Needing help powering up a Sanyo ICC-801D

[sislasl]

(05-07-2021 08:21 AM)Nigel (UK) Wrote:  Here's a link to the sale of this model of calculator on an auction site: Sanyo ICC-801D.

In the seventh picture you can see an image of the mains adapter. Here's a snip:

You can see that the power supply supplies two voltages, 6.6V and 7.3V. My guess is that the 6.6V powers the calculator, and the 7.3V charges the battery pack (which is 5 Ni-Cd cells, so nominally 6V). If this is correct it would do no harm to connect both of the pins to 6.6V.

Looking at the "jack" picture, there are three pins: 0V, +/-6.6V and +/-7.3V in some order. However, we still don't know what the polarity should be. Given that the calculator apparently uses PMOS technology, I wouldn't be surprised if the common pin was positive, not negative. Don't trust me on this!

A way around this is to open the case and get at the battery pack. Looking at the pictures of the interior (e.g., here), we see a red wire and black wire coming from the area on the right where the battery pack would be. Red is positive; black is negative, with close to 100% certainty. So open the case, remove the battery pack (probably not in great shape), clean things up, and connect your 6.6V supply to the battery pack terminals, with polarity according to wire colour.

(If your power supply allows it, limit current to 0.5A.)

Once you're inside you can use an ohmmeter to see whether any of the pins in the power supply socket are directly connected to plus (red battery pack wire) or minus (black wire). I would expect only one direct connection, and that would be the 0V pin. If it's connected to the red wire, connect the 0V pin to +6.6V and the other pins to 0V; if the direct connection is to the black wire, connect the 0V pin to 0V and the other pins to +6.6V.

Be really careful! If you don't want to open the case I would wait around in case some information on the adapter polarity turns up.

Nigel (UK)

Thank you for these very detailed instructions, Nigel!!! I appreciate them a lot and will definitely try it as soon as I have a DC power Supply