Sanyo ICC-82D : usable without internal battery ?

[Mark]

Hi, and thank you !
You're right, it's the most secure and straightforward method. I didn't choose it because I wouldn't be surprised if the machine can actually be safely AC-only powered :

The transformer / rectifier subsystem is identical to the one described in the ICC-0081 schematics diagram. Two secondary windings are used : one is the "main" supply, the other one is dedicated to battery charging. Noticeable difference : a 22-ohm resistor limits the charging current. Strangely it doesn't show up on the 0081 schematics !
At first I suspected it was blown, since I have no output. It is OK but the cable is internally damaged near the connector which plugs into the calculator.

What's interesting is that without any voltage fed to the battery (actually checked at its terminals), the calculator runs fine when powered only from the other transformer secondary. I'll reverse-engineer the mainboard's power supply section : there must be some electronic commutation system (diode ?) which should prevent any overvoltage risk if I keep the charging circuit unpowered.

More news soon :-)
Marc