HP Forums

Hello,

I am new to the forum and a complete beginner. I own a 12C which I purchased back in 2014. I used it for about a year then it went into my top drawer in its leather case, not to be used until recently. When I turned it on, the display hardly showed any numbers, but it was attempting to show me some. I changed the batteries to ones from a pack that I had in a drawer, but that yielded the same results.
Upon a serial number check this calculator was made in China in 2012, which doesn't seem that old compared to what I'm reading about the history of this calculator.
I tired the reset button located near the battery compartment, no change. I tried the (-) sign reset no change. I tried the paper clip to connect the + and -, and drain the capacitor, no channge. Before I purchase another 12C, I was hoping there was a way to fix this.
I did read that someone warmed up the screen connections from the inside, but I have no idea on how to open this up properly.
Any help would be appreciated.

Before you do anything else, I suggest you try it with new, good-quality CR2032 batteries; from your description, it sounds like the batteries may have been sitting around a while. When batteries are low, behavior of these machines is odd and nor easily predicted or consistent.

Remove both old batteries, short the terminals in the bay, press [ON] to bleed any residual charge in the board and let it sit empty until you get the new 2032 cells (but at least overnight).

Let us know how it goes.

Hello!

And a (perhaps) stupid question from me: Did you try to increase the display contrast? The newer 12Cs, to my knowledge all models that are powered by CR2032 cells, have that function: press "f" together with "+" or "-" to change the contrast.

Regards
Max

Welcome to the forum!

I'm afraid this condition seems to be a common affliction of the earlier releases of the new 12C with 2 CR2032 (S/N beginning with CNA; 4CY; and others).

It appears to be (in my humble opinion) a systemic flaw...

P.S. You can implement your mentioned heating method, without opening the unit, by simply placing the unit in the sunlight for some time, but it remains a very temporary fix at best...