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HP 41CV Interchangeable Main Board

PostPosted: Mon May 23, 2022 6:25 pm
by vervalin
I have an older HP 41CV (SN: 2123S11164) that has the main board from circa 1981 (it does NOT have any piggy backed chips). But nothing I do can make it come to life. I have done everything to try to make it work with no success. It worked for awhile and then one day I pressed the PRGM key and got a garbage display. From that moment it has degraded to the point that now the screen just remains totally blank. So, really my question is:

Are ALL the HP 41CV main processor boards interchangeable?

It seems like there were many, many versions of these processor boards that HP went through and I just want to know if I can pop in any old HP 41CV processor board and see if it will work.

Thanks!! Paul

Re: HP 41CV Interchangeable Main Board

PostPosted: Tue May 24, 2022 11:17 am
by BillBee
To the best of my knowledge the CV/C boards can be swapped with a few exceptions - Tall keys IIRC - display driver (?).

I've swapped boards quite a few times and it usually comes down to the zebra, ribbon, posts or case backs. Or a pleasant combination of them. Looking around the case seam if there is separation then that would be a clue. display end - case back. Label end - posts.

It can drive one nuts so I hope for the best for you.


Re: HP 41CV Interchangeable Main Board

PostPosted: Tue May 24, 2022 1:04 pm
by vervalin
Thanks Bill, This is exactly what I needed to know. I have owned and actively used HP 41s since around 1981 and have even made processor board changes like increasing the clock speed on my first HP 41CV. I have just never had to swap the main board. All of the things you have mentioned are right on target. I'm pretty sure I've checked all that stuff but I will make another pass just to be sure. The "garbage" display seems to me to indicate that a chip has gone bad on the board and then ultimately no screen at all. Anyway, thanks again for the reply, knowing the C/CVs are almost always interchangeable with few exceptions is a great piece of information to have. Regards, Paul

Re: HP 41CV Interchangeable Main Board

PostPosted: Tue May 24, 2022 5:01 pm
by BillBee
Glad I could help Paul.

The boards are pretty tough so I hope its just a connection issue.

Good luck and post a follow-up.

HP41 recovery success stories are great.