CASIO fx-4000P scientific calculator from 1986

[Dave Britten]

(12-05-2015 03:25 PM)jebem Wrote:  This specimen had poor LCD contrast.
The issue was fixed after cleaning the battery holder connection pads on the PCA.

Thanks for the tip, I've got a Radio Shack version of the fx-4000P (EC-4020), and it had flickery contrast. Cleaning these two contact pads fixed it right up. I had been assuming it was an issue with the contrast pot. I think I've got at least one FC-200 that could use the same treatment.