HP-41CV - problems


I received my recent acquisition - one old HP-41CV - but, connecting the batteries it didn't work at all.
I've checked the batteries contacts and could see problems on them. I fixed that. Tryed again - nothing. So, I get the back off and wired to the main circuit board an external 6V batteries.
When I insert the last battery, the display gets on with the message MEMORY LOST, or only LOST, or some symbols and the keyboard completely locked.
Is this calculator dead?
Please , HEEEEEEELLLLP!!!!!!


I have been using this calculator for 20 years and I have never had a problem.

When I turned it on this morning, the decimal has been replaced with a comma. I believe that it is in the Euorpean Mode. However, I don't know how to change it back to the decimal Decimal Mode.

Can anyone help?

Everything seems to be working properly, except my decimal has been replaced by this frustrating comma.


Please take a look at the user flags...because this is really RTFM.

SF 28 does the job.


Try with pressing and holding the ENTER key, then press and release the ON key, then release the ENTER key.
This is a reset (also RTFM;-)


I'll try the ENTER-ON-ENTER.
Thanks, Raymond!


Hi, Artur; (tudo certo?)

Have you checked if yours is a fullnut or a halfnut? Look at the image below:

Raymond's comments are very important. A simple reset may solve the problem. What worries me is the already exisiting [MEMORY LOST] message and the fact it is broken and shows unusual characters.

If your 41CV is a fullnut (earlier, "original" HP41 display), chances are you have a common bad contact between the small mainboard and the keyboard contacts. In most cases, a simple cleanning procedure is enough.

Tell us (ou me manda um e-mail) if you need extra advice.


Luiz (Brazil)


This one is the fullnut (without the rounded corners) and the CPU board is not model with NO transistors.


(Luiz, I've sent you an email)


Lift the CPU board off the posts, gently remove the zebra strip connectors. Clean everything with 91% isopropyl alcohol. Reassemble. Pray to your favorite diety. Turn on. Hopefully enjoy.

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