HP Forum Archive 13

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41CV turns off after 30 seconds Message #1 Posted by Matt Kernal (US) on 25 Aug 2003, 6:09 p.m. I picked up a good condition 41CV at a thrift store the other day (paid less than $1)! It has very slight indications of minor battery leakage, but no corrosion damage. I took the N-cell batteries out of another 41 (which works perfectly BTW), and inserted them into the "new" 41CV. Everything seemed to worked great on the new one, but it shut off after 30 seconds of no activity. Any thoughts/ideas about having it to stay on longer? I didn't think the shut-off time was programmable (I could be wrong, I don't have my manuals handy). Thanks, Matt

Re: 41CV turns off after 30 seconds Message #2 Posted by David Smith on 25 Aug 2003, 6:44 p.m., in response to message #1 by Matt Kernal (US) Open it up and clean the circuit board, back of the display, connections, and keyboard with 91%+ isopropyl alcohol. Keep the alcohol off of the display window. It will leave a white stain. If this does not work, there is a capacitor on the CPU card that controls the timeout system (actually the LCD module does the work). The HP41 service manual is on the HPMUSEUM CDROMS.

Re:42 repair -->alcohol damage to display lens Message #3 Posted by Katie on 25 Aug 2003, 7:31 p.m., in response to message #2 by David Smith If you do accidentally get isopropyl alcohol on the display window and it clouds it up, it can easily be removed using Novus Plastic Polish. Use their #2 to clean off light scratches and the #1 to polish with. #3 is too harsh for most circumstances. The best prices on this stuff seem to be from tanning supply companies (of all places!) like: http://www.tanforless.com/tansup.html

Re:42 repair -->alcohol damage to display lens Message #4 Posted by Grant Goodes on 26 Aug 2003, 10:46 a.m., in response to message #3 by Katie I concur that Novus is easily one of the best plastic polishes out there, and that #2 is the most useful. It has a very gentle abrasive, as well as cleaning compounds, and will remove ground-in dirt, restoring plastics to their original luster and colour. I use it for pinball restoration, and have sucessfully used it on the plastic cases of HP instruments that had yellowing due to age/dirt and possibly tobacco. You can apparently find it in most Harley dealerships, and some box-stores. Us pinball types buy it in large jugs from pinball parts dealers. grant..

Re: 41CV turns off after 30 seconds Message #5 Posted by Daniel Diggelmann on 25 Aug 2003, 6:45 p.m., in response to message #1 by Matt Kernal (US) Hi Matt, I have experience the same problem on a fullnut HP-41CV. I actually was a bad contact between the CPU board and mainboard. After cleaning the contact with ISOPROPYL Alcohol the calculator switched off after the usual ~10 minutes. The reason for this is that the shut off timer is part of the display assembly and not of the CPU assembly. Good luck Daniel

Thanks for the advice... I'll try it. (NT) Message #6 Posted by Matt Kernal (US) on 27 Aug 2003, 6:27 p.m., in response to message #1 by Matt Kernal (US)

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