Posts: 4,027
Threads: 172
Joined: Aug 2005
Hi;
I guess it's an HP48S or SX; did I get it?
If so, chances are it's an aging process. I have an HP48SX and I bought it as soon as it was available (1990 - Serial # 3042A02xxx). It's LCD has a few small spots, and I believe it's an unreversible process. In my case, it seems a sort of a chemical reaction (oxidation, perhaps?) surrounding the right-shift annunciator. It's slowly advancing over the dot-matrix, but seems to be in a resting time... it's unchanged for about a month.
Yours seems to be a change in the reflected color (light). Seems to be harmless, I guess.
Sorry not helping that much. <:-(
Cheers.