a jumper across middle battery terminals. I am pretty much convinced that it is poor contact between the keyboard deck and main board. I looked at the article of Stefan Vorkoetter, who seemed to have a similar problem. He states just lift the circuit board out. My calculator has a hex nut? stud? where the screws were removed. It doesn't just lift out and I don't dare force it. The calculator did work alright 10 years ago so I wouldn't expect a faulty component. Anybody got any ideas

Re: HP41C Message #5 Posted by Ray Fuller on 3 Dec 2002, 10:20 a.m., in response to message #4 by Ray Fuller Got it working I think shorting the capacitors did the trick. Thanks Ray Fuller

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