HP Forums

I want to share an approach for renewing the battery contacs of Woodstock calculators like HP-25, HP-29C.

Often they are in very bad corroded condition. Therefore I tried to replace them. The old contacts must be removed by drilling with a 2.5 mm drill. They are made of nickel plated solid brass.



I inserted two 2.5x6 mm "round head rivets" with 2.7x6 mm brass washers. After removing some solder resists from the board I could solder the washers to the copper traces leading to the battery.



The final prototype



I made the washers a little bit smaller with a Dremel tool, you need to use AA flat top batteries. Ideally would have been 2.7x5mm washers, but I didn't find them. Even better if they would be gold plated. I bought some gold electrolyte and perhaps will make a try.

Bernhard

Thank you!