Stuck Negative Sign in 34C Display

[vikram86]

Hi everyone! Thanks for the add, I'm new here, but have been following the site for awhile.

I just won a 34C, but the negative sign is stuck on. I have heard about loose connections causing segments of the LED to be blank, but never a segment stuck on.

The seller says that the self-test checked out perfectly.

I haven't gotten the calculator yet, so I'm not sure if it's an older one with the contact-build or a newer soldered model Spice.

Anyone know offhand what could be the problem? Thanks so much!

--Vikram

[Katie Wasserman]

(03-09-2015 03:56 AM)vikram86 Wrote:  Anyone know offhand what could be the problem? Thanks so much!

--Vikram

Welcome Vikram!

I've never come across such a problem on a Spice series calculator. However, the minus sign on the Spice machines is special in the sense that it's not treated like just a segment on a digit -- the main processor chip as well as the display driver chip have separate circuits to drive this segment. Most likely one of those has failed. If it's the display driver that has failed it might be possible to bypass this problem with a discrete transistor. If the problem is the output line form the main processor it's probably not going to be fixable without replacing that chip.

Maybe someone else here as seen this issue before and can offer a specific solution.

[Sanjeev Visvanatha]

Welcome!

I had considered bidding on that one, but after a bit of research, I Decided against it since I wasn't confident I could fix it with my amateur skils. I did find this post from a few years ago that documented a similar issue.

http://www.hpmuseum.org/cgi-sys/cgiwrap/...ead=216753

Good luck, and let us know what you find out!

[vikram86]

Thanks Katie and Sanjeev.

I will let you know once I get the machine how everything looks.

Luckily there's multiple guides online for these calculators...hopefully it's not too difficult a fix...