Presentation and question about calculators long term storage at low temperature

[Alevin]

Dear all.

This is my frist post. Let me introduce myself.

My name is Ricardo Aliod , mechanical engineering Professor at “Escuela Politécnica Superior de Huesca”, which belongs to Zaragoza University, in Spain.

I am committed to organize a “home made” small educative exhibition , about scientific pocket calculator history. Its under preparation at it is programmed to start next September.

I would like to post here two initial questions:


1) Frist one, related to exhibition. Mainly the items that will be exhibited come from donations (credited), but still we have a small budget for some acquisition of famous items like HP75B,(and other non HP calculators). If you could give us some help to find it apart form Ebay (since we have scrutinized there and we know what is offered ) at a reasonable price, please, send me a pm.

2) The second and main question is about calculators conservation and long term storage practices. Even as mechanical engineer I can understand that all Integrated Circuits will “naturally disintegrate themselves” as time pass-by and it will stop working for ever after a certain amount of years. So its an ephemera item, not a long lasting device.

What will be the expected half life of the 70´s 80´s vintage calculators in the best storage conditions?.

I made a search on the forum about the subject, andI founnd some topics – not many- and recommendations are simple (desiccated environment, constant fresh temperature,...).

As IC atoms self diffusion depends on temperature, what about the calculators storage at temperatures below 0 º C.(in dry atmosphere special refrigerator)?. Will it destroy other parts (capacitors, screens, weldings,…)?. Could it create cracks and breakdowns because of the different dilatation coefficient of different materials welding and assembling? Any experience or advise of your expert knowledge will be welcome.


R.A.

[emece67]

IMHO, such "atom self difussion" effects are really negligible (if not completely forgetable for the centuries to come) when confronted to external factors like:

• Moisture
• Radiation
• High temperatures and rapid temperature changes
• Improper handling (causing electrostatic discharge damage)
  

So, manage these 4 external factors and let your grand-grandsons enjoy the museum.

Regards.

[Maximilian Hohmann]

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

[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?

[Alevin]

(04-14-2017 06:10 PM)Gerald H Wrote:  

(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?

Thanks for your interesting contributions

A colleage told me about the electrolytic capacitors syndrome that ruined many talkies. LCD screens seems to be also sensitive whatever you do.

Very generous on your side for the offering to facilitate items for exhibition, But I think it will not be necessary by the moment. We are thinking in an periodic display, oriented not only for exhibition but also in preservation.

Some biologist fellow told us about storing in some kind of controlled atmosphere chamber they use. Someone suggested the idea of below 0ºC conservation, but I think it could apply only for nude IC.

Anyway, as early calculators will stop operating some day, we had the idea of filming their operation while they still are working (in some of them as in CASIO FX-10 is a fancy experience). Videos also should be preserved in the future, transfering from one format to other, ha,ha,... Some part of the recordings can be shown during the exhibition as people can´t touch the items.

[Alevin]

(04-14-2017 04:39 PM)emece67 Wrote:  IMHO, such "atom self difussion" effects are really negligible (if not completely forgetable for the centuries to come) when confronted to external factors like:

• Moisture
• Radiation
• High temperatures and rapid temperature changes
• Improper handling (causing electrostatic discharge damage)
  

So, manage these 4 external factors and let your grand-grandsons enjoy the museum.

Regards.

Indeed may be the most recent IC with a huge integration scale, using only a bunch of atoms to make a transistor gate could be more prone to fail in future, rather than old IC, where components were really “macroscopic”

Thank you for your clever advice.

[Giancarlo]

Hello,
As a conservation specialist in my daily job (for ancient artifacts) i use to store my calculators in almost sealed boxes with moisture absorbing materials like silica gel or others. Relative humidity and its variation over time is our enemy. With silica gels we are able to stabilize relative humidity. Normally (it depends on artifacts history) organic materials are well preserved with a rh around 50-55%
Metals need lower values of relative humidity like <40%. I am not a specialist in electronic components preservation value but i would assume that these components are impacted by oxidation supported by the presence of water vapor in the air.

Normally temperature is not important by itself, 99,999% of the artifacts are not subjected to temperature control. Temperature variations are dangerous because they are responsible of relative humidity variation so it has an indirect impact.

In modern artifacts what concerns me a lot is emissivity of materials like plastics or electronic components (the so called outgassing). For these materials there are some activated charcoals that could help to absorb these pollutants and replace them from time to time.

If someone is interested on this subject i may detail with other useful information like display cases air tightness and active devices to control relative humidity.

Thanks

Giancarlo

[Alevin]

(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.

Going back with the long term conservation issue, a doubt has arrised to me. Excuse my ignorance

If liquid electrolyte capacitors are present in early (and 80´s) calculators, and its dry out over time is a problem,... It could be that the silica gel used massivelly to combat humidty may acelerate the capacitor dry out?



Best regards

[Vtile]

I'm talking out of my league, but also long powerless periods will temporarily degrade atleast electrolytic capacitors. One of the corners of electronics which is constantly dealing with these are atleast antique radio collectors and I would assume the "volt nuts" that is the metrology equipment collectors and professionals.

[Alevin]

(05-11-2017 08:01 PM)Vtile Wrote:  I'm talking out of my league, but also long powerless periods will temporarily degrade atleast electrolytic capacitors. One of the corners of electronics which is constantly dealing with these are atleast antique radio collectors and I would assume the "volt nuts" that is the metrology equipment collectors and professionals.

Therefore, for calculators that are stored, a good procedure will be to periodically insert batteries or plug in AC adaptors and keep the stuff powered for a while?
Any suggestion of periodicity (once a month? Once a year?...) and switch on time (minutes, hours,…)?