HP48S strange behavior

[Daniel Sole]

Thank you very much, Mark. It didn't work but that was a good try indeed.
I'll look for Han's instruction and carefully follow it. I'll keep you posted upon fail or success.
Tks & Bst Rgds!

Daniel

(06-26-2019 02:31 PM)mfleming Wrote:  

(06-26-2019 01:41 PM)Daniel Sole Wrote:  I think there must be some "hardware" issue. But it's quite a weird misbehavior. From an electronic point of view, I can only guess some kind of short inside between circuit tracks.
Maybe I will dare to try to open the calculator and take a look inside. I've got a technical background and this doesn't scare me at all.

The most common failure mode for old 48 series calculators is a loss of connectivity between the keyboard ribbon connector and the cpu board. The failure usually manifests itself as a loss of a row or column of keys. Try pressing down on the center of the calculator just below the screen. If the weird behavior goes away, you have a connector problem.

The fix is fairly easy though opening the case is not. There are instructions (with pictures) posted in the old articles forum and in hpcalc.org directories. I followed member Han's detailed directions with success. With a little care you can have your old calc operating again.

~Mark