Presentation and question about calculators long term storage at low temperature

[Gerald H]

(04-14-2017 04:54 PM)Maximilian Hohmann Wrote:  Hello and welcome!

From what I understand, the main problem is not so much the integrated circuits, but electrolytic capacitors which dry out over time, no matter what the storage conditions are. Many old calculators rely on them for the voltage boosting circuits required to drive the displays, either LED, VFD or Panaplex.

I have been collecting calculators for quite some time and bought them from very different sources, often with absolutely no knowledge (or control) of their storage conditions. Sometimes corrosion or boxes and instructions stained from moisture tell a story about non-ideal conditions. But in my experience (apart from obvious corrosion in switches and battery contacts) it is rather the manufacturer who determines the life expectancy and not so much the user/owner.

There are brands which produced calculators that almost always work (like Compucorp/Monroe and Aristo (Dennert&Pape) of which I have never seen a non-working specimen, no matter of the state of conservation) and others which after 20+ years almost never work (i.e. "Santron", "Unico" and similar late-70ies cheap stuff). Hp is so-and-so in that respect. I have never seen a non-functional Hp-35 or 45, even if it looks as if it was stored in some mudhole, but of the 20- and 30- series only every second one still works in 2017.

In case you need specific exhibits, just post a list here. If I have something, I will happily borrow it for your exhibition.

Regards
Max

Don't all the capacitors in HP calculators, even the 35, use solid electrolytes?