Casio College fx-80 : which IC hides inside ?

[Mark]

Hi Jose,

I didn't know of that fx-81 ; it's a white fx-80 from which statistical functions and polar - rectangular conversions have been removed. The opened machine looks exactly the same as my fx-80 which was a gift from a colleague ; surprisingly it's not as easy to find in France. The 5 components you can see are the same, the ceramic capacitor is connected to the clock oscillator running approximately at 100 KHz.

When I got that calculator, the case was cracked because of the high constraints from the too strong battery contacts. I chose to replace the batteries with a CR2032 cell (socketed). I unmounted the PCB to replace the 2 wires that were deeply corroded by battery leak, then I discovered that the IC is almost completely hidden under the display.

My concern about not disassembling the display is that undoing the clips holding the LCD in place may weaken them once twisted back. I already had such a bad experience of a broken clip : the metal was corroded enough that it didn't survive a gentle handling.

Now you've got the whole story :-)

Regards,
Marc

EDIT : new episode ! Having looked once again at rskey.org, I was surprised to see that the HD36130 (supposedly reporting the same forensic result as the fx-80) is found in the fx-29. I pulled my fx-29 from my storage and a few seconds later got this result : 14.462524. I misinterpreted the "sorted by result" table. (have a look at it, you'll understand why)

Now we can tell that the NEC chips D1897G and D1898G are very likely the ones to be found in the fx-80 AND the fx-81 (or reversed). That's for the theory of course.....