I/O Block: The corrosion trouble

Damaged battery contacts.

Damaged interface contacts.








I'm pretty sure most of you have seen the images on the left before... or even worse.

Corrosion coming from batteries (or alkalines) are by far the worst enemy of our beloved HP-41's.

The flex PCB that conforms the wiring between the Keyboard PCB - Battery terminals - Plug-in connectors, is the preferred "food" for that nasty blueish stuff that, in the end, will ruin HP-41 making an unsusable "plastic box" out of it.


Same I/O Block with new Flex PCB attached.




Now there is a suitable replacement for that badly damaged Flex PCB's.

A new glod platted flexible PCB with the same dimensions and layout of the original. Back coated with a Very High Bond (VHB) 3M adhesive layer that ensures a perfect shape fit.

If you're interested in refurbishing your corroded I/O Block, you more likely want to have a look at the last picture... ;-)

See the new Replacement procedure guide. (Ver.2)

NOTE: The Improvement "cooking" process. is a delicate process; please do not go this path unless you have an accurate temperature controlled oven.


The replacement Flex PCB: New life for your HP-41!... ;-)


This is the thing.

It will allow you to rebuild your I/O block in three steps:

1st. Remove the old damaged Flex PCB and any remaining plastic rivets. Make sure you got a flat plastic surface as it is essential for the correct bonding of the new PCB. A thin and sharp X-acto knife will help a lot here.

2nd. Bend the new PCB to conform the shape of the plastic base. You can use your old circuit as a guide. It is of the most importance to produce bendings as sharp as possible. Be confident, the new PBC won't break by over-bending... but be careful also, try to bend at the correct line in first instance as it is not recommended to bend-unbend repeatedly.

3.- Carefully and progressively peel off the protective back coating and apply good pressure for the adhesive to fix the PCB on its place.

Please mail me if you want to know more details about this replacement Flex PCB.