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41CV turns off after 30 seconds - Printable Version

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41CV turns off after 30 seconds - Matt Kernal - 08-25-2003

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).


Re: 41CV turns off after 30 seconds - David Smith - 08-25-2003

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: 41CV turns off after 30 seconds - Daniel Diggelmann - 08-25-2003

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

Re:42 repair -->alcohol damage to display lens - Katie - 08-25-2003

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 - Grant Goodes - 08-26-2003

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.


Thanks for the advice... I'll try it. (NT) - Matt Kernal - 08-27-2003