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Mark · (This post was last modified: 05-29-2017 03:29 PM by Mark.)

Hello,
I'd like to seek advice from any Sanyo expert who may be around. I've put hands on a nice ICC-82D (2nd version) which is working. Its internal battery is dead, so I'd like to know if disconnecting it and running the machine on AC only would put the electronics at risk ?

Thanks to Katie Wasserman's site, I found the ICC-0081 schematics wiring. Both machines have many in common and even the first stage of the power supply is the same, but there's one exception : no AC/DC switch. (it totally isolates the battery from the electronics when in AC position)

I'll soon do some diagnostics on my machine because is seems that the transformer secondary (or the rectifier) dedicated to battery charging is dead. Anyway, any information is much welcome.

Thank you very much,
Marc

EDIT : argh, sorry ! I put it in the wrong category, should have been "Not remotely HP calculators". Is there a way to fix my mistake ?
EDIT 2 : many thanks to the administrators for having put my post at the right place :-)

Chasfield · 06-04-2017, 07:25 AM

Would it be safer to power the calculator from a good-quality, regulated 6v power supply, wired in so that it directly substituted the 5 cell NiCad pack?

Mark · (This post was last modified: 06-06-2017 06:05 PM by 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