HP Forum Archive 18

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41CV Math Pack Power Problems Message #1 Posted by Peter Woysch on 11 Sept 2008, 7:54 a.m. Calculator can not be switched on after 10 minutes when the math-pack I is installed (no memory modules installed!). Only after removing the battery pack and reinstalling it several times it could be turned on again. Does anyone know this strange behavior? Other than that the calculator works fine also with the math-pack. Thanks, Peter

Re: 41CV Math Pack Power Problems Message #2 Posted by Dan Grelinger on 12 Sept 2008, 11:19 a.m., in response to message #1 by Peter Woysch Peter, I am going to take a guess, but first I have a question. Do you mean that it won't turn on after the auto off function has executed? Or that if you turn it off and turn it on within 10 minutes, it works, but if you leave it off fore more than 10 minutes, that it won't come on? The HP-41 executes polling points in each modules rom space when you shut it off. It is conceivable that the Math pack is damaged at that polling point, and locks up when it is polled. Dan

Re: 41CV Math Pack Power Problems Message #3 Posted by Peter Woysch on 14 Sept 2008, 1:21 p.m., in response to message #2 by Dan Grelinger Dan, Thanks a lot for your explanation. It's not after the auto off function. It happens when i turn it off and turn it back on within 10 minutes. Peter

Re: 41CV Math Pack Power Problems Message #4 Posted by Dan Grelinger on 16 Sept 2008, 11:46 a.m., in response to message #3 by Peter Woysch That is strange behavior, that if you wait more than 10 minutes after turning if off, it is able to turn back on again. About the only thing I can suggest is trying new batteries. This type of problem may be related to an interaction with the batteries and the small extra power requirements for the module. A bit of a stretch, but if the batteries are marginal, the extra time in an off state may allow enough voltage recovery to allow a turnon. If the module is not there, a somewhat smaller amount of power is required, perhaps letting the HP-41 turn on. One would expect the BAT annunciator to be turning on, though. Another guess might be that the math pac has a marginal thermal problem, i.e. when it has been used (and theoretically slightly warmer due to power dissapated from use) it has a failure that locks up the HP-41 when it is polled at turn on. This will prevent it from essentially turning on. If it has not been on for awhile, it cools down, and function is restored. You may try putting it in the fridge for awhile, turning it on, then off, then back on again. If it starts off cold, it would take awhile to heat back up, and you could rule in or out a circuit thermal issue. Dan

Re: 41CV Math Pack Power Problems Message #5 Posted by Palmer O. Hanson, Jr. on 14 Sept 2008, 11:13 p.m., in response to message #1 by Peter Woysch I couldn't help wondering so I put my Math Pak I in my HP-41CV and didn't see your problem.

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