41CV from craigslist

I have my first opportunity for some vintage calculator restoration...

I saw a 41CV advertised on Craigslist for $50. When I went to get it I saw the contacts were corroded. I removed the corrosion I could but it would not power up with new batteries. I bought it for $20, thinking maybe I could get it working somehow.

The foil is corroded back to the connector on one side but the contacts to the main board themselves look good.

what is the best way to get this fixed? Find another non-working donor which has no corrosion and swap out the back? Solder a wire from the connector to the battery compartment? Or is there a way to repair the foil on this one?

I know there is some info in other threads, but I find it terribly difficult to search the forum.

I appreciate any advice on this...


I know there is some info in other threads, but I find it terribly difficult to search the forum.

Easily done if you use Google (not an advertising!). Using site:www.hpmuseum.org HP-41 fixing battery contacts as the search key, for instance, returns 1000+ hits. Stefan Vorkoetter's great article appears to be what you are looking for:

Repairing an HP-41CX

Good luck!


Thank you.

Also for showing me how to limit a search to a specific site. Didn't know that...

I've always tried using the archive search with mixed results.

Edited: 12 June 2012, 11:54 p.m.


Hi David,

You may want to have a look at my web page regarding the I/O Flex PCB here..

If you think this can be useful, please contact me privately to "clonix41(at)gmail(dot)com".




Having used Diego's flex I/o to restore three battery/module blocks I can certainly recommend them.

Cheers Geoff

Edited: 13 June 2012, 12:03 a.m.




Hi Geoff, Kerem,

Thanks for your support... :-)

BTW Geoff, I'm (as many others) waiting for your book; this is not intended to hurry you up whatsoever... (I know quality needs time :-) just wanted to know if there is a procedure to join the waiting list which I may not be aware of.

All the best from Caribbean Sea.



Email me and I add your name to the list. Your name is actually on the list due to your 41cx CLONIX and flex I/o help.

Cheers, Geoff

Looking at compleetion for HPCC 2012

Edited: 13 June 2012, 12:49 a.m.


I can only confirm that the contacts foil purchased from Diego are the best for this kind of restoring. I've restored ten or more block contact with complete success.

Be confident



If the traces are okay at the keyboard side connection, you can cap the damaged connection points with short lengths of 1/8" brass u-channel (available in most hobby shops). If the damage to the ends is worse than the one shown, and you cannot solder the cap on at the edges of the foil as shown, you will have to scrap away the coating, down to the copper and then solder both top and bottom areas. The top area to solder is shown circled in red. Duplicate on the bottom. The bottom connection connects the circuit, the top just helps to hold it in place.


David, what is the "Craiglist"?
...apologize for my ignorance, but, I don't know what do you mean



.....what is the "Craiglist"?

It's a very popular collection of US local "for sale" websites. Sort of like classified ads in a local paper - deals are typically person-to-person for items but ads also cover things like apartments for rent, etc.

Edited: 13 June 2012, 9:42 p.m.


Thanks, Randy.

I don't have a good way to post a photo right now, but the corrosion runs up right next to the contact with the main board. I doubt there is more than 1/32" good foil just before the contact point with the board. It is a real mess.

I went ahead and ordered a new part from Diego. Hopefully that will come in soon and I'll be able to replace the whole piece.

Thanks for all of the input!



It's actually worldwide.

here is Craigslist in Rome.

Edited: 13 June 2012, 11:16 p.m.


Bob, Les, Thank-you

From a place you can surf to the other towns I see...interesting


Edited: 14 June 2012, 3:19 a.m.

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