HP 15c Collector's Edition save/restore does not work

[Johnh]

(09-28-2024 12:31 PM)AnnoyedOne Wrote:  Yes. The batteries are supposedly in parallel. Do you have a multimeter (on ohms, no batteries) that can be used to verify this? Could be a simple connection issue.

Thanks for replying, I did the multimeter tests, batteries removed. From the side contacts that connect to the exposed upper '+' battery faces, there is a direct zero-Ohms connection.
But there is no measurable connection at all between the two 'spider' '-ve' contacts under the batteries. this is at any Ohms range from 200 to 2M, with meter leads either way around.

Curious! the first time Id every opened the battery compartment after a year of use was yesterday. If its intended as a simple fully-parallel connection between two batteries, then it isn't that in my case. But it occurs to me that sometimes when two batteries are sharing a load in parallel, it is good practice to feed each of them through a forwards diode, to block direct current flow from one battery to another in the case that one has more charge. That would come with a small loss of voltage to the circuit, but would have suppressed my meter test?

Does anyone else notice a similar issue with an HP15C CE? ie, can you remove either battery when switched off, and then replace it and your data is still there when you switch on? or as on mine, does it reset as soon as you remove the more central battery?

I'm just out or warranty with this machine, which I bought from Calculator World in Australia. (If I had to do a work-around fix myself, I think I could solder a fine insulated wire between the '-ve' contacts, fed up and over via the recesses used to lift the batteries, without opening up the back. A last resort though....)

VoyagerSave

(09-28-2024 12:31 PM)AnnoyedOne Wrote:  Good. Its not rocket science.

I agree, its Computer Science!

Making these cable connections and updates is different to achieving similar on other consumer devices, such as phones or audio interfaces etc. Sam-ba and the use of the command prompt is not familiar territory for most of us these days. Im happy to work through it, and Im really happy that we have these features. But from this and other threads, some have encountered difficulties, and sharing experiences here can help.


John