HP Forum Archive 16

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Half Defective HP 41C Message #1 Posted by jbssm on 30 Mar 2006, 7:42 a.m. Hi all again, I have an hp 41CV that is behaving very strangely. The left half of the digits in the LCD work fine and have good contrast, the right half of the digits almost doesn't show up. :-S To me, this is a very strange behaviour, I would expect that all the digits or none worked. Also, everytime I press a key, the calculator emits an high pitched beep, is this normal behaviour? I mean, I know it's not completely normal, but is there any option in the calculator to do this? And how do I turn it off? If you have any idea about the problem and/or how to fix it, then I would be glad to hear you. Best regards to all the contributors to the forum, jbssm

Re: Half Defective HP 41C Message #2 Posted by Eric Smith on 30 Mar 2006, 11:45 p.m., in response to message #1 by jbssm If it's a "fullnut" 41CV, there are two separate display driver chips for the left and right halves of the display. Both chips must have working logic, or the display updates wouldn't work correctly for either half. But possibly the voltage divider that sets the levels for the right half has broken. The beep might be "buzz mode" if you happen to have revision HFF ROMs, which are uncommon. Buzz mode is more commonly seen in the 41CX. If that is the problem, a full reset (MEMORY LOST) should fix it. Otherwise I'm not sure what could explain it.

Re: Half Defective HP 41C Message #3 Posted by David Smith on 31 Mar 2006, 11:51 a.m., in response to message #1 by jbssm Take it apart and clean all the contacts internal (eventhose under the CPU) and back of the display with 91%+ isopropyl alcohol (keep it off the display window). Using a dental probe, gently pry on all the little fingers connecting the display to the keyboard. Resolder any that pop loose.

Re: Half Defective HP 41C Message #4 Posted by jbssm on 2 Apr 2006, 6:42 p.m., in response to message #1 by jbssm Hello, I managed to get rid of the beep, but the screen still doesn't work. I tried to clean the contacts, I also checked for broken contacts in the LCD, but they are all fine, finally I tried and putted the logic board of another unit in this place ... and surprise, the screen was defective still, so it's not fault of the controller chips. I really never saw anything this strange.

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