HP34C display partially lit



The bottom horizontal LED segments on my HP34C won't light up anywhere on the display...I put in a new custom-made battery pack & charged it overnight, no difference. The self-test didn't indicate any error & all the functions work fine. Any ideas what could be causing this, & some repair tips? Thanks in advance!


Hello Elizabeth, I recently repaired a HP32E with exactly the same symptoms. The problem with the 'spice'-series calcs is that the Display as well as the chips aren't soldered to the main- board. Sooner or later this leads to contact problems. A short repair instruction: 1. You need to unscrew the case. 2. Hold the case with the keys down (or they fall to the floor) 3. Snap apart the case (needs quite some force) 4. Label the chips on the main board. 5. Take away the metal clips wich run along the sides of the main board. 6. Clean all contacts on the main board 7. Put chips back on the right place (later models have the chips soldered). 8. Put the main board back toghether, fit metal clips 9. You may test the calc before completely closing the case, as opening the case again is a pain.

Hope this helps you Cheers Daniel

See also the following posts: http://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/forum.cgi?read=4266 http://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/forum.cgi?read=4302 http://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/forum.cgi?read=4304


Hi Daniel,

Thanks for your advice...After getting the case apart, I cleaned all the contacts with IPrOH; some of them were very dirty. Unfortunately when I put it back together, the 34C didn't turn on at all...turns out that the two thin metal strips on the battery cable had badly corroded, and snapped. The large metal strip is still intact, as is the cable itself. Is there any way to fix these that you know of?

Thanks again for your help...much appreciated! Elizabeth


Hi Elizabeth,

I'm not sure which metal strips you exactly mean. But i found this earlier post: http://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/forum.cgi?read=4254 You possibly have to replace the supply cable with ordinary leads. I'm sure you get it working again :)

Cheers Daniel


Hi Daniel...I was talking about the metal strips inside the supply cable. I'll give the ordinary leads a try...thanks again! Elizabeth

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