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How to fix an old HP41cx
05-19-2020, 11:55 PM
Post: #1
How to fix an old HP41cx
Hi all,

I got an old HP41CX that is working partially. It’s difficult to power on, it powers on randomly pressing the on button. Keyboards works partially and also there randomly. LCD sometimes changes brightness an suddenly disappear. I think the calculator has been already opened and probably need a full verification, cleaning and tightening of all screws. But It m afraid to broke something in such a fragile calculator. Is there any tutorial/suggestions I can follow to make this work well done ?

Thanks

Bruno
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05-20-2020, 06:21 PM
Post: #2
RE: How to fix an old HP41cx
Try my post for places.

https://www.hpmuseum.org/forum/thread-14904.html

A lot of people pitched in and commented. They were awesome!

BLUF: The Calculator Store has parts and repair "How-To's". Not on everything but most of what may be your problems.
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05-21-2020, 03:42 PM
Post: #3
RE: How to fix an old HP41cx
The 41 depends upon the lower two screws to clamp the top and bottom of the calculator together. But they play more than a structural role. That clamping force also establishes good electrical connection between the top and bottom via the "zebra connector". Google "HP41 zebra" without the quotes and you'll get a lot of hits including pictures to show you what I mean. Anyhow, if the screw posts (especially the lower ones, as the zebra connector sits right around these) are cracked or broken off, you won't be able to have sufficient clamping force and all sorts of gremlins ensue. The vast majority of the time, when a 41 is acting really flaky, it's because of that zebra connector and the main ultimate cause is broken/cracked screw posts which need to be repaired or replaced.

Let us know what you find.
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