HP Forum Archive 08

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41cv Message #1 Posted by b.tokarczyk on 3 Apr 2002, 8:18 p.m. I have a 41cv that reads 'memory loss' at battery insertion and will not respond to any keys, even power toggle. I've gone through Mier-Jedrzejowicz's brief recommendations. Is there any advanced options to get this operational? Regards, Bryan

Re: 41cv Message #2 Posted by Vieira, Luiz C. (Brazil) on 4 Apr 2002, 5:59 a.m., in response to message #1 by b.tokarczyk Hi; is your HP41CV the halfnut OR an earlier coconut (fullnut)? The basic difference is the motherboard, that exists only in the fullnut. If you're lucky having a fullnut, there is a possibility that you can get it repaired. In fact, I had one HP41C that happend to be exactly with this behaviour and I could get it working. Depending on what kind of board you have, you'll find one of both: - six 8 pin, DIP, memory IC's lined up at the right side of the board OR - three pairs of IC's, stacked built, in the upper top of the board In both cases, five of them are ILExxx series and one is an ILAyyy. This ILAyyy is the memory chip that holds system registers (ALPHA, X-Y-Z-T-L stack registers, among others). When this fella is not working, MEMORY LOST is shown and the calculator does not work. In my case, I could swing the calulator slightly and see the brief, tiny LCD's blinking (about 1 sec. delay) meaning the system was trying to restart. After removing the IC and replacing it (from another HP41), everything worked fine. Well, that's my story. I am almost sure that some other, easier to handle situation may happen in your case. Success.

41cv Message #3 Posted by b.tokarczyk on 7 Apr 2002, 5:13 p.m., in response to message #2 by Vieira, Luiz C. (Brazil) Luiz, Thanks for the info -- I'll check on the type and get back. The reversal of the batteries actually allowed me to turn the unit on with toggle, but then it displayed the same error and stayed without response to keys. Regards, Bryan

Re: 41cv Message #4 Posted by b.tokarczyk on 9 Apr 2002, 2:23 a.m., in response to message #2 by Vieira, Luiz C. (Brazil) Luiz, Thanks again for the response. The cv is a fullnut version. Again, my only success at a response is the momentary reverse polarity of the n-cells. I am trying a couple of various ways to get the display to at least respond to the keys/toggles -- unsuccessful so far. Any ideas would be much appreciated. Regards, Bryan

Re: 41cv Message #5 Posted by Vieira, Luiz C. (Brazil) on 9 Apr 2002, 7:40 a.m., in response to message #4 by b.tokarczyk Hello, Tokarczyk. There is a procedure I tried some times. It will probably be taken as risky by some contributors in here, and I agree it is risky. But I have done it more than a couple of times with successful results. You will find two capacitors built in the mainboard (the bigger ones). Allow the mainboard to rest outside the calculator's box for a couple of hours and shorten these capacitors' terminals (use a piece of flexible, thin wire). Both will retain battery’s charge and keep calculator's status for some time. Shortening them will 'reset' power supply and erase all memory contents. After that (make sure no residual charge is left in the capacitors with a voltmeter), find some conductive foam and allow the mainboard to rest over it, making sure all IC's terminals touch the foam. Let it there for a couple of minutes. Also, check for corrosion and dust in both BATT/IO assy and the zebra connectors between the mainboard and the keyboard/display board. Sometimes a single cleanup procedure will be enough. If you find oxide residuum, some metal polishing solution will help removing. I guess these procedures will eliminate external causes. If none of them get to successful operation, any of both the mainboard or the display assy is bad. The best shot, in this case, is having another calculator, so you can switch parts with each other and try to replace components. If there is something else I remember, I'm posting soon. Also, if there is something else you need, let us know. I believe other contributors will try to help, too. (there are great gurus in here, it's just a matter of time for them to read this) Hope you have success.

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